First, let me say that I’m cursed by the fact that so far I’ve blogged everything I’ve done with my RepRap, and I don’t want to stop now. I’m currently behind by about 9-10 months! My last post was in May of 2011 – today is October 2, 2011. (This feels like debt!) What makes it worse is there’s a whole bunch of pain in those months, but I pride myself on posting my failures as well as my successes, so I’ll post it all – but know that I’m not doing as bad now as these posts are going to show!

Ok.. So.. Back at the end of January 2011, my birthday gift arrived – a metal lathe! Yes, I know that today there are so many people with RepRaps that everyone just buys pre-made hot ends and never experiments anymore, but screw that – I wanted a lathe. I was so sick of trying workarounds that involved doing strange things with my drill press, which were in fact clearly lathe tasks.

So, it arrived:

As you can see it was covered with packing grease, which happened to be a deep crimson red, which felt at least a little unsettling, this being a powerful lathe and all…

After a whole lot of cleaning off of grease, Alicia stood guard over my first test run:

Next I practiced using the lathe with some machinable wax, and made my first thing with the lathe:

And here are two more pictures just for the hell of it, the 2nd one 3D (cross your eyes to get the images to line up):

I then left the lathe for a while to make a heater block for my extruder (so I’d no longer ever have to wrap nichrome wire again).

Then I tapped the hole to M6. Adrian’s original extruder nozzle was threaded (and thus the heater block was threaded too). A later heater block of his (which I eventually make months later) is smooth instead, using just an interference fit. This particular heater block I ended up using on my old M6 heater barrel. Here’s what the tapping looks like for those unfamiliar with it.

Then it was time to assemble it. A large resistor goes through the large untapped hole, and the end of the thermistor goes in the smaller hole.

The resistor needed to be cemented into the heater block, which required me to open the fire cement that I’d bought a year earlier for one of the earliest designs of extruder that I thought I’d make.

I took out the thermistor, packed up the resister hole with some of the cement, put it in the oven at 200°C (around 392°F) for like 15 minutes, and here was the result.

Here’s a picture of it screwed onto my old-style heater barrel (which I’d made on the drill press, but which still works today):

…and then here’s the whole thing in my Wade’s extruder, with the thermistor back in, all wired up with crimped bootlace ferrules, and wrapped in kapton tape:

Now it was time to test it! I hooked it all up, got very excited at the prospect of never having to rewrap a heater barrel with nichrome wire again, and tried heating up the heater barrel. And? And.. nothing. It wouldn’t heat at all. I was trying to bring it to 200°C but it stayed around 16-17°C:

So I double checked everything and eventually found……. ….that I had accidentally ordered the wrong resistors! AAGGHH!! I had accidentally ordered 6.8Kohms resistors instead of 6.8 ohms resistors. I’d have to order new resistors and redo the entire heater block, fire cement and all. Grrrrrr…

Ok, so I ordered the resistors, then the next day – back to lathe work.

Ok, so the main reason I wanted a metal lathe was to be able to make heater barrels better than the ones I’d been making. To drill a 0.5mm hole in the end of the barrel, I’d need to be able to hold onto one of these tiny 0.5mm drill bits somehow in the tailstock of my lathe (so it can be slowly pressed into the spinning barrel, cutting the hole). Before my lathe I’d been able to hold the 0.5mm drill bits in a vise in my drill press but now it had to be held somehow in the tailstock. The thing is, the chuck in my tailstock was way, way too big to hold those drill bits.

I’d wanted to make a heater barrel that day (a Saturday). The smallest thing I could typically find in stores around me were Dremel drill bits (and the collets that hold them) that were way too big (1/32″, around 0.8mm). But then I saw this Dremel 3-jaw chuck online.. It said it only went down to 1/32″ as well, but then I found a European ad for the same product that said it would hold something as small as 0.4mm, which had me believe it would work fine. Here’s what the 3-jaw chuck looked like:

I called a bunch of hardware stores around me and found one that had it in stock. I drove over, wanting to do all of this that day, bought it, and returned home. I figured that I’d hold THIS 3-jaw chuck in the large chuck in the tailstock of my lathe, and that’d be that. But it turned out not to be so easy.

I’m going to show the result video first, because I think it makes a better presentation that way. Watch this video:

Man that made me happy. Yes, I know there are other ways to hold small drill bits (and in fact just this week I finally placed an order for a mini pin vise that can hold a #80 drill bit (0.0135″, or 0.343 mm)), but the cool part was that I had a want to do that THAT day, and I was able to, by making that part with my lathe (including learning to cut threads, which was really cool).

Here’s how I built that.

First, I knew I had to cut threads with the lathe (my tap&die kit is metric, and probably wouldn’t cut threads that small anyway). I determined what the threading was on my Dremel shaft by inspection first, then I confirmed it by Googling it and finding out that it was 40 threads per inch. So the first thing I had to do was open up the panel on the left hand side of my lathe and change some gears to make the leadscrew turn at the correct rate to cut 40 threads per inch. Here’s what the original gear configuration looked like before I changed it:

(That’s a 20 toothed gear for A, 80 toothed gear for B, 20 toothed gear for C, and an 80 toothed gear for D).

I followed the lathe manual’s instructions on changing up the gears for 40 threads per inch, which involved removing one of the gears and changing some.

Then I put a piece of aluminum rod in and turned it down to the correct diameter. I marked where the threads needed to go with black marker.

I put in the right cutting tool for cutting threads and lined it up perpendicular to the piece. I started cutting the threads, one pass at a time, and frequently went back to check whether a normal Dremel cover (which has no center axle) would screw on or not yet.

Thread cutting is pretty fun – it’s an interesting experience. I wanted to document it and show exactly what steps I go through to do it, so here’s a pretty detailed video showing a few passes of cutting threads and what I do to cut them. I like this next video:

Then after a while I ran into a problem where it seems the diameter of the cut threads was actually larger than it was before cutting, as if the metal was swelling or something (maybe it’s because it’s aluminum?). I’m all ears if any experienced lathe operators want to explain this:

Well I think what I did after that was actually file down the threads a bit, and eventually, I got it just right:

That allowed a standard Dremel cover to be screwed on, but since it wasn’t a hollow shaft yet, the Dremel chuck couldn’t screw on (because if its inner axle). So here I used a center drill to start the hole that I’d ultimately cut with regular drill bits:

And then, success!

Here I’ll quickly mention one non-RepRap thing that I did with my lathe right after that. The handle on my toilet broke, leaving it looking like this:

Well I decided I didn’t need it to be pretty, but I wanted to figure out a way to fit those two back together. I didn’t even need to thread one side and tap the other – it’d be fine if I just had a section of smooth rod that I could hammer into a slightly smaller hole on the base for an interference fit. It was, of course, just an excuse to cut something else on my lathe.

Fixed!

One week passed, and the new (correct) resistors that I ordered for my heater block came in. The first thing I had to was drill out the old resistor that I’d cemented in the block.

Then, while I was downstairs, I made a perfect PTFE insulator on my lathe (feel free to go back and compare it to the off-center horrible insulators I’d made in the past on my drill press):

I then drilled holes for mounting it in Wade’s extruder with the jig that I’d made previously:

It was at this point that I made the CRITICALLY WRONG HORRIBLE MISTAKE OF NOT USING THIS PTFE INSULATOR! I got lazy, and decided I’d use the previous one, since it still seemed to have pretty good tension when I screwed it in. (Jeff contains his anger as he types this). This turned out to be a monumental mistake that cost me dearly.. but you won’t read about that until my next blog post.

Not realizing the mistake I was making (the affects of which I wouldn’t feel for another whole day), I hooked up everything again (the heater block with the new resistor, but mounted in my OLD PTFE insulator), and tried testing the heater block.

The next day, I hooked it up, and did my first print with my new heater block.

And I’ll leave you with one peaceful, uneventful video I took of it printing that afternoon, and end this post on that happy note. My printer was printing nicely, everything was going well. What a beautiful machine.

Stay tuned for part 4 of ?

First I tried printing the small gear for Wade’s extruder. I tried with an infill width of 0.6, which was too close together (should have stuck with 0.7).

Here’s more video of it printing (no narration):

And here’s video comparing the result to previous failed attempts:

The result:

Given the globs of PLA inside that previous gear, I thought that maybe one of the issues was that the previous layers weren’t cooling in time, resulting in a messy goopy print. So instead I tried printing all of Bed 3 of the Mendel RepRap (an entire bed of parts), so that each layer was separated from its previous layer by a huge chunk of time.

My first attempt failed – it ALMOST completed the first layer, then jammed the head into the bed, resulting in a video I won’t include here because of the anger it contains. Here are pictures after the head crash (which was causing the heater barrel to be dragged from side to side):

A week later, I used my new chop saw to cut a new piece of PTFE:

I then had a worse attempt at printing Bed 3:

To the basement! I went downstairs to make (another? can’t remember) PTFE insulator, and hob a new bolt (with the hobbing jig I’d printed previously, which I showed a few posts ago).

Here was a wood jig I made to cut the center hole in the PTFE, and the two side holes to mount it in Wade’s extruder (which I’ve now used successfully multiple times):

Next I wanted to hob another bolt. Last time I’d done this, I held two bearings together between two pieces of wood clamped in a vice, which wasn’t the most ideal solution. This time I used the Pinchwheel Worm Drill Jigs that I posted about previously.

Then I assembled the extruder. Here you can see the newly hobbed bolt in place:

Next, I tried printing a bed of parts again.

At this point I started to get pretty hopeful.. The shapes were the right proportion/size, I’d made it past the initial layers, and everything seemed to be going well..

So I went upstairs to go to sleep, and allow my RepRap to continue printing its own spare parts into the night. Of course I brought my iPhone with me, and occasionally woke up just enough to take a peak at my iPhone to see my webcam feed of the RepRap to see how it was going. I saw these:

Fail! It was fine in the first two of those pics (at night), but the last two show a mess.

The reason? The reason was this:

Aaaaggggh!

The pictures taken at night showed everything going well, so the problem only occurred after the knot held the spool from turning, and plastic must have poured all over the place..

Since then I’ve found myself pretty paranoid about the filament spindle and whether it has enough slack in it, and I check on prints every 15 minutes or so to make sure they’re not having problems. PLA is pretty strong, so a knot isn’t pretty.

Anyway, two days later, I tried printing again, and managed to print this entirely usable alternate X-axis motor bracket, which takes the X-axis belt on a far less torturous path than the old one. (I still haven’t used this piece)

At some point I tried printing out this gear for the Z-axis, which didn’t come out too great:

It was around this point where I started trying to print parts for Adrian’s Geared Extruder. With the temperature problems I was having I didn’t have the best quality prints, but at least they were close:

And then this piece..

Here was a picture of a bunch of the PLA pieces I’d recently printed, all arranged together:

Finally, I tried printing the big gear for Adrian’s Geared Extruder:

Here’s another arrangement of pieces (this time just for Adrian’s Extruder).

And finally, here are two close-up pictures of that gear. The temperature problems created this possibly usable, but certainly strange looking, gear. It’s more interesting to look at than to use at this point:

Well even though this is a pretty short post compared to most of mine, I feel like this is a good point to stop. Coming up in part 3 – my metal lathe arrives! (remember, I’m still catching you all up on things from around January/February).

Stuff From Before My MiniMug Post

For my January 3rd post I jumped ahead and immediately posted the pic of me celebrating my minimug. I still have stuff from before then to post.. Here’s the best I can do from memory and piecing it all together from pictures (as always, there are a lot).

First of all, I’d fixed my X-axis problem as I said two posts ago, but little did I know that I had a subtle Y-axis problem too (that I just hadn’t noticed, because of my large X-axis problem). But I hadn’t figured that out yet. All I knew was that my horrible X-axis problem was solved, and parts looked way better.

So, I printed some parts (which, again, still weren’t perfect, but I didn’t fully realize that yet).

A calibration piece (lit by a flashlight I loosely attached to the frame):

There’s a subtle y-axis problem with that print (which I’ll get to below), but I wasn’t focused on that problem yet – I considered this print a success.
Encouraged by that relative success, I decided to try printing better quality versions of the filament spindle that I’d created before.

Compare that to this previous print from two posts ago, before I’d fixed my X-axis:

Here was video of it printing:

Then on December 30th the kids were playing one of the versions of PacMan we have on the xbox 360. I had an idea, pulled out my laptop, quickly designed a PacMan model in OpenSCAD, and started printing six of them (one for each of us).

I gave them to Laurie and the kids, all of whom loved them, and asked if they wanted to see how I designed it. (At the time Emily was 7, Alicia 5, Cara 3, and David 1). They said yes and I showed them how we could make a cylinder, how we could extrude a triangle, how we could add those two with a union, and how we could subtract those with a difference. They immediately asked if we could design the ghosts.

(For later ghost prints I made the “eye” part an optional OpenSCAD parameter, because it didn’t look as good with the pupil in it).

Next, I wanted to fix the subtle Y-axis problem I was having. My Y-axis was still using the old McMaster pulleys from before, and although it hadn’t caused any huge noticeable problems like my X-axis had, it did cause problems. The calibration piece at the top of this post shows it best – the infill of the object was crossing over the perimeter that had been drawn – I was accumulating Y-error. The fix involved removing my bed, so that I could loosen the belt, so that I could remove the Y-axis motor, so that I could get off the pulley, and replace it.

I replaced it with a printed pulley, put it all back together, and tried printing another calibration piece. Even though I had to abort the piece mid-print (because a loose connection caused the thermistor input to glitch, causing the temperature to drop and the plastic to stop flowing), the results before I aborted showed that I had indeed fixed my Y-axis problem. Pay particular attention to the front of the right-most part of the piece, and see how it’s smooth instead of bumpy.

Y-axis problem solved! X and Y now print beautifully!

That confidence led me to go back to trying to print a minimug again, which I did (and blogged about out of turn last time).

Even though I had these great smooth perimeters in the calibration piece above, that wasn’t what was needed for me to get an alcohol-tight minimug. I’d determined previously that in order for it to be alcohol-tight, I needed to cram plastic together. I changed the ExtrusionInfillWidth from 0.7mm to 0.5mm, and plastic globbed everywhere, making a nice alcohol-tight minimug (which looked much more bumpy on the outside).

Here was the first of the recent attempts, which was close but not even water-tight:

…but, as you can see…

The next one started out much better, and had a promising base.

It seemed water tight at first:

but then it leaked:

That made me try an infill width of 0.3mm, which was WAY too small. Here’s a horrible video of the extruder just plowing through plastic (not a good idea – don’t try this at home):

I aborted that one (in the foreground of the next pic), then started printing what would be my first alcohol-tight minimug (the star of my last post from January) in the background on the bed:

The successful minimug (0.5mm infill width) was born. If you missed it, you can see that post here, with its pictures and video.

Now you’re caught up on everything that happened before the last post. And this seems like a good place to end this one. Coming up next, more of what’s happened since January – I start trying to print parts, my new lathe arrives (!), etc. Woohoo!

Here’s video of my official toast!

More pics:

Here’s what it looked like before putting any alcohol in it:

The alcohol is Rīgas Melnais Balzams (english: Riga Black Balsam). My mother was born in Riga, Latvia, and in 1999 we (my parents, my brother, and I) backpacked through Europe to get to Latvia. I’ve had that Balzams sitting around for a long time waiting for an occasion – this was it!

And this minimug was no fickle just-barely-works-once-well-enough-for-a-photo piece – no! We went out for dinner tonight and I brought it with me, and filled it again! Here is is filled with Merlot:

I’d had many water-tight minimugs before this, but none of them alcohol-tight. Then for a long while I put the goal of trying to get an alcohol-tight minimug on hold until I’d made it further with calibrating my machine. After recent successes, I tried printing a MiniMug again, and a few prints later, I had it.

I’d say the main differences between now and previous attempts were:

• My X and Y axes used printed 8-toothed pulleys instead of the 10-toothed McMaster pulleys I was using before. (The 3rd generation boards I have only do half-stepping, not the 16-step microstepping that newer boards can do – and without that I wasn’t able to get great resolution with the 10-toothed pulleys)
• The filament spindle I made prevents drag on the X carriage, which was severely hurting my prints
• A geared extruder (in my case, Wade’s Extruder) with a strong stepper was necessary to get a constant, reliable flow of plastic

This minimug (“try39″) was printed with Ultimachine 4042 PLA, printed at 200ºC, using the RepRap Host software. The firmware is from the 20101211 debian package. The RepRap Host preferences were mostly the same as the standard preferences with the following key exceptions:

• For the minimug, I changed the infill profile to be the same profile as the perimiter (“PLA”) since I wanted a ton of plastic
• After trying just the above change and still having the bottom leak, I tried changing “Extruder0_ExtrusionInfillWidth(mm)” from its previous value (0.7) to something real tight – 0.3. That was waaaaaay too close – a TON of plastic printed out, and the extruder head was basically swimming in plastic and it wasn’t going well. I aborted that one, split the difference, and tried 0.5, which made try39.

The sides are very thick, the minimug feels far more sturdy and solid than the others did, and it feels a bit heavier. I used to try printing with the number of shells set to 2 – I think that was a mistake.. Here I went with the default (1) and it still did an outer and inner wall, and filled in the solid part of the wall.. Perhaps the extra shells left no room for infill before.

The outside looks all bumpy because I had “Extruder0_ExtrusionInfillWidth(mm)” set so tight that plastic was bunching up everywhere, which is what I wanted. I wanted a molten pile of plastic holding in alcohol – not a fine mesh air filter like I was making before. I won’t be using that set of RepRap properties for everything – that’s for sure. I do think that if I spent more time tweaking the value I could probably get a smooth-outer-edge minimug that was still as solid and alcohol-tight, but that seems less rewarding than printing out a set of spare parts.

So – WOOHOOOOO!!!!! IT’S DONE!!! I did my toast. That was a long wait. Now my buddies can’t use that “but it can’t even print an alcohol-tight minimug….” joke anymore.

I’d done other things before this minimug, which I’ll blog about later – I wanted to get this out first.

Printing again

One shipment of gears later, and I’m printing again.

I took the opportunity to do a few things, each of which had benefits and consequences:

1) I finally corrected my mistake and set up the bolts in Wade’s Extruder correctly. (I bought 4 M4 bolts with hex heads (70mm long I think) at Lowes – it was nice being able to go to a local hardware store and find metric anything.. There’s nothing metric at Home Depot that I’ve seen (at least not near my house). That did make it much easier to mount (no worrying about trapped nuts falling out, because there are no trapped nuts – those holes are for hex bolt heads).

Ok, that one didn’t have many consequences. I’d just been putting it off.

2) I mounted my Wade’s Extruder sideways with Tony Buser’s sideways mount piece.

When I ordered some gears from Tony, I also ordered a print of his sideways mount for Wade’s extruder. I’d expected this but he sent me two versions; the version I used was this:

I’m not sure exactly where this particular object is on thingiverse, if it is at all. It looks a lot like this part of thing:4307 but it’s different enough that that’s not it. I haven’t gotten around to asking Tony where the model is for this. Hey Tony, upload this version, it works great!

The immediate benefit is more build height. When printing the bag holder that I use to take the trash out to the curb, I wasn’t able to print all of it because my extruder’s stepper motor would hit the top of the frame. With Wade’s Extruder rotated 90 degrees, the X axis can raise much higher.

The new build on the left was able to print to its full height.

The second huge benefit is now you can mount and unmount Wade’s extruder without having to disassemble the whole thing. The idler bracket can stay exactly where it is.

The third benefit was that the heater barrel is now centered in my X carriage. This had been a concern for me before, as it was previously off-center, with the heater barrel right up against my easily-meltable PLA x-carriage.

And the fourth benefit is that the bolt hole in front of the large gear has a recessed area for the head of the bolt, so it’s well out of the way of the large gear. Previously, taking the large gear off of Wade’s Extruder meant straining everything to bend back the extruder to pull the gear out. Now, it comes right out.

Ok, but issues arose. First, to get my PTFE insulator through the hole, I had to remove it from my Wade’s extruder (because of the wires for the heater and thermistor). Then, some of the kapton tape fell off (I’m looking forward to someday leaving kapton tape behind), and the thermistor floated free in the air instead of being held against the nozzle. I agree with what I read someone say a week or so ago – kapton tape is not a real solution for holding thermistors against barrels. (or maybe my roll of kapton tape is just getting old – it doesn’t seem to stick like it used to).

So I had to at least slightly rewrap. But I had to do that anyway, for a different reason. Tony’s mount is at least 6-7mm tall if I remember, and with the short heater barrel I was using, that made my heater barrel not go down as far as the bolts on the bottom of my X axis.

It also meant that the inside of my X carrriage was exposed to more heater barrel. That’s one of the reasons I wanted to rotate the extruder in the first place – concern for heat in my x carriage.

I dreaded having to make another (longer) heater barrel right now. I just made one recently, and it was the one I made on my own without any external nozzle (the original Mendel heater barrel design). Plus, I’ve wanted to keep the heat zone on my heater barrel very short, so I don’t use longer purchasable heater barrels (even though I have some lying around). Plus, that wouldn’t solve the heat-in-my-x-carriage issue.

So instead I realized the solution was to make a longer PTFE insulator. That would lower the heater barrel, and insulate the carriage from heat. I’ve made several, but they’ve all been a pain. This is another area where a lathe would be nice. I couldn’t do my spin-the-piece-in-my-drill-press trick because the 16mm PTFE was too wide for the chuck of my drill press (I did wonder if people sell some sort of chuck extender to fit into an existing chuck and provide a much wider one.. but then I realized they probably don’t, because really that’s all the stuff of lathes). So instead I just drilled it, it wasn’t centered perfectly, but it worked. I decided to make it 13 mm longer, so I made it 48mm long. 3mm hole all the way through, then I think I used a 5mm bit on the other side (15 mm deep) before tapping it M6.

The next issue I ran into (that might have been a problem I already had?) was that with 3 washers, the large gear had at least one time on its full rotation where it’d push up against the small gear too close and catch/hang. Spacing it out with an extra washer fixed that, but moved the knurled part of the screw even further away from center (but again, it extrudes and prints, so..)

Battling with my X-axis: Part 1 (The Problem)

So now that I was printing again, and that I’d tested printing that taller bag handle above, I printed a test “K” block. Despite my attempts to ignore my x-axis problem for the short term, this was un-ignorable. Look how horribly all-over-the-place this block is in along the X-axis (left to right):

The Y axis is fine – looking at that from the side shows the edges line up. But looking at that from the front, you can see that layers go left and right from where they should be. As it turns out, this was caused by one of two overlapping problems I had with the X-axis – but I didn’t know this yet.

I had several theories about what might be wrong with my X-axis. One theory – the one that I started working on first, was that there might be some drag on the X-axis from the filament supply I had resting horizontally on a lazy susan behind the RepRap.

I’d used this lazy susan with the Makerbot successfully before, but I think the reason it worked in that case was because the Makerbot’s extruder doesn’t move – it just stays in the same location. As a result, the only issue for the Makerbot was whether it grabbed enough plastic. On Mendel, however, the carriage moves left and right, so extra drag on the filament might cause problems with the carriage moving. Plus, there’s a horrible coiling affect that happens when plastic comes off of the top of the spool, converting from its horizontal resting position to a vertical pull into the extruder:

Battling with my X-axis: Part 2 (Attempt to Test a Theory)

Upon describing this to my Dad during a long drive to a football game (Go Pats!), he asked if there was a way to remove the extruder and instead mount something that could hold a pen. That way, the filament-drag idea could be tested, by removing filament from the equation.

I immediately replied that yes there was, and that I’d planned to download and print a pen holder one day, but probably after I had everything working. Still, I figured it was worth a try. So I downloaded the Mendel Pen Holder, put the parts in an RFO file, and tried printing all three parts at once. (That was a knowingly foolish move, but it turns out to have yielded a good example of my X-axis problems.

It didn’t turn out well. Here you can see the three parts. Because I forgot to set the print order of the parts correctly, the back part printed first, then the part on the right, then finally the part on the left. As you can see in these pictures, my X-axis was accumulating error as it progressed within each layer, such that the third object printed was in a far different location than where it should be.

Specifically, look at the tall portion of the third part printed (on the left). It seems shifted way to the left of the base of the piece. What’s actually happening is that the base was shifted way to the right of where it should be (because of all of the error accumulated during the lower layers, from printing out the other pieces). The carriage was drifting more and more to the right of where it should be. But once the Z-axis had raised enough that the other two parts were complete, you see the higher portions of that piece were now printing where they were supposed to be (but since the parts below it were to the right, the top appears to drag left).

This was actually an illustration of my second overlapping problem with the X-axis, but again, I didn’t really know for sure yet that there were two problems.

I believe I made one more attempt to print that tall piece on its own, but I then put on hold the pen mount until later, instead deciding I’d just plow ahead with one of the solutions I’d already planned. (McMaster parts arriving in the mail helped that decision along, as you’ll see).

Battling with my X-axis: Part 3 (The Filament Spool/Spindle)

I’d determined that even if it wasn’t the cause of my X-axis problems, I wanted to build a vertically mounted filament spindle (or filament spool – both terms are out there), to reduce any drag whatsoever on the X-axis.

I looked at the existing spools on thingiverse and finally settled on a combination of three things:

1) Simple spool system for a Mendel (or other 3d printer) by camiel
I didn’t actually print any parts from this entry – I just followed instructions on it.
2) Simple spool system for a Mendel (or other 3d printer) by brokentoaster
This was a modified spool bearing, where you put the 608 bearings in the spinning part itself. I also studied the pictures in that thing to figure out how I wanted to mount it, including printing out 8 y-bar-clamp_10off pieces and buying the appropriate bars/nuts/bolts/etc.
3) Extensions for simple spool system for a Mendel (or other 3d printer) by Gavilan
These extensions bolt onto the 3 support bars, to keep the filament from spilling over the left or right side of the spool.

What I ended up with was uuuuuuuggggggggggggggggggggglllllllllyyyyyyyyyyyyyyyyyyyy, but it worked, and solved one of my X-axis problems.

(And actually those above weren’t that bad.. what was ugly, was to come). I realized that my X-axis problems would affect this piece, but I figured I’d print it, and if it was even SLIGHTLY usable I’d make it work (however I needed to), and if it solved my X-axis problems, I could print a better quality one later). Here’s the ugly:

This picture actually makes me feel dizzy looking at it, like I’m seeing double, but I’m not:

More ugly:

And if you don’t feel drunk yet, three more:

Then I printed out the extensions.

In this one, you can see the drastic difference that having the Z-axis optoendstop correct has; the piece on the left had the nozzle home just a paper’s thickness over the bed – the others were printed previously, when the endflag was too low (causing the nozzle to start too high).

Undeterred by the fact that there was no way a 608 bearing would smoothly fit into that, I bought a nice set of forstner bits and drilled out an appropriately sized hole. I put in the bearings, used a hot glue gun to make it fit nice (and fill in some of the holes in the plastic), and eventually ended up with this:

Then I put filament on it, and mounted the extension pieces.

And then, I mounted it on my Mendel!

Brace yourself: extremely exciting video ahead:

Then I tried printing another K block. Here was the glorious result of that print (ignore the brown spots):

Note the smooth lined-up edge on the left

The filament spindle had indeed fixed the first of my two overlapping problems with the X-axis.

Did you hear my foolish optimism thinking that that might have solved everything?

Ok so once I came down off that high (double rainbow, all the way!), I cautiously tried printing what had failed spectacularly for me before – a large Wade’s Extruder gear. In this next picture, the new print is on the bottom left, the previous attempt from the summer is above it, and an ABS gear printed by someone else (not sure if that was the one from Neil that broke or a new one from Tony) is on the right.

I’d actually let myself think that maybe the filament drag (fixed by the spool) just miiiight have actually been the entire problem. Nope. So this was the first time that I definitively knew that I’d had (at least) two different overlapping problems with the X-axis, and that I’d only solved one of them.

Battling with my X-axis: Part 4 (The Belt and Pulley)

So I moved onto other theories that I’d had. The belt could be too loose, maybe I hadn’t filed the shaft down on the X-axis stepper and the pulley was slipping, and here was a big one – maybe the McMaster pulley (a 10-toothed pulley) required microstepping to get adequate resolution (vs the 8-toothed printed pulley that’s supposed to be standard).

Worse theories hovered in the air like a storm cloud – maybe my X-axis bars were corroded/dirty enough that they were causing problems, or perhaps the plastic had shifted and now the X-axis bars weren’t parallel. Maybe the bearings in my X-carriage were gunked up, and it was just broken. Replacing the X-axis would be a major pain in the ass – I’d have to take off the Z belt, I think I’d have to take off the bed, etc. No fun.

Here’s a video from earlier when I was printing that pen mount.. Once I saw that it was making mistakes with layers, I filmed about a minute or so of the underside of the X-motor-bracket, where the pulley goes through this torturous path around bearings and the pulley. Note that the pulley was the McMaster pulley I purchased last April, which again has 10 teeth:

The belt certainly looked suspicious.. Maybe loose. Just barely hanging on to those turns. Plus, again, there’s the potential resolution problem that a larger pulley could be contributing.. One full turn moves 10 teeth instead of 8, and the number of steps for the motor stays constant, so there’s at least some less precision with this pulley than with a printed one I have lying around waiting to be installed.

So I decided to start down the road of replacing that, and that meant removing the X-belt from my Mendel. That was something I’d wanted to avoid if possible, since it meant changing a key variable in the equation (the tension of that belt), and who knew how much worse that might make things. Worse, if I removed the belt and the carriage still didn’t move smoothly, several of those worst-case scenarios might suddenly emerge as likely.

I dove in and removed the X-belt.

Beautiful. Very smooth. So that left the pulley, motor, and belt tension.

I removed the X stepper motor and took off the McMaster pulley. Sure enough, I’d been lazy and hadn’t filed down the stepper motor, but if I remember correctly I think the set screw had dug in pretty firmly even on the round shaft. So the first thing I did is file the shaft. When I was filing, I wasn’t sure which way nophead’s pulley (sent to me by Neil Underwood with my Wade’s Extruder) needed to go on, so I filed two parts (rather than filing the whole thing).

It turns out, it needs to go with the fat part on the outside:

You can see why here:

I put the pulley on, and tightened the belt much tighter than it had been (but still not so tight that nothing moved).

I recompiled the firmware to change X_STEPS_PER_MM to be the default setting for the 8-toothed pulley, uploaded it, and printed a calibration object. It came out beautiful.

That was good to make sure I had the new settings right for the new pulley, but it didn’t test the real problem. The best test for that would be the Wade’s Extruder gear, since that had always failed spectacularly.

So I printed that.

So good! It might be just a tad shy of usable because it might be slightly oval (because I still can tighten up the calibration from the last calibration object I printed), but that might be just being overly cautious. But anyway, that’s not the point. The point is – that solved my second overlapping X-axis problem!!!

Need more pictures of the successful gear.. Here it is compared to the most recent failure:

And here it is next to the functional one made out of ABS. Again, the color/transparency issue is because the gear I printed was printed with PLA (which is clear), vs ABS which is opaque and beige colored.

Horray! So I then remembered that I’d wanted to print out two Pinchwheel Worm Drill Jigs in case I needed them in the future – so with my new functioning printer I printed two out:

They came out great. Then even though my X-axis problem was solved, I went to address one of the last items on my list – I figured I’d at least try printing an alternate X-motor bracket that eases the path for the X-belt. I started a build, and headed up for bed. Luckily once I got to bed I pulled out my iPhone and looked at the streaming video of my RepRap and I saw it failing miserably. The barrel had apparently hit the bed and had pushed out of the barrel. For some reason the motor was stuck near the dump location on the bed. Anyway, fail:

A week went by and I rebuilt things, then tried printing (using the new (working) debian package for RepRap Host and firmware), and eventually had it crash and push out AGAIN (in fairness, I was trying to re-use the longer PTFE insulator I’d made). I did witness one issue though.

With the new software, I’d let it specify all new default settings for Preferences (except ones I specifically wanted to set). I noticed that after a layer, Z sounded different.. it didn’t accelerate and decelerate when moving up – it just made a little “beeeeeeep” like sound (presumably moving faster at a constant speed). But later after the crash, I found that it was in a state where even when I used the jog controls to move Z up 10mm, it failed to do so, and instead just made the same beeeeeep sound from the stepper. I forget exactly what I did to reset it, but I think it was strictly jog controls, and then it started responding normally.

I’m planning on trying that new gcode with the old 0806 firmware to see if Z makes the same new sound – I’m thinking it’s just new faster default settings that I can dial back down to speeds that I work OK with.

I did one more thing before finishing this post (I’ve been trying to post this for a while now). I finally took the laptop power supply I’d purchased and soldered on the XLR connector I bought for it – to replace the ATX power supply I’m using.

So there ya go! There’s my progress for the past month or so. Did anyone actually read this far?

(click image for high resolution)

(keep watching that video until the end, to get a true sense of scale)

I built it with Forge, the map editor in Halo: Reach (entirely on an Xbox 360, using the controller.. no computer involved). I did it all by memory – the only measurement I did beforehand was to compare the width of a frame vertex piece to the lengths of the bars between the left and right triangles (and the length of the bars for the triangles themselves). Here are some more pics (again, click the images for high resolution):

As you can see, it’s printing a minimug!

Of course the best way to view it is to download the video straight to your Xbox 360 so you can see it from within Halo: Reach itself.

I’d always wanted to see what my RepRap Mendel would look like to a mouse or ant crawling onto it – some towering, huge structure. Halo let me do that.

Over the past month I’ve made lots of progress with my actual real-life RepRap Mendel (and it’s print quality) that’s worth posting about, but I’m going to break that up into smaller posts since I have so much to document. First, though, I wanted to post this.

And for anyone who doesn’t know what an actual Mendel RepRap looks like, here are two picture of my actual real-life Mendel RepRap (RepRap Mendel?):

Actual progress updates to come soon – stay tuned!

Ok. Around one year ago, wanting to experiment with using Google Sketchup for creating things to print on a RepRap (vs just buildings for Google Earth), I created a test object. I don’t think that at this point I really had any idea what the “resolution” of Makerbots or RepRaps were yet, so I didn’t expect it to come out great.

We have Coke machines at work that you have to pay for (agh!), so there’s always a need to have coins at work. For some reason, while doodling out what this test piece would look like, I made sure it’d have a cylinder in the middle just the right size to hold nickels.

Here’s the object I designed back then (that I hadn’t shown to too many people for a long time):

The circles were pulled out a bit, and the inside bottom part of the triangles was pushed in. I didn’t know if these were enough to cause overhang problems etc, but I did them anyway.

Well, I finally tried printing this. It didn’t turn out that bad for a first attempt.

If you look really closely at the side of one of the pyramid-like points you can make out the hint of the raised circle and recessed bottom parts from the original image. Here’s a picture that kind of shows it, then a 3D cross-eye image that tries to show it too.

And one last picture of it in daylight that looks pretty bad (you can see hints of the problems I’m still having with my x-axis with the loops on the bottom left):

Next up: my RepRap Laptop. Wanting a laptop dedicated entirely to my RepRap, I purchased a Dell Latitude D610 for $179. When it finally arrived I installed Ubuntu 10.04 (10.10 is out but 10.04 is an LTS version).

The first thing I wanted to do was organize my work. Initially I had almost no organization for files I was printing. I was working from a virtual machine dedicated for RepRap work, so in that sense all of my files were in the same place, but they were all just plopped down in my home directory.

I wanted organization, structure, history, and process. So I created a Mercurial repository to hold all of the things I was designing, all of the things I wanted to print, and all of the things I had printed. (Mercurial is a distributed source code control system, much like git. Currently I have only the slightest bias towards Mercurial (hg) over git, but I’m still pretty close to being on the fence between the two.)

I won’t bore you with too much detail, but among other things my repository now contains three main directories at the top: thingstodesign, thingstoprint, and printedthings.

In thingstodesign, I hold projects of my own I’ve started (each has its own directory), where I can keep initial sketches, an idea.txt, and whatever else is relevant. This is one step further along than just being in my thingstoreprap list on my phone.

The next directory, thingstoprint, holds projects of my own (that used to be in thingstodesign) that are ready to move on, as well as external objects I want to print (basically things downloaded from thingiverse or some other 3D site). For things that used to be in thingstodesign, the entire subdirectory is actually moved into thingstoprint. (Remember this is all under source control, so moving things around still feels solid). No lone files – every project (even downloaded) gets its own directory.

There’s a very specific process for thingstoprint projects. They each have subdirectories beneath them named try01, try02, try03, etc. Those directories contain generated gcode, and the reprap.properties file associated with that.

Once an object from thingstoprint is considered “finished”, it’s moved to printedthings. Now that something has moved from thingstoprint to printedthings, an additional subdirectory is created alongside its tryXX directories, called “workingprint”. The contents of that are pretty much a copy of the most recent tryXX directory.

Having this process in place made things much easier. I started moving all of the things from my old RepRap virtual machine into the new repository, which I pushed to my home Linux server, which then is pulled down into the RepRap laptop. I started adding things from thingiverse that I’d wanted to print (and that I believed might print despite my x-axis problem, which currently prevents me from printing complicated things like gears). One less home directory to worry about – now everything is safe in my distributed repo.

One of the things I’d been meaning to get around to printing (to help with my elevator speech) was the coin-based bottle opener. Although I downloaded that into thingstoprint, I also downloaded a derivative part with chamfered edges and a keychain hole that I decided to print instead.

You put the penny in so the metal of the bottlecap doesn’t dig through the plastic.

Here it is on my keychain (it wasn’t easy to get on!):

While the bottle opener was printing in the sunroom (the room near our still-to-be-closed pool, which becomes very cold), I thought back to when I’d propped up my Rovio remote webcam in front of the Makerbot eleven months ago. Seeing prints remotely was nice, but I had to artificially keep the Rovio from driving off the table. I wanted a better solution, and immediately thought about the old USB XBox Live Vision camera I had lying around (they’re around $40 new). One Google search later and I found a quick description of how to get it up and running on Ubuntu with almost no effort, streaming video to a remote web browser.

I can access either static screenshots or streaming video from a web browser. Here’s a view saved from my computer:

..and here’s one saved on my iPhone the next morning.

Portrait view from my iPhone

One of the first things that I read about people printing on their RepRap (other than other RepRaps) was a coat hook. I decided it was finally time to print one. Before taking Alicia and Cara to their gym class in the morning, I started the coat hook print. Here’s how I knew it had completed successfully – an image seen and saved on my iPhone (landscape mode this time):

The build is done!

When we got home we ran in to see the resulting print:

If you look closely you can see that even on a piece as simple as this, I’m still having problems.

And then of course, another disaster. It didn’t start out as a disaster, just as a strange problem with the extruder stopping occasionally.

Maybe there was a jam inside the barrel, I don’t know. Anyway, then this happened:

I’d stripped the gear.

I bought two small and two large gears printed Wade’s gears in the mail to replace this (thanks Tony), which should be here in a few days. That’s why I had time to write this up for you to read.

With respect to the x-axis problem, there are a bunch of things I can try. It feels like backlash – frequent left-right actions cause some accumulating error (that doesn’t happen with the y-axis). I can tighten the belt, grease the rods with silicone grease, etc. But I may remove the belt and just ensure that the carriage smoothly moves along the axis. I don’t think the screw for the extruder mount is going too low into the bar but I’ll check that too. Since I have a few of the nophead pulleys from Neil’s original part shipment, I could try putting that on the X-axis stepper instead of the mcmaster pulley I’m using (meaning I’d have to do some calibration again since it’s 8-toothed while the mcmaster pulley is 10-toothed), but then again there’s a new 9-toothed printed pulley being talked about (but I think that needs a new end bracket..).

Nah, if the Y axis is able to move with a mcmaster pulley, X should be able to also. Maybe it’s the weight of the stepper motor pushing down on the bars, or its inertia resisting left-right motion? Maybe one of the bearings is clogged up and not turning smoothly? Maybe one of the bolts holding the carriage together is too tight? Did I ever file down that X-axis stepper shaft? Or then again it could all just be the belt not being tight enough.

I’m just happy that I’m down to a few identifiable problems between now and me being able to print functional Mendel parts. It’d just have been nice to be able to do that before wearing out one of my extruder gears.

This has easily been the coolest thing I’ve ever built. It’s been unbelievable fun, and I encourage everyone who’s ever even thought about building one to go for it.

Using a MakerBot (that I and a friend Chris built, on loan from work) as a RepStrap, I printed all of the pieces for my Mendel, except for a few. I was helped out over time by mccoyn, spacexula, and work, who provided a handful of parts after I lost possession of the RepStrap.

On July 10th, 2010, I had my first extrusion from my own Mendel RepRap.

To anyone thinking “wow, nine months – that’s a huge amount of time”, don’t be scared off. While the first stage took a long time of many concentrated hours printing all of the pieces for my Mendel on the RepStrap (before heated beds were plentiful, and suffering with the unreliable Makerbot MK4 extruder), the time AFTER that (actually building the Mendel and doing calibration) was far more spaced out over time..

Even so, this has been a great hobby to fill out the last year, and I’m more than happy with my rate of progress.

I’ve printed several watertight minimugs, but no alcohol-tight minimugs. I’m not sure if the particular beverage I’m using is reacting with the plastic somehow, or maybe it’s because alcohol-tight is finer than simply water-tight (which I read somewhere on the internet, so it must be true).

I’ve printed a bunch of calibration objects, then used them to calibrate my machine. It now prints far better, but still no alcohol-tight minimugs. The one takeaway that prospective RepRap builders should learn from this post is this: the tradition of having a minimug be the first thing that you print (and toast with) should take a back seat to printing several calibration objects first.

Ok, lots of talk, no pictures or video so far, and it’s been at least a month since my last post. Here we go. First, I went to Maker Faire NY 2010, along with my Dad (Larry), my brother (Jon), and my baby nephew Blake. It was VERY cool meeting several people who had also built their own RepRaps.. There were Mendels, an incomplete Huxley, a RapMan, lots of MakerBots, and the Fab@Home guys had stuff there too. All very cool.

My brother Jon and my dad Larry

One of the first things I did was to find Tony Buser and see his working Mendel. His Mendel looks awesome, and it works.

Here’s his filament spindle, which I was eager to see in person:

Nicholas Wattendorf was there with his dad Bruce.. They’re in the New England RepRap Group with me, but I hadn’t met them in person yet until this event. Here’s Nicholas with their green Makerbot, doing that stare-into-the-printer that we all do so often:

If I remember right, this was Ethan Dicks in the foreground (I believe he was the one with the first Adrian’s Geared Extruder that I’ve seen in person vs online), and Lambert Andrus from Techzone was behind him:

Here are one of Andrew Plumb (clothbot) building a MakerBot during the show (with his hand on the Makerbot), and Rick Pollack (makergear.com) in the orange shirt in the back right.

I also spent a bunch of time talking to Andy Smith, Tony’s wife Amy, John Abella and his dad, and others whose names I can’t remember, but I don’t have any pictures of them.

The MakerBot booth had a bunch of printed demos out for people to see:

I was able to meet Bre and Zach too – I met Bre when he was showing off the Thing-o-matic, and met Zach on the way into the faire.

Oh yeah, the Fab@Home guys were there too, and they were printing turtles out of spray cheese:

After the first night of Makerfaire I wanted to run home and calibrate my machine, but seeing as how we were in Brooklyn NY and I live in Methuen MA, I’d have to wait. We went back for a second day of Makerfaire (no pics, my iPhone was full), then came home. Soon after, I started back in with my RepRap.

One of the problems that my most-recent-at-the-time heater barrel had been giving me was that it would output smoke. I wasn’t exactly advertising this fact, but I kept a close eye on it, and the first thing I had to do was fix that. At first I feared the smoke had something to do with the heater barrel being too close to my X-carriage (made out of PLA):

I noticed the hole for the PTFE insulator was off center:

..as did others. Originally I thought it was only in the shortened version of Wade’s Extruder (the one made smaller to fit on a Makerbot), but apparently it’s in all versions. Tony Buser made a sideways mount that I’ve tried printing twice that addresses this problem.

The first attempt a while back was horrible (had to abort after a few layers):

While my most recent attempt is merely ugly but might work:

But I’m getting waaaay ahead of myself. Ok, back to the smoke. I took out the PTFE (which I could do, since it’s not glued into the extruder), and tried turning up the heat just a little. This produced enough smoke to convince me that the smoke had nothing to do with my x-carriage – it was instead just a poorly wrapped bit of nichrome wire (and a thermistor that wasn’t in good contact with the nozzle).

So I dismantled the heater barrel and went to start again. For some reason I tried to get the nozzle off of the head of the barrel (can’t remember why I tried that), and I ended up breaking the barrel. It was easy enough to make another, but I didn’t have a spare nozzle handy. (As it turns out, I actually had TWO handy.. I had another MakerBot nozzle I’d bought as a backup backup spare, and Rick Pollack had given me a BigHead nozzle at Makerfaire, but I didn’t remember either of these at the time).

Lacking any memory of having a nozzle available, I decided to create a barrel that was its own nozzle, like the original Mendel plans called for (and like I’d done on my first heater assembly experiment, but had never used). I’d purchased a few 0.5mm drill bits during my last mcmaster purchase, so I decided to give it a try. I went back to the recommended 32mm length, tapered off the edge first to make it pointy (but with a flat end at the end of the taper), drilled the 0.5mm hole (breaking one of the bits in a stupid accident), then drilled the barrel out. It came out rather well:

(then again I’ve only been printing PLA, so I didn’t need to maintain much heat.. maybe ABS would require more metal to keep the heat going)

While the extruder was disassembled I also was able to finally address my spring issue. The springs I bought from mcmaster were too big, and I’d been thinking of cutting them in half but I hadn’t gotten around to it, and was wondering if instead I should just shop around for better fitting springs. Tony Buser had mentioned at Makerfaire that he’d cut his and they worked great, so now I did that.

Of course, there’s something wrong with that picture (which persists on my RepRap still, and will until I take it apart again). When assembling my Wade’s extruder, I had an idea of how it was supposed to go together, and that idea contradicted what I saw in front of me. There are hex-shaped recessed areas on the motor side of the M4 holes for those four bolts. Since the BOM didn’t say anything (at the time) about hex-shaped heads, I’d bought the usual round socket cap bolts. With those round bolts, the only thing that made sense for those hex-shaped recesses was to place trapped nuts inside them. That would mean that the heads of the bolts would be on the other side of the idler bracket, as shown in the picture above.

I even went so far as to helpfully add to the wiki page for Wade’s extruder that the bolts in his picture were backwards, since at first glance it looked like another picture below it confirmed my suspicion that the picture was wrong. I’ve since removed that wiki change, since I was wrong.

What Wade really intended was for cap screws with hex heads, with the bolts backwards from what I have above. The head is trapped by the recesses, and the bolts protrude (for the inset to be slid onto). It seems that that means every time you fully remove and reassemble the idler bracket, you have to take off all of the washers and springs, but at least you don’t have to worry about a trapped nut being pushed out of its recess.

Ok.. So at first, I wasn’t having very good results printing at all (but of course, the smoke had stopped!). The problem was that my Y-axis opto endstop was malfunctioning. The prints were laughably awful.

The problem ended up being that either the cable for my opto endstop is flaky, or possibly it’s the connector soldered onto my y stepper controller. My super-short-term fix was to put a twist tie around the cable, holding it down in such a way that the signal stays solid 100% of the time (I need to make a new cable). I forget where along the line I figured out that it was the cable – it was definitely after some of the pics below.

So, after printing at least 40 minimugs (33 different gcode files, but with multiple copies of some), I was getting pretty sick of printing minimugs. So I decided it was time to print a calibration object to double check my X and Y calibration (I was previously fairly certain that Z was correct).

That first print was still pretty bad but it was at least slightly measurable. I printed four more of these in all, three of them before calibration, and one after.

Before I got to calibration though, I found myself wanting to try printing some other things (knowing they’d probably fail), just to add some variety to this whole exercise. Here were two horrible z-driven-pulley gears, like I wear on my badge at work:

(Again, this was before calibration). Also before calibration, I printed the sad Christmas tree that I’d printed two of on the RepStrap. Those earlier versions (made in ABS) came out great. This uncalibrated version wasn’t great, but at least it looked a bit like a Christmas tree.

It’s hollow by design, so you can fit an LED around a watch battery inside it:

Since things were at least slightly recognizable as objects, and all of this was motivating me to RepRap more than printing more non-alcohol-tight minimugs, I decided to try printing one of the first things that I wanted to design for my RepRap (but that langfordw had beat me to the punch and designed first). I won’t say what it is yet – here’s a picture of the horrible-quality yet functional print:

Can you guess what it is?

If you didn’t watch that video, I’ll tell you what it is: it’s a bag holder. More often than I’d like, I forget on Thursday night to take the trash out to the curb. So often I have several bags to take out, most of which end up packed to the top. I don’t mind the weight of the bags, but these red bag ties they make are like razor wire, digging through my palm as if to cut it in half. This bag holder lets you hold 5-6 full garbage bags without any pain!

That’s the first useful thing I’ve printed with my Mendel RepRap! (But not hte first useful thing I’ve printed with anything, because with the RepStrap I was able to print parts for my Mendel!)

Having branched out from my myopic must-go-with-tradition-and-print-a-watertight-minimug focus to print multiple types of objects, that gave me something interesting to show people at work and elsewhere. I found myself carrying around a bunch of pieces in a large clear ziplock bag:

At some point in this (can’t remember where), I re-adjusted my E_STEPS_PER_MM setting. I measured the diameter of the hobbed part of the M8 bolt, saw 7.33mm and 7.31 mm, went with 7.32mm. I measured some recent stray printed filament, which came in at 0.51mm.. So I calculated an E_STEPS_PER_MM of 1.782303298, which seems to work well.

Ok, so now it was time to finally do X&Y calibrations based on the calibration object I’d printed. I’d printed out four versions of that object, and I measured parts on the first and last of them that should be 10mm, 20mm, and 40mm. Then for each of those measurements I figured out a multiplier for X, Y, and Z that would correct those values (although I didn’t use the Z value in the end). I averaged them together, looking for values that were out of whack and giving weight to objects that printed better, and came up with my final values.

In my configuration.h I’d originally had for x and y:

// For x and y, steps/mm = 400/(16.1798*pi), where
// 400 is the number of steps and 16.1798 is the
// radius in mm of the McMaster 57105K11 pulley.
// Answer: 7.8693


After calibrating, I now had:


//#define X_STEPS_PER_MM 7.8693
// Calibration experiments said multiply this
// by 0.9165
#define X_STEPS_PER_MM 7.2122
//#define Y_STEPS_PER_MM 7.8693
// Calibration experiments said multiply this
// by 0.9267
#define Y_STEPS_PER_MM 7.2924


Just for my own record, I’ll include the comments I have about Z_STEPS_PER_MM, but I didn’t change them here, even though the calibration experiments said to multiply it by 1.0193. This was my commented out original old calculation plus the brute force observation that I’d done back in July.


// For z, steps/mm-of-z-axis is
// (RPdiam / McMdiam) * (400 / 1.25),
// where RPdiam is the diameter of the
// RepRap'ed leadscrew pulley (which is
// ROUGHLY 1 1/8", or 28.575mm),
// McMdiam is the diameter of the
// McMaster 57105K11 pulley (which
// is 16.1798mm), 400 is the number of
// steps, and 1.25 is the pitch of the M8
// threaded rod used for the leadscrews.
// Answer: 565.1491
// ...
// ...but through experimentation by watching
// how many times the bolt went around,
// I ended up with:
//#define Z_STEPS_PER_MM 670
// 670 WAS GREAT but after 30mm, just a BIT too low
#define Z_STEPS_PER_MM 672


My X and Y calibrations now changed in the firmware code, I recompiled the firmware, uploaded it to my motherboard, and printed my fifth calibration object.

This one was great.

If it’s not clear what that calibration did, let me state it clearly. Previously when I’d tell it to move in the X direction, it would move too far. Similarly if I told it to move in Y, it moved too far as well.

This would certainly help explain not having watertight minimugs with the default settings:
1) Base of the mug is printed larger than it should be
2) Thickness of the printed plastic is still the same (same sized nozzle)
3) Thus, more space between the pieces of plastic that make up the base.

I tried printing a minimug with the default settings (no changed infill settings, etc – just the new calibration). Unfortunately I think this time the wire for the Y-Axis opto endstop came loose so the top was offset, but it was certainly watertight, even without setting changes.

The next day, Alicia and I printed two minimugs that looked like great candiates for the toasting ceremony. Not wanting to mess with anything, we didn’t try filling them with water first. Actually the only reason we printed a second is because we were waiting for Laurie to come home to see.

With default settings:

Laurie and I tested them both, and they both leaked alcohol. There’s still plenty of room for improvement though – this was just using the default RepRap Host settings – only 1 shell, the default infill, etc.

About a week later, I wanted to scratch an itch before going back to honing infill settings to try to get a tighter minimug. I wanted to print out an object that I designed.

Now I’d designed one test object over a year ago with Google Sketchup, but that’s way too detailed to print out on the machine the way it is now. So instead I did a simple object in openscad. This is actually a part of something else I want to build, but I won’t go into the details of what it’s actually for in this blog. Suffice it to say, this is a cube with three 8mm cylinders subtracted from it. Three holes go through the cube, one affecting each face, and the tunnels don’t intersect at all.

That’s supposed to be a hole going vertically down through the cube in the last pic, but that hole ends up poorly every time I print it.

Here’s the object in front of the openscad source that created it:

I needed seven more of these, so I created an RFO file that positioned 7 of these on the same bed. Unfortunately I spaced the ones on top too close together (actually looking at the next piece, I don’t think I did), and that combined with possible x-error accumulation seems to have led to them all melding into one piece. (If I do another sheet like this, I’ll add extra home commands by hand that home after each object during each layer).

I printed three more by hand, one at a time. Some of those turned out excellent.

So, there ya go, I’m making great progress. It’s certainly more fun carrying around more objects than just mininugs.

I finished this blog post before trick-or-treating! Woohoo! (I started typing this two days ago on Friday). Ok one last picture to enjoy: Alicia said that this looks like an elephant:

At the time of my last post, I’d just had my original non-geared Mendel extruder push the heater barrel out of the PTFE which was JB-welded to it (preventing me from easily fixing it). Here was what the barrel looked like:

And here a picture of the whole thing just lying on the bed:

I could have heated up the barrel outside of the PTFE to melt the PLA, pulled it out and cleared out the barrel the best that I could, and then use a soldering iron to melt some of the PLA in the PTFE, but I’d still be left with a PTFE insulator whose inner threads already deformed enough to let the heater barrel escape.. so I’d still have to try removing the PTFE (even though it’s JB-welded into the extruder). I’ve read some hints that that can be done with a chisel, but that didn’t sound too fun.

While I still may do some repair on that extruder down the road (as a backup), luckily I didn’t have to go down that road. Spacexula offered in the comment section of my last post to send me the printed parts for a Wade’s extruder (since I had the rest of the hardware ready already) as long as I agreed to print out and give away two once I’m up and printing. Since I was going to do that anyway, it was easy to say yes. One quick paypal for shipping later, this arrived in the mail:

(Thank you, Neil!) The four parts on the right were the parts for Wade’s extruder, while the others on the left were extras worth having spares of to help fill out the box and justify shipping. More pics:

Shiney!

Those bottom two holes on the last picture are where you screw in long M3 bolts that go through the PTFE insulator, so you don’t have to glue it on, so I won’t be in the same situation I was in with my last extruder.

One other picture I wanted to show (ok, two) before going on was the cool look of how the bottom flat part of the large gear looks from how this part was printed (on a shiner surface than the masking tape I’m using, that’s for sure.. Probably kapton or PET, on a heated bed?):

Ok.. So here’s what the back of the extruder looks like when assembled.

The idler bracket is the piece on the right, held on by four screws. There are supposed to be springs on there – the springs I bought from McMaster must have too many coils or something, because when I had the springs on there was no way the bolts would reach the trapped nuts on the other side.. I need to find suitable springs, but the springs aren’t 100% necessary (they even out pressure when the diameter of the filament changes or turns, etc).

The nut shown above was a temporary M8 nut I used initially until I had everything going, but I eventually replaced it with a nylock M8 nut so it’d stay on through the vibrations.

The big mistake here was even mounting the motor at this point at all. You need to mount the extruder on your Mendel first, before mounting the motor within it, because the screw sits directly below the motor (which was actually a problem for me, fitting the motor in, but I got it to work).

More pics.. Here’s the front of the extruder. The stepper motor shaft (with a flat filed onto it) can be seen in the middle of the small gear on the right. That turns the large gear on the left, which has a large M8 bolt trapped in it (the same one you saw a nut on in the back picture). Two skate bearings in the structure hold the nut so it can spin. The nut has a knurled notch cut into it, which I don’t think I did a very good job of, but it does the job at least for now. The plastic to be melted gets pushed between that M8 bolt on the big gear, and the third skate bearing in the idler block which is held on as seen in the pic above (with the four bolts that should have springs).

Here’s a close up of the bolts holding the PTFE insulator into the extruder:

And here’s a picture showing the two gears meshing from the side. Here you can see the filed down stepper shaft (knew I’d use that skill again), and the grub/set screw going through the trapped M3 nut in the gear to dig into that flat in the shaft:

I put it all together (without the heater barrel assembly) to see if the M8 bolt I’d cut could grip any plastic at all. It turns out it was good enough. Here is the motor just turning the gears:

…and here is the extruder actually pressing plastic filament through the extruder (again, without the heater barrel):

Ok so now I needed to create another heater barrel (so I could leave the one in my original extruder intact). I had two unsuccessful attempts at drilling out M6 rods – they came out way off to the side at the bottom. I spent a few days fixating on finally getting around to buying a mini-lathe, until I read up on what the differences between a wood lathe and a metal lathe were, and saw that a metal lathe would cost me at least around $400-$500. So I resisted that desire by doing what I’d attempted to do before – hollowing out a heater barrel by putting the barrel itself in my drill press, and lowering it onto a fixed drill bit (now an M3 bit, since I just purchased a metric drill bit set recently.. no more converting to imperial measurements).

With the barrel successfully drilled, it was time once again to wire up a heater barrel assembly. I’d previously made a checklist for myself of what tools/parts to have on hand to build one, but that was for the MakerBot RepStrap, so I made another for rebuilding the heater for my Mendel:

..except that those hose clamps don’t fit in the x carriage..

This time it took me 1 hour 12 minutes to get to a barrel in a nozzle wrapped with crimped nichrome, with a thermistor connected, and even wrapped in ceramic tape.

There was no convenient place on Wade’s extruder for me to mount a piece of stripboard with compatible headers for connecting to my Mendel, and I didn’t have the desire to spend lots of money on shipping for a few proper headers with polarized locking connections for this new extruder, so I just used some breakaway headers and created a small unpolarized plug inline to plug them into (which I’d later connect with tape):

I connected it all up again, and finally, I was extruding!

As I said, I was not using the right E_STEPS_PER_MM yet, so the speed was off.

Now with a geared extruder, I printed one mug that filled up 90% with water but then leaked (a JeffTry30 print). Then I did another of an earlier model (JeffTry22) which always looks good but has a horrible leaking bottom. This one didn’t print its shield well, so it resulted in burned blobs everywhere while it tried printing and kept dragging plastic where the shield should be.

I think I need to try using a hairdrier to heat up the bed a little before the first layer goes down, or adjust my z-opto-flag again to mash the plastic into the bed more.

Then one day (I don’t remember how long after that) I read that someone said the value usually used for E_STEPS_PER_MM for a standard Wade’s extruder was actually 2.02, which was larger than what I’d obtained from the spreadsheet I had. That night I got home extremely late, everyone was asleep, and I decided to upload new firmware with the correct value and try printing again.

Here’s a picture of the bottom of the mug being made.. Note the brown spots, because there was way too much plastic being output and the nozzle would plow through it, burning it at points.

Again the shield wasn’t printing correctly but I let it go on anyway. Here’s the ugly result, with a very thick/tight bottom:

That was also a JeffTry30 (but again, now with 2.02 for E_STEPS_PER_MM). I went into the bathroom, and filmed this:

Sadly, the next morning was not a time for celebration. I actually tried filling the mug with my as-of-yet-undisclosed drink, and it sadly spilled all over the table. Now would be a horrible time to find out that alcohol dissolves PLA or something, wouldn’t it?

Haven’t had time yet since then to print another, and I’m going to be slowed up a bit by events over the next few weeks.

One of which, by the way, is Makerfaire NY, on September 25-26, 2010. I’m up in the Boston area, but I’ll be heading down Friday night (the 24th) with my Dad, we’ll stay at my brother’s, and the three of us will check it out Saturday. Mid-summer I’d considered bringing my Mendel down, but I deliberately let the deadline for registering pass, which I’m glad I did because while deadlines do help motivate progress on projects, they also tend to add stress, and in this case I’d rather see others’ RepRaps and walk around the faire than stand in a booth explaining why I still don’t have it calibrated correctly for a watertight minimug.

So there you go – the most recent state of my Mendel. More later (after I’ve had a few weeks to get a few hundred hours of Halo: Reach under my belt, which is another distraction, but a welcome one).

Here’s the first of those two minimugs:

Look at the bottom of this mug:

Then I checked to see if it could actually hold water:

Then I made another mug, this one was much better. JeffTry28:

Check it out! It actually held some water!!

Then I added even more.. As you can see, I got to around 80% full before it started leaking:

The next day I tried printing more mugs, none of which really came out well. This one looked like Eraserhead:

..and then tragically, in front of a bunch of witnesses, the extruder barrel pushed right out of the PTFE, ending the life of this extruder:

I haven’t yet taken it all apart to see how bad things are. I knew the PTFE would give way at some point.

I’ll post more details later. If the PTFE glued into my extruder isn’t ruined, I’ll try repairing it, but if I can’t, I may use this as an excuse to just buy the printed pieces to a Wade’s extruder from Tony or someone (I have all of the rest of the pieces in an unopened McMaster box).

I filed a bug about the problem in the RepRap Host software which was leading to hollow prints. Basically the mistake I was making was assuming that the “Extruder0″, “Extruder1″, “Extruder2″, and “Extruder3″ tabs in the RepRap Host preferences window corresponded to multiple physical extruders. They don’t. They correspond to extruder PROFILES, each of which maps to a physical extruder (they can all map to the same one).

I’d changed the NumberOfExtruders preference field from 3 down to 1, because I only have one physical extruder on my Mendel. Bzzzz.. Wrong. (I think the UI could be more clear on the distinction, but that’s not the only problem).

Here’s how it actually works.. Each “Extruder” tab (with all of its’ corresponding values, such as temperature, speed, etc) represents an extruder profile. So you could have one for PLA, and one for ABS, both of which have different values. By default the NumberOfExtruders value is 3, and the first three extruder profiles are:

Extruder0 (“PLA”)
Extruder1 (“PLA-support”)
Extruder2 (“PLA-infill”)

When you print (usually to a gcode file), you get a choice of which profile to use. Here you’d choose PLA.

But if you look at the preferences within an Extruder tab, you see there are three fields that refer to extruder profiles by name:

• ExtruderX_MaterialType(name) – this is the name of this profile.. Extruder0_MaterialType(name) is “PLA”.
• ExtruderX_SupportMaterialType(name) – this is the name of the profile to use to print support material
• ExtruderX_InFillMaterialType(name) – this is the name of the profile to use to print infill (the inside of an object)

…but when it looks for those named profiles, it only looks up as high as the NumberOfExtruders preference field specifies.

So, I had set NumberOfExtruders to 1, I went to print, I printed with the only extruder profile available extruder 0, “PLA”, because Extruder0_MaterialType(name)=”PLA”. But during that print, when it made it to the point where it would print infill (where there was a solid, which in the case of a minimug is the bottom of the mug), it would see that Extruder0_InFillMaterialType(name) was “PLA-infill”, so it looked for which extruder profile had the MaterialType(name) of “PLA-infill”. That should have been extruder profile 2, but it didn’t get that high, because NumberOfExtruders was 1, so it didn’t find it. At this point, the RepRap Host software didn’t have an extruder profile to print the infill with, so it didn’t – it left the infill space completely empty.

So the inside of the bottom of my minimugs (and the solid part of any of the gears or other pieces I was trying to print) were coming out hollow.

When I realized this, I couldn’t wait to try it out, but I couldn’t actually print until Friday evening.

My first approach was to change Extruder0_InFillMaterialType(name) from “PLA-infill” to “PLA”, and leave NumberOfExtruders at 1.

This yielded an absolutely beautiful print. Sadly, it still wasn’t water tight, but it was beautiful. Pics and video say it all:

(click image for unscaled image – scaling ruins the 3D effect)

Ok.. So one point worth mentioning about the above before going on – I said you could see both rings that make up the minimug.. That’s actually because I had Extruder0_NumberOfShells(0..N) set to 2.

I tried testing JeffTry22, but sadly it wasn’t watertight.

Encouraged though by the infill discovery and the knowledge that all of my prints should be much better now, I decided to try printing the large 39-tooth gear for Wade’s extruder. That print started showing serious problems almost immediately, but I let it go so I could study the results. It would start trying to print the outer teeth of the gear, going very slowly on each gear tooth, and by the time it completed the circle near the first tooth the print head didn’t line up – it was more like an inward spiral than a circle. After that point (on the same layer), the infill would start to print, offset by a huge amount (it was way to the right of where it should be). Once the layer finished, it’d home, and lay down the next layer fine, but with the same consistent problems as before.

(Sorry that this next video is truncated..)

I figured it was clearly an X-axis problem of some sort, where the X-axis was accumulating error during a layer (which is later corrected while homing). I thought perhaps I was missing steps. I tried increasing the current on the X-axis stepper controller board, but didn’t rerun this particular gear print yet so I don’t know that it fixed it.

I thought that the same x-skipping (if that’s what it was) might explain why the two circles that make up my minimug walls weren’t exactly concentric, but rather they kissed on the left side. That would explain the “gap” between layers that I was finally able to see in JeffTry22 above. I DID try printing other minimugs, and looked to see if the circles were any more concentric than they were – they weren’t (that I could see), so that’s the most verification I’ve currently done as to whether turning up the potentiometer actually did anything meaningful.

It could also be the tension on the X-axis belt (too loose? too tight?), or maybe the bearings aren’t turning well after the rust-like issue I’d had before (although the rods are clean and silicone-greased, maybe the bearings aren’t smooth anymore?).

Or, it could be the filament being tight (which it was during the end of that gear print – I hadn’t fed enough spare line out by hand), and rubbing up against the threaded rod.. (I have some tape on it now to make it smoother..)

So realizing that the effect of any X-skipping seemed to matter most with big complicated prints, I figured I’d try printing out the small gear (which hopefully wouldn’t be affected much if at all), and later I’d try to artificially increase x-skipping on minimugs by trying to print four at once.. But I’m getting ahead of myself.

Here was the result of re-printing the small gear. Much better with infill, but still not great:

After that, I decided I’d save my preferences file (I saved away JeffTry22’s, that’s for sure), and try starting from scratch, using multiple extruder profiles (instead of just the one, pointing at itself for infill), and see how that goes.

The minimug came out horrible. It printed MUCH faster – I guess I’d forgotten that I had the speed set lower than before (which is funny because a student at work who had built a Darwin a while back saw a previous video of my Mendel printing and remarked that it was much faster than the Darwin used to print). I haven’t tried going back to 2 shells at the same “slower” speed (1000) but keeping the 3-profiles, to see if I can get a JeffTry22-equivalent with three profiles. What I did notice though was that the infill was far more sparse with the 3 profiles (as you’d want for anything other than a water-tight object.. infill is supposed to be just a support lattice inside a structure), so again maybe I should go back to just one, and try to tighten that up.. (I’d tried a gap of like 0.1 instead of 0.7 and it caused an array index out of bounds exception, so I reverted.. maybe I went smaller than the default extrusion size or something).

Here was that minimug attempt with the faster speed:

The messy print on the left in this next picture is the result of reverting preferences.. The print on the right is old.

After changing some settings back to what should have been correct, I tried printing 4 minimugs at a time, for the hell of it. Yeah, it didn’t go so well. An error in one of the three can carry onto the others, if it grabs a glob of molten plastic and drags it across, etc.

(I also left this completely unattended, so bad prints look worse because they build on top of failed bases, etc).

And finally, here’s a quick video that shows the extruder actually working correctly, digging notches into the filament to get a grip on it. The youtube compressed version doesn’t show it quite as well as the original, but I’ll include it here anyway:

That’s it for now! Go back and look at those JeffTry22 success pictures above – that’s what I’m remembering. (I actually lost count of how many successful ones of that I printed).

I’ve been printing a lot, trying to get better. Progress comes and goes. There’s joy and disappointment. But the march continues.

Lots of pictures and video – as much as the huge post a few posts ago. Let’s start with how I got to even be printing in the first place.

Before the first minimug of the last post, I was waiting on a new higher-torque stepper motor to arrive. It arrived:

According to the reprap.org Stepper Motor page that model stepper motor should have a 3/16″ diameter shaft (4.7625mm, which is smaller than 5mm), which was disappointing because I thought it might complicate cutting splines onto the shaft, but I went with it anyway. I was pleasantly surprised to find out that the shaft was in fact 5mm:

Great.. So I went about cutting splines into the shaft, just as I’d done on the previous stepper motor, using the same rig.

Here is the old motor and the new motor side by side. Guess which has more torque?

Unfortunately, when I went to install the stepper motor, if I pushed it right up against the plastic for mounting, the part of the shaft that was splined was actually not quite in the center.. So plastic coming down through the hole in the top of the piece wouldn’t be lined up with the splines. In fact, this may have even been the case with the original stepper motor ( ), where perhaps only part of the splines were reaching the plastic. I still think the higher torque was required though, after seeing the rest of what I’ve gone through.

So I went about spacing the stepper motor away from the plastic with washers, which was not terribly fun. It would have been easier if I’d just removed the extruder piece from the carriage and held the whole thing sideways, but I didn’t want to have to worry about the trapped hex nuts falling out of their plastic spacings, so instead I spent way more energy worrying about dropping washers everywhere.

Anyway, I finally mounted it, and after a brief panic when it didn’t initially work, I soon got to this:

Successful powered extrusion! I can’t remember if it was the first try after that, or maybe one or two more, but then came JeffTry15 (my first minimug, from the last post).

Here was a video taken during that momentous print:

The quest for the water-tight minimug started there. Part of the quest is for tradition – I want to toast my successful printer with a thimble-sized shotglass that it itself made. Another part is functional – if I can’t print a minimug with enough precision to hold water, how can I print a functioning geared extruder to replace this one? That last sentence would have me wondering, but I’m getting ahead of myself.

Here was minimug #2 (on the left), next to minimug #1 (on the right):

Here they are on another surface, swapped (#1 on left):

…and on another surface:

On minimug #2, you can see the bottom layer here because it was off, but not off enough to be outside the print.. The bottom layer is very thin, compared with the rest of the layers (and in PLA, it looks like the only layer that has any chance of being water tight).

There was promising set of preference fields in the RepRap host software that I thought would help in making a water-tight base, but they didn’t pan out (I’m all ears if someone has suggestions):

FoundationLayers – (The number of layers of material to put down under the object being built before building proper starts.)
Extruder0_ExtrusionFoundationWidth(mm) – The gap between the infill zig-zag pattern used to fill the interior of the foundations (if any).
Extruder0_ExtrusionLastFoundationWidth(mm) – same as above for last foundation layer only

When I tried setting FoundationLayers to 6, the RepRap repeatedly homed 6 times, each time moving up a bit, with basically empty layers (no “foundation” was printed). Then plastic extruded wouldn’t stick to the base, so I had to cancel that print (and the idea of using those fields).

At one point (probably later than this, I can’t remember) I tried using skeinforge again with tonokip’s mendel skeinforge settings, but without the “shield” behavior that the RepRap host software usually does, it didn’t manage to extrude the first layer well and I went back to the RepRap host software.

So anyway, after the 2nd print I was able to make my third minimug, which was probably the best one yet.. To make this I took the JeffTry15 file that made the first minimug, copied it, and by hand added four lines before the Layer1 comment:

G28 X0 ;set x 0 - added by JLK by hand
G28 Y0 ;set y 0 - added by JLK by hand
G28 X0 ;set x 0 - added by JLK by hand
G28 Y0 ;set y 0 - added by JLK by hand

This was necessary because after going to the dump location and purging, my Mendel was having some strange problem where it wouldn’t go to the correct X location. I can’t describe it – X travel usually works fine, but after this particular move, it would often (almost always, if not always) be wrong. So adding the above explicit home command (even twice for meaningless good measure!) fixed that problem.

I also put some tape over my Y opto endstop, on the theory that it was too reflective and that was screwing up Y-axis homing every once in a while. It did seem to fix it (I didn’t see that occur during the next print), but I have seen it miss Y again since then, so I’m not 100% sure.

Anyway, the explicit homing code added to the gcode file, plus the y-axis optoflag tape, yielded this – minimug #3:

Third minimug:

It still wasn’t water tight. The next two prints were horrible..

Fourth minimug:

The fifth was worse:

I filmed this next video lineup/diary right as the sixth was beginning to print (in the dump/purge phase):

This next video, which was filmed during the printing of minimug #6, is an example video I’ll probably use when trying to describe to someone what a RepRap is, what I’ve built, and what it looks like when printing (at least for now):

The resulting minimug #6 was indeed better than #4 or #5, but showed signs of burn PLA.. I need to start keeping track of each print with its temperature and settings, etc, like a scientist.. (well, I’m trying through these videos, but I can’t remember what the temperature was for that print):

(That tall L-shaped thing to the front-left of the cylinder in those pictures is the “shield” that the RepRap host prints out every layer, to ensure there’s plastic in the nozzle before printing)

Another lineup of mugs (mug-shots.. aaaahaha!! ha! ahhh… ha.. hmmrph.. cough… (crickets)):

After this many minimugs, I was itching to try printing something else, if not just to eliminate the possibility that maybe making a water-tight minimug out of PLA was tougher than creating solid usable parts for Wade’s extruder. So I tried printing nophead’s beefed up version of the idle bracket for Wade’s extruder. The result was not good:

I tried printing another one, which came out worse:

…and here they are, side by side, with the 2nd worse one on the left:

Back to minimug attempts, and ended up with a few like this that didn’t even get to be minimugs:

Another, larger, lineup:

And then, just to satisfy my curiosity about minimug #7, I taped the bottom and went to see if it could hold any water at all.. It was cool to try, because when it’s under water it’s almost invisible (just like when they dip plastic rods into water in a science museum exhibit to teach about light refraction):

Ok, maybe it wasn’t invisible, but it was cooler than I expected.. I forsee someone uploading a small water pistol to thingiverse (if that doesn’t run afoul of the general aversion to gun-related anything in the RepRap project, or any such feelings that might exist at thingiverse).

But I digress. Next I tried printing another piece of Wade’s extruder (since my first part went so well). I think it’s because when you’re in the middle of a run of failed attempts at something, there’s a desire to try something else, if not to just avoid the “insanity is trying the same thing repeatedly and expecting different results” trap.. Even though yeah, I was making parameter and temperature changes each time, so it wasn’t actually the same, it still felt the same at the end when you had a leaky minimug.

I tried printing the smaller of the two gears for Wade’s extruder (again, I went with a variation by nophead, this one having an area to slide an M3 nut into for a set screw.

I gave that one another try, and this time the latter print turned out better.. It’s still unusable, but at least this time it looks like a gear and you can see more than one tooth!

Undeterred by my lack of success (which should have pushed me back towards experimenting with different temperatures, remounting the extruder several times, and messing with print settings to get a perfect minimug), I decided to try something even crazier – see how far it would make it printing out a whole sheet of Mendel parts from one of the RFO files that ships with the RepRap Host software.. (ok maybe this one was just wanting to see what the UI looked like after I clicked the “Load RFO” button).. I loaded tray 1, removed the pieces that I absolutely didn’t need (the belt splitter jig pieces), and tried generating gcode (which took a while). Here was what the software showed me the build would look like:

But after printing what actually might have been an almost workable layer for the first piece or two, it lost any ability to extrude enough plastic (temperature problem? jam? who knows), and this was the result:

Yeah.. So, couple that with the fact that I knew I shouldn’t be wasting time on that yet because I wasn’t even there quality wise, and I headed back towards minimugs.. Except I didn’t actually get to making another mug yet (before the time of this post, anyway). I wanted to try something different, and one of the questions that had been nagging me was whether ANYONE had made a successful minimug out of PLA with the RepRap Host software.. (maybe everyone had been using ABS with skeinforge?).. So I decided I’d do what I’d told myself I didn’t want to do yet – try extruding ABS.

The problem was I didn’t want to get some PLA/ABS mix globbed up inside the extruder, but it’s not the end of the world if that happens, so I gave it a go (I’ve certainly printed enough ABS parts out on the Makerbot – that’s what most of my Mendel is made from!).

My first problem was what to print on.. On the Makerbot I’d found that double-sided tape on the acrylic bed worked ok.. I had some of it around, and despite my uneasy feeling about it, I tried putting it on the MDF bed:

I was able to extrude some ABS, although not a hell of a lot, so I shouldn’t have even tried printing but I did.. I guess I didn’t press down the tape well enough and it floated higher than the masking tape usually does, because this wonderful thing happened:

At least I have some scraps of ABS to remind myself that yes I’ve tried ABS on my Mendel:

That’s basically where I left it.. Next time I turn on my printer I either have to do more ABS experiments or flush the ABS out of the system to get back to PLA extrusion (which is always fun because of the temperature issues, etc). I’ve got this haunting feeling that time is creeping up on me, and that I’ll have to rebuild the heater barrel again someday (based only on my Makerbot experience, but that was usually after printing dozens of parts, so I’m hopefully nowhere near needing to do that yet). I can’t wait to get to the point where I’m printing out good usable solid pieces from PLA, like I did when I finally printed my extruder piece out of PLA back in December.

I’m tempted to ask people for advice (ok, screw tempted – feel free to submit advice in the comments!), but I shouldn’t need to – I’m my own source of advice! I’ve done this, with this very spool of PLA! The differences here are:

1) Obviously, it’s a different printer (Makerbot vs Mendel), with different quirks
1a) The extruder strength is different
1b) The extruder grip (gear vs splined shaft) is different
1c) The idler wheel spacing is different (known spacer bar for Makerbot, unknown for me)
1d) The idler wheel spacing will slip more over time here (fixed by other extruder pieces)
2) I’m using the RepRap Host software instead of skeinforge to do my slicing
3) I don’t have any idea which thermistor I’m using, so I haven’t changed firmware to reflect which thermistor I’m using, so the temperature numbers won’t necessarily be the same
4) Maybe moisture or age has affected the PLA (I doubt it, but it is a difference, and people have talked about it).

So, suggestions, stories of success/failure with others’ water-tight minimugs, etc are all welcome. While typing this I did a google image search on “minimug success” and one of the images was this beautiful minimug (looks like ABS) that Zach made back in 2008. I’m drooling. I wonder what size nozzle that was? Bigger?

That’s it for now!

Four pics:

More in a later post, with all of the boring video and pics leading up to that. But for now?

MY PRINTER IS PRINTING!!!!!

August 3rd, 2010, first print. JeffTry15.

Today I ordered a high torque stepper motor with a 3/16″ round shaft (Lin Engineering 4218L-01-10) for around $10. I’ll cut splines into that shaft too (as I did with this one), and hopefully get enough torque that I can dig into plastic enough to get consistent extrusion so I can print a geared extruder (or, one thing at a time, print anything).

The new stepper motor is due to arrive Tuesday. I won’t be doing much until then.

All of that said, here are a few pics and video clips of some of my print attempts up to this point (after a few gratuitous 3D pictures of my Mendel):

NOTE: With the lazy-eye 3D pics, I’ve found it’s best to click on the pictures first, then try doing the 3D thing. Wordpress tries scaling these to make them bigger, and in this case bigger is not better – it makes it very difficult to line up the images, and then there are scaling artifacts.. Click the pictures so they’re in their own un-scaled original forms first.

I love this first one – note the wires, the pool in the back, the table beneath it, the foremost threaded bar with the power cables on it, etc.

Look at this next one and see if anything looks “wrong”:

It took me looking at that above 3D image to realize that one of the M8 bolts on the top had almost come off from vibration. I had the actual Mendel right in front of me and didn’t notice it, but the 3D picture had me studying every bit of it and I noticed.

Here’s one last 3D pic:

Ok.. Here was video of JeffTry6, where I briefly got optimistic enough that I almost sound like that “double rainbow” guy (shiver):

Here was the result of that:

..and me talking about that:

So then I went about doing the math to determine what the number of steps/mm I should have for Z, and for that matter, for X and Y. I have McMaster pulleys (McMaster part# 57105K11) for my X, Y, and Z stepper motors, which have a larger diameter than the printed Mendel pulleys. For X and Y it’s easy:

// One step is the circumference of the pulley divided by the number of steps)

1 step = (McMasterPulleyDiameter * π)/ 400 mm

1 mm = 400 / (McMasterPulleyDiameter * π) steps

(where the 200 step (1.8˚) motors are in half-stepping mode, so we use 400)

That means my X_STEPS_PER_MM and Y_STEPS_PER_MM are 7.869315719200254 (I put 7.8693).

For Z there are two gear diameters and the leadscrew pitch to deal with too. For Z, my math was:

// 1.25mm pitch screw, 1 full turn, 1.25mmz

1.25 mm-of-Z-travel = (RepRapLeadscrewGearDiameter * π) mm-of-belt

1 mm-of-belt = 1.25 / (RepRapLeadscrewGearDiameter * π)  mm-of-Z-travel

Then combine that with the previous equation for 1 mm-of-belt from above:

// Same as above

1 mm-of-belt = 400 / (McMasterPulleyDiameter * π) steps

400 / (McMasterPulleyDiameter * π) steps = 1.25 / (RepRapLeadscrewGearDiameter * π)  mm-of-Z-travel

which reduces to:

1 mm-of-Z-travel = (RepRapLeadscrewGearDiameter / McMasterPulleyDiameter) * (400 / 1.25) steps

Maybe my measurements were wrong, or I’m taking the diameter of the wrong part of the gear.. My X/Y value seems ok, but my Z value didn’t work in practice. McMaster’s site says the diameter of that pulley is .637″ (16.1798mm). I measured the RepRapLeadscrewGear at around 1.125″ (28.5750mm). That gave me 565.1491 steps of the Z-axis motor to move the X axis up or down 1mm. So I set Z_STEPS_PER_MM to 565.1491 (in firmware, and also in the Preferences page), and it didn’t turn out right. It turns out the correct value through experimentation was 672. If someone wants to tell me where I got my math wrong on that one, I’m all ears (but again, it could just be the wrong measurement). And by the way, thanks to Laurie for verifying the math by solving the problem independently from me so we could compare our results.

Here’s how I determined the Z_STEPS_PER_MM through experimentation:

At some point after this I realized to my shock that when the nozzle moved towards the right on the X axis, the nozzle raised higher and higher above the bed. I’d previously spent time making sure this wasn’t the case, so I worried about how that had happened. The first thing I did was check the bed height with the spacer piece, and determined that the bed was correctly leveled. Then it hit me and I felt crazy for not having seen it immediately – the right leadscrew was somehow now a few turns higher than the left leadscrew. I think this happened when I’d been working to fix the Z axis problems I had a month or two ago. Anyway, I loosened the Z belt, adjusted it meticulously, tightened everything up again, and that’s all fixed now.

Then I proceeded to do more attempts at printing. JeffTry10 didn’t look very good at all..

Then another..

The best example of the fact that I’m not consistently extruding but rather dribbling with some slight push was this attempt at printing a 40mmx40mmx40mm cube, which I only let go for maybe 2 layers before aborting:

Before deciding to buy a new stepper motor with higher torque, I figured I’d give it one more try, this time changing the extruder firmware to use full steps instead of half steps, which I think should increase the torque. I certainly got more plastic out, but as you can see, it’s still not extruding correctly:

Here’s one more 3D picture of that print attempt, then a picture, then video:

That’s it for now. More next week!

There is video of that a few photos/videos down from here, but as usual I’ll show what led up to that first.

I’d only had two times last week that I could play with my RepRap and I was having problems getting it to fully extrude on its own. The stepper motor seemed very weak..

Here it was, thinking it was printing a mini-mug:

Here’s a video showing the extruder appearing extremely weak, unable to push out plastic.

Then I started getting much closer just by adjusting the motor mounting while it was trying to extrude, so I could see where it could grip. I still wasn’t there, but I was closer:

3-d cross-your-eyes picture of the plastic in the extruder (click for unscaled picture, which works better):

I’d posted to the reprap forum about my weak extruder problem and Wade said he’d had the same problem, and suggested cranking up the current on the stepper motor and slowing the extrusion speed. I had already tried turning the trimpot on the extruder board with no success, and remembered reading on the extruder controller page that the trimpot wasn’t currently used.

It turns out that it can be used by the FiveD firmware if you issue the right “M” command (M113). M113 without any arguments causes the trimpot to be read right then. I’d you supply an argument, though, you can specify a value right there in the gcode file.

That revelation led to one long uneventful video that I’ll spare you from, and then…. to THIS:

Here is my RepRap’s first printed attempt at making a minimug:

Here is the entire removed top bed with the failed print:

And here are two cross-eyed 3d pictures of that print (click for unscaled pictures which again work better):

When peeling it off of the bed it was interesting to see that the bottom layer that was really flat (I think I trimmed my z opto flag about 0.5mm too short) actually stuck together, despite the thrashing that the failed build did to the rest:

So now I think I just have to find the right combination of: a) the correct spacing between the stepper and the bearing, b) the right PWM setting to use, and c) the extruder speed. Not sure on how exactly to change c yet.. Changing the gcode directly probably affects the rest of the build – when I was using skeinforge on the Makerbot I had to change something pre-rendering. Eh, we’ll see.

BUT NOW, I’M PRINTING!!! Woohoo!!!!!!!!!!!!!!! Now to just get something to print correctly…

..and I’m actually at the cusp of printing.. So close I can literally smell it.. but I’m in a whole different category of problems now – problems getting things to print, not problems building the machine! So that’s actually one reason I want to post now – to cover all of the progress up to now so I don’t have to do it later. And there’s a lot to cover.. Huge media bonanza in this post – enjoy.

Ok, where to start.. Well, in my last real post I gave a quick preview of two youtube videos, so I’ll include them here. The first one shows a strange (new, replacement) problem I was having with the leadscrews:

Here’s a video from a month ago talking about the wiring that I’d started. Wow that seems so long ago:

Here are some pictures I took while wiring back then:

Then I had weeks worth of round-the-clock work on work stuff, so I couldn’t touch my RepRap for just about a month. But then this week I was on vacation with my family, and snuck in some nights and a few daytime hours of RepRap work. In a previous post nuttzy had suggested that I bring the RepRap out into the pool with me – I did almost that, by bringing it upstairs to work on.

More pictures..

One of the apps I have on my iPhone is a small app that makes it easy to take 3D pictures – you take a left and a right shot, line them up, and it’ll make either a parallel or crosseyed version for you (although sometimes it seems like it’s mixing those up, so I go with whatever works best). Here were two of those that I couldn’t resist taking.. It works great on an iPhone, not so good on a big screen TV. You want it to be small enough that you can cross your eyes and make the two images overlap then click, then the 3D effect takes place and you can easily make out depth. The downside to the first one is the fact that the front-most part is out of focus, which kills the whole 3D effect if you try to focus on it (which is a downside in any 3D pictures/movies).

I can’t get WordPress to not scale these images to be bigger, and scaling ruins the effect, so I’ll provide links to them.

3D-image-1

3D-image-2

The next thing I did was scratch an itch that had been driving me crazy ever since I got the Z-axis installed – I made feet for my Mendel. I also cut out the removable top MDF sheet to place on top of the bed, so that after a print I can just remove that and take the pieces off without reaching around inside the Mendel.

Another thing that had been bothering me was my power connection. Ultimately I’ll get around to obtaining a 12V power brick and connect that to an XLR connector for power, but I’ve been busy for the past month or so, so for now I have an ATX power supply. I’d been connecting two wires from the ATX power supply into the chocolate block on the bottom, but got sick of that, and figured what the hell – I’ll buy a 2nd XLR connector for when I eventually get an old laptop 12V brick, and free the current one up for me to wire it for use with the ATX power supply. However I didn’t want to wed myself to any particular power supply, since they often die, so I needed a molex connector.

I couldn’t bear to cut one off of any of the countless computers/accessories in my house, and I actually started looking at mouser.com for raw parts. Crazy. Instead, Y-adapters for 4-pin molex power connectors are like a buck. I had one in the other room, but again thought of the many times I use it. I went online, bought 3 more at around a buck a piece (they’ll arrive later in the week), and that freed me up to butcher that cable. Here’s the very nice result.

By the way, I LOVE the feel of an XLR connector – the locking feature is nice, and it’s just a very satisfying click. They’re more prevalent in Europe, from what I hear (at least for power) – I’ve never seen one used for power here in the US.

Next, I had the X-axis built up again to the point where it was moving (after having mostly fixed my Z-axis problems, and temporarily disabling my X-axis in the process). As for the details on this next video, I don’t think I was actually using the home feature at this point. I probably moved X, Y, and Z to some non-zero coordinate, then told them all to go to 0. I don’t think that at that point my Y opto flag was working, and Z didn’t even finish during the video, but I was still happy about it:

Next, on to the extruder. I decided to use a purchased 5mm nozzle, but make my own Mendel-sized barrel. In fact, I made it 4mm shorter so that the total length of the barrel and nozzle combined would be the same as the standard Mendel barrel. There was less space for the nichrome heater, but that’s good – I want to keep that heating zone short anyway.

Here I show why I’m building an entirely new heater barrel even though it was one of the first things I’d completed, and showing the old and new one side by side:

So I used that new barrel, purchased nozzle, and purchased PTFE insulator to build the heater assembly. I wrapped nichrome wire around it, wrapped that in Kapton tape, attached my thermistor, wrapped that in Kapton tape, and taped up the wires. Then I took it upstairs to test the thermistor:

I’ve noticed that since I’m so close to being done, the idea of printing SOON has raised the stakes of everything I do. So quite often I’m filming video before doing something, realizing that that might be the video filmed before a moment of tragedy or triumph. Here was one such pre-event video, about the simple task of cutting notches in my purchased PTFE insulator (I’ve made at least 9 on my own, but during my last makerbot.com purchase I threw in one so I’d have a perfectly centered, professionally machined one in a pinch).

And the follow-up result video:

(No, I still don’t have a lathe).

So now I was all ready for another task I’ve been dreading – gluing my PTFE insulator into my Mendel extruder piece. I’ve been dreading that because with the Makerbot I went through at least 5 or 6 PTFE insulators, and this one will be permanently welded to my pristine Mendel extruder piece (which I can’t print any more of, not having a working printer).

As with many of these worry-about-it tasks, there wasn’t much to worry about (at least until the PTFE insulator dies someday, but hopefully that will be after I print out a better extruder piece).

My JB-Weld experience:

JB Weld works by mixing two agents. The first is this black goop:

then you mix it with this (which I put right on top of it in this pic):

Here’s what it’s like when you mix it:

Here was the result before drying:

The next day:

So then, getting really close, I hit a huge roadblock. While others get to use new cool geared extruders like Wade’s Geared Nema17 Extruder or Adrian’s, I’m stuck with the RP parts I have, and that means I’m using the standard Mendel Extruder piece for now (at least until I can print a new one). That means the extruder shaft needs to directly push the plastic against a bearing, and a bare smooth extruder shaft won’t do anything but slip. I’d previously purchased this S10T08M012A0505 small gear wheel to put on the shaft, as suggested under “Adding a small gear wheel” here.

As soon as I went to put it on, though, I realized it wouldn’t fit inside the Mendel Extruder part:

Ignoring that problem for a while, I continued on with tasks I still had to tackle. I built a small stripboard with two 4-way connectors, as was suggested in the RepRap Wiring video – one set of four is for the extruder stepper motor, and the other is for the heater and thermistor connections. I built an 8-way ribbon cable with two 4-way connectors to mate with that. Here’s it all put together:

Then I got the final Z opto flag remade in tin and working great (somewhere before this I’d remade the X and Y opto flags in tin as well). The original Coke-can ones I’d made were just too flimsy – a slight breeze would knock them out of alignment. These new ones were made from a tin can of mandarin oranges (thanks Emily!). I also had to replace the X opto endstop board with a spare I’d made, because it stopped working for some reason (I’m using polarized connectors, so it wasn’t the polarity).

Finally I wanted to see my extruder actually extrude (which I originally envisioned I’d do waaaaay before assembling any of the Mendel itself!). I rested the extruder on the top of the frame, hooked it up, and did the test (pushing plastic in by hand). Despite what the first video says, I went with 170 degrees C (who knows what temperature it really was – I haven’t done any thermistor calibration or anything). I was using UltiMachine 4042D PLA.
Two part video:

Ok, so that left one remaining problem.. Getting the extruder motor to be able to grip the plastic to push it in by itself. Not being able to use the gear wheel, I decided I’d try cutting splines in the shaft, as described under the “Getting your stepper to put splines on its own shaft” section of the Pinch Wheel Variations page.

I built this rig to do the trick (from the above instructions):

Then here I describe and use the rig:

Did I mention I was close?

Laurie and I were up pretty late, as I told her I was so close that I needed help bringing stuff upstairs.. I brought the RepRap, and she brought the lazy susan with PLA on it. As I untied the twist ties around the PLA, I remembered when I’d tied the PLA up previously – it was when I had to return the Makerbot; that was a sad moment, this was happy. We set our expectations low (rightly so), hoping just to have it extrude. We then had the X-axis start to fail (aaaggghh!!!), but Laurie figured it out (she’s a genius!).

And there ya go.. That’s all I have. I started typing this up Saturday night, ended up typing it through Sunday night. Actual prints probably not coming until next weekend sometime.

(and congratulations to anyone reading this far.. Did you actually watch all of those videos?)

Thanks go to Tom Royer for the continued use of his corded Dremel (vs my cordless one), and to Reed P. for his Dremel extension (which I’m returning tomorrow as I now have my own). While I’m at it, thanks to P. Newman at work for helping me with various mechanical issues that I couldn’t figure out (like how to remove a stubborn set screw which was driving me crazy, among other things). Thanks to Chris for giving me someone to talk to in person that’s reading as many of the online reprap blogs as me (your parts are coming soon I hope!). Thanks to Laurie, Emily, Alicia, Cara, and David for giving me a day or two of our vacation to do this latest push, and for being the best support in the world.

Oh, and again, thanks to you for reading this far. Seriously, who made it this far?

I wake up to Laurie exclaiming “Wake up! Look outside the window!!!”. There, practically filling the entire sky, is a huge yellow hot air balloon!!!

The morning started with this picture. Can you see it?

I ran outside..

So then I ran back inside, grabbed my Segway keys, hopped on the Segway, and tore down the street.

It's got a bear on it! Thank you digital zoom.

I went around the corner (I’d now gone from Brookside Ct to Maple St, and now onto Hampstead), and could just barely see it disappear beyond the trees:

I figured it was completely gone, and that I’d made a mistake by not staying on Maple, but I continued up Hampstead St then took a left onto Howe. I rode for a while without seeing anything..

And then..

It landed!!

...

....

.....

......

It's down

The basket

Deflating

Of course, as always, I can’t say no to someone who’s curious about the Segway:

We started counting how many types of vehicles were within a fifty foot radius.. That included this wheelbarrow:

Putting the balloon in a big wheelbarrow

It was interesting to see what was involved in packing away a huge hot air balloon. My Segway has a bit less maintenance.. but then again, it can’t fly.

Lots of work packing up the basket..

I asked if they had a brochure and they handed me one:

That's the balloon, there on the brochure!

What they end up doing is lifting the basket on a lift and just tying it down lifted.

Ready to drive away

So here’s the summary video describing my crazy experience:

The balloon left from Walmart in Salem, NH and arrived on Shearson Drive in Methuen. Here’s a map to show some idea of the distance it traveled:

View Balloon trip – 2010/06/05 in a larger map

(or click here to see those three places in Google Earth).

It went at least 3.65 miles before reaching our house, and then another .92 miles after that.

Cool!

And sorry that this has almost nothing to do with RepRap. It does deal with heat, and this is my vacation week, so maybe I’ll get an actual RepRap post out soon.

The boards I thought were bad were suffering from not getting 12V or GND connections on both sides of the board. Contacts would be made somewhere, but not everywhere. Enough was connected that the green power LED would light up, but no power would make it to the stepper motors.

I desoldered the screw terminals on both fully-modified boards and fixed them. To make sure I was getting contact on both sides of the board I figured I’d play it safe – I took one of the metal contacts I’d ripped out of an RJ45 jack and soldered it in along with the screw connector. First, I soldered it on the top:

Then I bent it beneath and cut it to length:

Video:

I soldered the screw connector on after that and everything worked fine!

I mounted the boards on the Mendel again, and stopped for dinner.

One point worth mentioning for anyone following down this path.. The way I was determining if a board was working was by connecting it via ribbon cable to the motherboard, connecting power, and then looking for lit LEDs next to the ABCD stepper motor connectors (such as the incredibly bright red LED in the first video above). However, I later discovered that this method only works when connected to the X or Y stepper driver port on the motherboard. The Z stepper driver board won’t light up those LEDs, even though the board is fine. (I went through a quick discouraging moment where I thought I had a bad cable or Z port on the motherboard). Actually using the RepRap host to move the motor, however, works.

Once I realized this, I remembered reading that the Z motor is only enabled when it’s needed (since it’s used far less during a print). I think that even might be configurable in the firmware, if memory serves. That’s also probably the enable line that everyone was talking about before (either in the comments in the last post, or in various threads on the Mendel forum).

Now my biggest obstacle is the summer. Trying to get our pool usable is eating up daylight, and once it’s open, that will eat up more daylight. Maybe I’ll be building by night.

p.s. Just because this post is so short, here’s a quick video showing the acceleration that RepRapHost (or actually probably the FiveG firmware) does during simple move commands:

Ok well the good news is, my 16 day hiatus is over, and I can try addressing my stepper driver board problem.

The bad news is, one of the two replacement boards that I purchased to address the two bad stepper boards is now bad too! I’m afraid to touch the last one.

I was grounding myself the whole time, so I don’t believe it was a static problem. I used a 15-watt soldering iron. I had the board grasped by the corner of the board, in a vice, and made sure it didn’t come into contact with any of the components or circuit lines. The page describing the necessary modifications is here.

First (before any modifications, and before apparently breaking one) I tested both replacement boards (unmodified) by connecting them (one at a time) via ribbon cable to the Y-axis port on my motherboard, which was connected to the computer. I connected one of the makerbot.com Kysan stepper motors (with the clip still on it, so the motor wiring was right), to the stepper driver controller board. I connected the molex 4-pin power connector from a PC power supply to the stepper driver board.

I turned it on (this worked for each of the two boards), saw not only the green power light but bright red and green lights next to the stepper motor connections. Those bright red lights will be on even if all you have connected is power and the motherboard connection, the stepper motor cables don’t need to be connected.

Here’s a picture I took later of what it looks like when it works, on an unmodified stepper driver board.. The ribbon cable is going to the motherboard, and on the left I’m holding the red and blue wire (red=12V, blue=gnd) coming from an ATX power supply’s yellow and black cables (multitester says it’s the right polarity and it’s 12V):

When the stepper motor is connected on a board that lights up like this, it can be controlled via the RepRap host software on the XYZ panel. I got motion from both boards before modifying the first of the two replacement boards (which is now not working).

I only made ONE modification, then immediately tested it, and it was already dead (the green power light goes on, but none of the lights near the stepper motor connector go on, and if you connect a stepper motor you can’t control it via RepRap host – it’s completely unresponsive). The only change I made was removing the 4-pin molex connector and soldering on a two-way screw connector in its place. Here is a picture of the first of the two replacement boards, apparently broken (note the green power light in the bottom right and its reflection on the RJ45 jack, which is the only lit LED).

I’m extremely irritated/concerned/disheartened.. When I modified the original three boards, one of those worked and two didn’t. Now one of my replacement boards doesn’t work already.

Has anyone else had this happen to them?

I’m open to suggestions. I’m afraid to modify the other replacement board, lest I destroy that one too. I’m seriously confused because I was extremely careful – maybe even 15watts is too hot? (I made sure not to use my 35watt soldering iron). I’ve checked the board and there are no obvious shorts etc.

Aarrgghh!!!

…but I am damned close..

So first off, right last week’s post I determined the cause of my recent motherboard problems – the cheap ATX power supply I’d bought from MakerBot in late October had died after 3 uses. I grabbed one out of an old PC, and everything was working again. I quickly recorded these three short youtube videos demonstrating at least some limited X, Y, and Z axis motion:

X-axis motion!

Y-axis motion!

Sickly almost Z-axis motion

While that was fun to do, and showed me that at least the hardware could move (and that I still have a problem with the Z-axis), that wasn’t the ultimate test of the electronics, because I’d only started doing the electronics modifications required for all of the circuit boards, and they’d have to be retested later. So, I dug into that task, and proceeded to make all of the circuit modifications necessary to all of the boards.

If you do something enough times, eventually you get good at it.

What a strange new skill I’ve aquired – removing RJ45 connectors from circuit boards. I’ll never use that skill again, but I’ve become pretty good at it.

Again, I’ve found it helps to pull the still-soldered-in wires to the front of the plastic RJ45 enclosure (out of their slots), use pliers to break off the black plastic tabs holding it to the circuitboard, grab the RJ45 connector with the pliers and then bend up 45 degrees off the board (on the wires), then down, left/right, etc, then you can get it off first – and desolder the pins later.

Far tougher was the molex power connectors.. The whole bit in the instructions about melting one bit of solder, prying that part of the connector up a bit, letting the solder harden, then moving to the other side really did work.

Here are the three stepper driver boards, with everything removed.. (the one on the left already has its new 3-pin header for the opto-endstop connection, which I used for last week’s post).

So it turns out the 2-way screw connector I obtained for power for the stepper driver boards had 4 pins instead of 2. There’s no harm in that, it just means I have extra (live) pins hanging in front of the board. I decided not to order new ones and wait, but rather press on with these.

In my eagerness to solder something on, despite careful attention to other details, I can’t believe I actually soldered on this screw terminal backwards:

That meant that now once again I had to use that same melt-one-bit-of-solder-then-pry-that-side-up-and-let-the-solder-cool-to-add-tension-then-move-to-the-other-side trick that I’d just learned on something that I just soldered onto the board. Here is the fixed board with the screw terminals facing the right way (the blue silly-putty looking stuff behind it is called Blu-Tack, a silly-putty-like reusable “adhesive” that I’d never heard of before the RepRap project, which I found myself using to hold circuit parts in place before soldering them, which mostly worked well except the putty would get hot).

Here’s the final state of the modified stepper controller board. In the 3rd picture you can see the two live pins hanging over the end of the board, which I’m not too worried about.

The screw terminal I bought for power for the extruder controller board had 2 little plastic pegs on it that also were going to get into my way. I cut those off.

Here’s my modified extruder controller board. On this one basically I replaced the RJ45 jack with a screw terminal and a 2-pin header:

One of the toughest things for me to get off was the ATX power connector on the motherboard. I’d read that I needed to use forceps to reach in and pull out pins as I melted the solder on the other side of the board. The closest I could find to forceps one night while driving home was two different tiny tweezers. Neither could reach the pins well. Then I realized that I didn’t care about the ATX connector at all, so why not just butcher it with my dremel, cutting around the entire side all around, so I could expose the pins more. That worked out well.

Here was the resulting butchered plastic after I successfully removed all of the pins:

With all of the circuit board modifications complete, I mounted them all onto the two pieces of MDF that would hold them.

The bottom MDF also holds the power and USB connectors. I mounted those next.

I then mounted those boards onto the Mendel.

Unfortunately, I’ve now come to realize that it seems that two of my three stepper driver boards aren’t functioning properly. The three videos at the beginning of this post were all done with one stepper driver board being connected to one stepper motor after another. The other two boards won’t cause any motion in a stepper motor at all. Their green power LEDs come on, but that’s it.

That’s left me in a state of debugging. Here are some messy pictures, with wires everywhere, of what my Mendel currently looks like, with the boards mounted and cables running everywhere.

And on THAT note, I’m done with this post, and aside from any remaining RepRap work I may get done today, I’m probably done with progress for the next 16 days or so, as I’ll be otherwise occupied. So close! Certainly way closer than I thought I was a while back. Which statistically probably means I’m not as close as I think this time either. Either way, this is a fun ride!