Don’t make carriages out of PLA – Four, no, 39 months.. part 17 of ?

Last post, I had us caught up to January 23rd 2013. Let’s keep going. Today is March 18th, 2014. Just over a year behind.

So I was working on the child RepRap that MY RepRap had built, so I could give it to the Museum of Science. During the last post I’d done its first print and the traditional minimug toast. Now I had to get the endstops working.

This was my first Prusa Mendel (IT2) build, so I didn’t know how the endstops would go on (in the original Sells Mendel the optical endstop mounts were all integrated into the build, but on the Prusa Mendel you have a lot of “flexibility”). I decided that I still wanted to use opto-endstops (vs mechanical ones), but that made it more difficult to figure out where the endstop flags should go (and I don’t like the idea of using glue for anything).

For the Z axis, I wanted to design a small opto-flag holder for Z (adapted from the endstop holder for Z). I set up the opto-endstop in a helping hands aligator clip to help measure what the piece should look like, and put the original z-endstop-holder (that I was adapting) on the X axis:

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I measured it, designed what I wanted, and printed it on the Museum of Science’s RepRap (it printed its first enhancement part).

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Here was the resulting part:

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..and here is the new piece on the x-axis where the old original piece I adapted from had been:

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This next video was horribly truncated (probably because my phone ran out of space or battery life) and I usually wouldn’t include it, but it feels a bit historic so I’ll include it for the 24 seconds that it lasts for:

I had more work to do on the opto-flag holder (more on that later), but first I wanted to make a proper filament spool holder. I tried printing 4 of these new-style rod holders (I’d later realize I needed two of these and two of the old style), but then I ran into the new problem that my prints were slanting on X and Y (not individual skips, but full slants for every layer):

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I guess I tried printing something else hoping the problem would go away, because the next picture I have is of that effect getting far far worse:

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It was at this point that I started to suspect that my X-carriage had just melted…

Yup.. Your x-carriage should NOT do this:

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Here was that gear attempt that had failed because the nozzle was lifting up and back left:

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What’s the lesson to be learned here? Don’t make carriages or extruders out of PLA.

Here are some more pictures of the melted carriage:

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I printed a carriage out of ABS on a Makerbot Replicator that I’d borrowed for something else. I wasn’t about to muck with mixing ABS and PLA in a nozzle of my own RepRap (or the Museum of Science’s RepRap) at this point:

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I also printed out an idler:

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…two extruder parts with bottoms designed for the Budaschnozzle, two spare Open-X carriages for me:

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…and the both gears for the extruder:

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Since I was printing ABS extruder and carriage parts, I decided to print some for my brother as well (whose RepRap parts were printed by my printer), since I now knew the PLA carriage I’d given him would melt. 🙂

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Here is what I mailed him:

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Around this time my brother had mailed me a picture of the frame he’d built from the parts I’d given him:

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Jon, if you’re reading this, here’s more motivation for you to finish up and get your printer printing! 😀

Ok back to the Z opto endstop.. At first I mounted the opto endstop board on a standard holder printed out of PLA, which you can see in the upper right-hand corner of this picture:

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I really wanted that to be adjustable though. I found this “Really High accuracy adjustable Z Endstop for Prusa” piece, printed it, and attached the opto-endstop board to it, and mounted it on the RepRap:

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(Actually I mirrored the arm part, since I wanted to mount this on the right side of the machine instead of the left. The mirrored arm piece is now on thingiverse here).

Back to my Z-opto-flag holder, here it is with the tin cut and with tape on it:

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…and here it is installed and ready to swing down in place:

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…and here is the first homing of the Z axis with these parts:

I just uploaded it to thingiverse finally, while writing this post. 🙂

So then I mounted the Budaschnozzle in the new ABS X-carriage. It got stuck at first, and after I managed to remove it I filed the edges of the inside of the circle a bit so it was more easily removable.

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Then I assembled the new ABS extruder:

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Then I realized what I was going to do for an X endflag.. I don’t know if it was by design or chance, but when you’re using a Budaschnozzle mount on the Prusa IT2 x-carriage I was using, a piece of tin right between the plastic part of the Budaschnozzle mount and the extruder is at exactly the right height for an opto endstop board mounted on a standard Prusa IT2 endstop holder.

I modeled them with paper then cut them out of tin after (I say “them” because not only did I put the X endflag beneath the left of the extruder, but I put another shim of metal beneath the right of the extruder so it was evenly balanced).

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Cara was downstairs and help me attach the new X-carriage to the LM8UU bearings:

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..and here she is describing it (again, a truncated video – sorry for missing her saying goodbye):

Cara is a really good RepRap helper.

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Here she is, telling us what the RepRap is doing.

The four new-style clamps turned out great, although as I said before we only needed two of them.

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Then we started two of the old-style clamps for the top (I put two long bolts through diagonal holes, pointing up, and use those as guides to hold the threaded rod that goes inside the spool).

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and my favorite picture of the whole post:

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Well that catches us up to March 8th 2013, leaving me still just barely over a year behind. Clearly I need a combination of blogging more often and to stop using my RepRap. 🙂

See you in the next post.

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