Attempting to print my first Mendel piece

After printing the K block (see my previous post) with the RepStrap, I immediately went ahead attempting to print my first Mendel part. I ambitiously chose the pinch-wheel-bracket-NEMA17_604-bearing_1off.stl file, which is the green part of the following picture:

The green part is what I need to print

The green part is what I need to print

I’ve had varying amounts of success and failure. I have several aborted attempts. Since these were aborted, most of these are just the bottom part of the above piece:

You leave the thing alone for one minute...

Multiple levels of failure

Almost good enough!

This was a very fast print, but it almost wrecked the extruder

The bottom of one of the failures before clearing away the raft

The one on the right is closest. I took a spare ruined PTFE rod and stuck it in the piece on the left (and then fed a piece of ABS filament through it) for illustration purposes.

So, the above one on the right is the closest I’ve come to a functional piece. Worst case, I’d drill through the top, sand off the rough parts, and make it work, but it’d feel better to print it correctly. Clearly I need to do some kind of configuration for this device that I haven’t done (I thought we’d calibrated it but I’ll try again).


5 Responses to “Attempting to print my first Mendel piece”

  1. Mike Allen says:

    Can you recycle the bad parts, or are you doing your bit for the environment by creating a large carbon-sink somewhere? He he he…

    In any case, you’ve now reached the quality required to supply parts to GM…

    • jkeegan says:

      Hehehe.. I’ll be sure to print out a new axle and sell it on eBay.

      Much thought and experimentation has been put into the recycling effort. People save their discards for the day when they can throw them all in a some recycler and create new filament.

      And there’s always PLA, a biodegradable plastic, if you care about the environment but don’t care about getting extra printing material.

  2. Tonok says:

    Try printing the part on it’s flat side instead of vertical. There is no overhangs that way so the quality for that part will improve. You can rotate the part in CAD using Blender or AoI.

    It also looks like you are skipping a few steps here and there. In that case you should turn up the current slightly (using trimpot) on the stepper drivers until the problem goes away.

    • jkeegan says:

      I thought of that (flat vs vertical), but the bottom of the part, which has a cylindrical hole for the PTFE insulator, would have overhang if I printed it on its side. That seems like a far more difficult part than the rest, given the amount of overhang (but I might be wrong).. In fact, the part with the overhang when printing vertical (the recessed area for the stepper motor pulley and bearing) printed fine – the problem was that near the top the extruder must have hit the piece, moving it a bit, and then it printed the last bit of the top a bit more towards the front of the piece than where it should have. It causes problems with the top bolts from the stepper motor, and a problem with the filament hole at the top not passing all the way through.

      I totally forgot about adjusting the trimpots – I’d read that too. Gotta go in and calibrate the whole thing. I’ll try that tonight, if I get some time downstairs.

      • jkeegan says:

        Going through old comments to see what fell through the cracks. I just wanted to take back everything I said in that reply; you were 100% right, the best way to print the Mendel extruder piece is on its back. I finally realized that in this later blog post on the last version of this I printed with PLA.

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