Chemrap

Hey, starting this so that there’s a place to discuss chemical printer stuff outside of the old slack. I’m hoping to get documentation up in the next couple weeks and maybe even get the software polished enough for some testing. Let me know if you’re interested in helping, documentation and software are the big needs right now.

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Found this just now, posting as it could be super useful:

Finally got that stupid $&#$2ing calibration script running. That one obnoxious stumbling point has been holding this back for weeks. But I got it working and I got it working with the architecture I’ve been aiming for, which means that the foundation is set and it’s all downhill from here on the code side.

Now it’s a matter of putting in some more actuators. I’ve got some power transistors on the way to control the pumps, and I think I’m going to stick with the knob goblin design for interfacing with the heating mantle.

Then we close the feedback loop with some sensors, put together some synth instructions, and it’s off to the races!

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WOOOOO updates!

Did some testing this evening and have new findings:

  1. needs better seals than the FEP sheet I was using.

Option 1: the PTFE sheet is thicker, more squishable, and might just work as is.

Option 2: vacuum grease and gear that sucker down.

  1. Hobby servos are utter crap and don’t have the repeatability or torque for the job. Had a couple fail smoke test under load, which was predictably hilarious.

Next stop: cheap steppers. Not those fancy Nema motors, but the classic 28BYJ-48/ULN2003 combo.

  1. This peristaltic pump is useless. Diaphragm pump all the way.

The thing barely made the fluid twitch. On the other hand, this diaphragm pump is handling everything I throw at it, including accidental flooding, so go diaphragms.

  1. This peristaltic pump is worse than useless, because air is unfortunately quite compressible, meaning that the precision advantages of peristaltic pumps are out the window.

Thankfully this cheap diaphragm pump is powerful enough to do the heavy lifting, so I’m thinking that the diaphragm pump and a flow meter should be good for rough measurements, and I can probably rig up a new device for doing precision measurements with a syringe pump.

Stay tuned!