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Gcode parameters and installation process for prusa mini

I just spent half an hour writing a very detailed post, and then your website crashed and I lost everything I wrote. Gonna summarize it best I can remember, but I might miss a few details.

I just got the chameleon I ordered. It looks great, but I'm having a lot of difficulty understanding what I'm supposed to do, and the documentation is spotty at best. I tried following the youtube tutorial but I couldn't really understand it. The camera was so far back I couldn't see what you were doing, and I also wasn't sure what portion of it applied to the mini or not. I instead opted to try to follow along with the Instructions page on this website which worked slightly better.

I printed the switch holder from here https://www.printables.com/model/48846-3d-chameleon-mk2-prusa-mini-mounts and put the switch in place. I printed out this bowden tube connecter https://www.printables.com/model/293870-ptfe-bowden-tube-connector and just attached the chameleon's Y bowden tube right to the end of my printer's tube.

I followed the 'Loading and validation checkout' portion of the instructions without much success. I switched to mode 3 successfully, held for 7 vibrations which made it make noise. Not sure exactly what that was supposed to do. I then tried inserting filament into any of the slots but that didn't work. It just wouldn't accept the filament more than like half a centimeter, much less enough for me to shove it through a few feet of PTFE tubes. Sooooo I'm not sure what to do now.

Additionally, the gcode generator needs some explaining. How do I know whether to use mode 2 or 3? According to 'mk3 theory of operation', I would be in mode 1, loader/unloader mode. Except I don't see any 'mode 1 gcode generator.' So I'm following the Instructions page and using mode 3.

I don't understand some of the input values and how to obtain them. How do I measure the button location in mm? Using the printer's built-in Y-axis movement controls, it consistently hit the button and clicked when I moved it to 151, and then it clicked off when I moved it back to 150. So do I just put 151?

What is 'backout distance in seconds'? I assume that's the value we're getting in step 4, "Time the time it takes to move the filament from the Y adapter to the extruder." What does that mean though? How do I time it, or get it to feed when the motor won't let me put filament through it?

'Extruder to hotend in mm' is pretty straightforward, if hard to measure. I'll just input the value I found online for my printer (43mm, rounding down from 43.4mm) and fiddle with it later if I need to.

In the Instructions, it says '4) Insert filament into slot T0 and press the button.' What is 'the button'? I assume this is different than the switch? I can't see any button other than the switch.

Lastly, in that video of you at the 3d printer con, you mentioned the new firmware automatically measures a lot of stuff by sensing vibrations in the filament line. I assume that's the new firmware that isn't out yet? I just want to make sure it's not available somewhere and I totally missed it lol, would save me a ton of measuring and such.

I know it's a lot of questions, I really did try figuring it out on my own, but hours later I'm just stuck and don't know what to do.

2 comments

2 Comments

Bill

Feb 01

Have you seen Chris' Basement video on this installation. He's doing the Prusa Mini as well. Maybe it'll help. But, looking at your installation so far, it looks like you're doing it mostly correct. The only question I have is that black connector between the Y adapter and the input of the Mini's PTFE... you don't need that and it's just an additional point of failure. Just connect the Y adapter directly to the Mini's PTFE tube. Also, I suggest shortening the PTFE tubes, or at least straightening them out... curved PTFE forces the filament to rub the inside of it as it moves, which increases friction and wear on them. You want short straight tubes for it to be efficient.

As for Mode 2 or 3... you need to use Mode 3 for this installation... in fact, all installations are Mode 3. 7 pulses homes the unit.. just like homing a printer, it moves it to a known postion. When the power is turned off, it has no sensors to indicate what position the selector is in, so this resets it to a known starting position.

As fro the button location, you need to watch Chris' video... he clearly explains it... the switch needs to be position to use the very last mm of travel... 180. Putting it at 150 prevents you from using the rear 30mm of the printer's travel.

The Mk4 won't be available until April at the Rocky Mountain RepRap Fest. The sensors are an additional package that will be available for the unit. Your unit will be upgradable to the Mk4 when it is released... in fact, the Mk3 is already using the Mk4 printed components and core electronics. They will be available to all previous users. Here is Chris' latest video that shows how to load the filament as well... see it here: https://www.youtube.com/watch?v=sq4maecRiSM&t=2s&pp=ygUcY2hyaXMnIGJhc2VtZW50IDNkIGNoYW1lbGVvbg%3D%3D

Lightningtow

Feb 02

Replying to

Thank you for the video link, it was really helpful!

I've got it mostly working, I think the hardware is set up correctly. I'm still hitting a few problems tho.

I followed Chris' video and it was great, but one problem was he said to just yank the PTFE tube out of the mini to attach the Y-piece to, because it slides back in. Maybe that wasn't such a grea idea cause now every time the printer tries to unload something, it just pushes the tube out.

I was able to somewhat fix this by unscrewing the hex screws on the orange piece slightly, pushing the tube in, then screwing the motor back on.

The first problem I had is that at times the filament got caught in the tube when the motor was trying to push it, and I had to jiggle it with my hand. Which is fine for first time loading but would cause a print to fail. I think part of it is that the PTFE tubes are somewhat twisted, but idk how to untwist them more than I already have. It also sometimes seems to get caught up in the Y connector, and idk how to deal with that. I tried slightly loosening one of the screws and it somewhat helped. With both pushes and retractions tho, there will sometimes be pauses for a moment where it's stuck and not moving, and idk what to do. I tried doing it like in Chris' first video, where he put the silver pieces in the connecter, screwed it in, and THEN put the PTFE tubes in. I had done it slightly different, by trying to screw the thing shut while holding four PTFE tubes in place in the silver thing. Which helped a lot, but it's still getting jammed at times.

When we start prints, we're supposed to have all 4 filaments an inch from the Y-connecter, with no filament currently loaded, correct?

The second problem I hit is that some of the directions for the 3d chameleon seem to get flipped in transit. It's not common, but not uncommon either that I go to load 3, and it pushes in 0 instead. I tried flipping around the plugs in the ribbon cable but it made it malfunction even worse. I'm not sure what to do about that. There's a few times where it simultaneously unwinds one color and winds another, which shouldn't be happening afaik.

Yeah I tried it again with my finger and some of the controls are getting flipped. I moved T0. Then I pressed it three clicks, to load up T2. It unloaded T0 while I held the button, as expected. Then I held the button, and instead of loading T2, it started unloading T0 again. I'm not sure what to make of that. And I connected the wires correctly, according to Chris's video.

I tried moving T2. I held for three clicks, and then it controlled T1. Exclusively. I did that five times in a row, so the 'last used' filament definitely should have been T2, but it still only moved T1, for both loading and unloading. I've checked five times that all the tubes and filament are in the right place, and they are. And the wires are correct too. Is it possible there's a bug in the firmware, or the motor got assembled wrong before it was shipped to me? I can't think of any other reason it would be doing that. But it wasn't doing that yesterday, so I really don't get it.

After a lot of testing, best I can tell is, attempting to feed T2, instead retracts T1. Regardless of what filament came last. T1 works as normal when trying to directly control it, as do T0, T1, and T2. After another hour of testing (between this sentence and the previous) I'm realizing that at certain times, it's unwinding at the same time as loading a different filament. Which I don't think is intended behavior? Nothing I've seen suggests that that's supposed to happen, at least. I've also checked that all the cords are completely fully plugged in, and they are. After yet further troubleshooting I've found that at least some of the problem was the un-buffered filament was gripping each other and moving one when the other moved, but I separated them out and it's still happening, albeit slightly less often. I've watched the chameleon directly and it's definitely extruding some filament while retracting others, at the same time. I don't know what to do to troubleshoot further, aside from disassembling the whole motor and putting it back together from scratch. Which just feels like a way to make things worse rather than better lol.

Edited