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Pneumatic MMU2 Pulley Body

by Wyzird Oct 24, 2018
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nice, i was planing on doing this. glad i checked thingiverse, saves me doing it myself.

What are the thread dimensions of the pneumatic fittings you used?


Should be the same as the E3D-V6 pass through connector.

I am trying to use PC4-M10 but they are not fitting because the hole in the Pulley body is too large. I probably have to use some glue.

I have the same exact issue; any chance @Wyzird of getting a source file so we could remix with less clearance on the screws? They should be tight but I can push it in or pull it out straight with barely any resistance.

I've used these same fittings on 4 other models with no issue; perhaps the filament you use swells more than the PETG I'm using?

I got the same problem. Somebody is working on a fix with smaler holes?

Hey, sorry for not responding, there was a death in the family. Things have been tough.

I don't have a "source file". I load the stl, modify it, and write the stl back out. Probably not the best way to do things, but it's what I know so far.

I can make one with smaller holes, but without knowing the exact size, it could be tough. What fittings are your using? Do you have calipers you can measure your fitting?

One guy on amazon with the same fitting calculated it as R 1/8".
I measure 9,5 mm outer thread size.

Amazon guy

An M10 thread would be cylindrical and would have a thread pitch of 1.5mm, both are not the case here (see picture). I measured a thread pitch of 28 TPI, so together with the outside diameter one would come to G 1/8 "or to be precise the conical equivalent namely R 1/8".

So, it sounds like just making the hole smaller won't solve the problem... if the thread pitch is also different?

I can try to just make the hole smaller, and sent a small sample to you to try. (Not the full print) That might help?

Can I get a link to where you bought the fittings?

With as many times as I've had to unscrew the 3 screws holding the selector motor in place, I'm strongly considering making it so I can remove the selector in the opposite direction (without removing the stepper motor). What are the chances you'd be willing to update your design (or create a new one) like that? Or possibly share your CAD file for me to hack on?


So, I'm trying to think of how that would even be possible....

The "other side" of the selector needs to be strong enough to hold the selector in place, assuming, for instance,. they enable the cutting blade at some point.

The mounting screw that holds the bracket, as well as the idler tension screw are in the way. So either you make some weird cutout to get around those, or make it one piece. Either way you will still have to fasten that end on somehow, and strongly. I can't see how you could do it with less than 3 screws, so what would you save? And on top of that, you would probably have to add more nuts. I know I removed some that we could re-use, but ugggh.

How about a different question. Why are you taking off the motor so much? The only time I have had to take it off is when I'm changing the idler body for a new test. Maybe that answer will give me a different idea...

And sorry, I have no "cad" files, I actually work directly with the .STL. I know I'm weird, but it's what I'm used to.

Because this thing does very little, other than jam (and make me suicidal), thus far. And it seems like the only way to really solve a jam is to take the selector off the rails. Maybe I'm trying to solve the symptom, rather than the problem, but so far, a month (or more) in, I've managed exactly 1 successful multi-color print. The choreography of retractions, selector moves, etc always seems to fail for me after some number of filament changes.

I hear ya. So, it sounds to me like your tips are too large, and are getting resistance in the PTFE during retraction.

The "ramming sequence" for filament to make the proper tips is bloody magic, and I have no clue how to deal with that.

My first tips to you would be A) Make ABSOLUTELY certain your gears are aligned perfectly. Seriously, it's a real pain in the butt, because of the curved surface of the gears, it's difficult to align these.

Secondly, try tightening the idler springs more, so the gears grip better, to pull the filament stronger.

Oddly, LOOSEN the bondtech gears a bit. It sounds strange, but yea...

Make sure the filament is dry. If it's moist or brittle at all, the MMU can throw fits.

I don't know what filament you are using, but if you have some ABS around, try that. It's more forgiving with the MMU. (It doesn't like to string) Use it to try and get things all working. Once it's working with ABS, then tweak software settings for whatever filament you use, since you know the hardware is set up correctly.

The MMU can be really frustrating, but it does have a lot of potential. They really don't use the filament sensors properly, (or at all) yet. When they get those going, it should get better. (They should have put a bit more effort into this than they did before releasing).

I just ordered some ABS to play with, in hopes that it helps. I thought this Hatchbox PLA was "Prusa tested/approved", but I've been playing to ramming, temperatures, loading and unloading speeds etc, but it in the end, still nothing but jams. Many of them seemingly unrecoverable.

I think the gears are aligned, I have micro-tweaked them several times. I've also experimented with tightening & loosening the bondtech gears in search of skinnier tips.

I know life on the bleeding edge is painful, but this is a whole new level. Thanks for listening to me whine ;)

On a separate note, what software are you using to work directly with STL's?