Improving the MMU2 by changing the orange PTFE tube  

Re: Improving the MMU2 by changing the orange PTFE tube

I refuse to use springs from pens on this highly sophisticated 3d printing machine 😀

Sure you will be able to buy "original" ball-pen strings for 2 euro each after this will become part of next iteration 😉

Re: Improving the MMU2 by changing the orange PTFE tube

I got this one on Amazon with prime shipping: https://www.amazon.com/gp/product/B07CBR9M6J/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I bought it from http://a.co/d/cdIlt25 . It says white, but it is translucent enough so that I can see filament through it (even white filament).

Funny, I bought some from a UK vendor on Ebay and then saw this. Ordered this as well. Can't have too much PTFE tubing around. I did every search imaginable on Amazon and this never showed up.

I'm using some 3/32" by 5/32" semi-clear tubing from McMaster.com (part number 52355K54) and it works great. You can see the filament moving back and forth and examine tips on the fly.

Re: Improving the MMU2 by changing the orange PTFE tube

I ordered some extra springs from prusa, but they seem to strong. In general it seems to me that this grinding problem can be solved with the motor driver settings.

Have you tried using springs from ball pens ? As far as I remember, the one invented it use springs from ball pens.

I refuse to use springs from pens on this highly sophisticated 3d printing machine 😀

You realize it's held together with zip-ties, right? 😆

Re: Improving the MMU2 by changing the orange PTFE tube

I bought it from http://a.co/d/cdIlt25 . It says white, but it is translucent enough so that I can see filament through it (even white filament).

+1 to this. it showed up pretty quick as well

on a side note i went from not being able to get a single print to work to 2 prints so far that haven't needed user intervention. benchy (125 tool changes) and chimera (750 tool changes) both done with inland filament and the tips are not as perfect as they should be.

Re: Improving the MMU2 by changing the orange PTFE tube

Springs on the selector? Still trying to wrap my head around how that prevents grinding. Doesn't this make the festo a moving target for the filament to go through? This a "slop in the chain is better" approach?

I definitely understand the larger PTFE. One of the first items to get changed and noticed a large reduction in accumulated friction along the filament path. This brings me to my next question.

Loosening the bondtech gear. I saw results when doing this in regards to grind reduction but it also introduced backlash (of sorts) to retraction. It also means greater risk of layer skipping from loss of grip on the filament. I suppose a there is a sweet spot. Not to tight and not to loose. The reference being looser than you normally would without the MMU2 attached.

Reduce friction / reduce grind / maintain grip on filament / good tip on change

Now we dance the dance!

Re: Improving the MMU2 by changing the orange PTFE tube

Springs on the selector? Still trying to wrap my head around how that prevents grinding. Doesn't this make the festo a moving target for the filament to go through? This a "slop in the chain is better" approach?

The festo only moves when the tip of the filament hits the bondtech gears and stops, allowing excess filament loading to be taken up by the selector springs instead of grinding into the bondtechs. Otherwise it stays in place. It doesn't move in between filament loads. Once the bondtechs start pulling the filament and the MMU2 goes into neutral the festo pops back into place.

Re: Improving the MMU2 by changing the orange PTFE tube

Springs on the selector? Still trying to wrap my head around how that prevents grinding. Doesn't this make the festo a moving target for the filament to go through? This a "slop in the chain is better" approach?

The festo only moves when the tip of the filament hits the bondtech gears and stops, allowing excess filament loading to be taken up by the selector springs instead of grinding into the bondtechs. Otherwise it stays in place. It doesn't move in between filament loads. Once the bondtechs start pulling the filament and the MMU2 goes into neutral the festo pops back into place.

Thank you! Your explanation makes it very clear. Much appreciated.

RE: Improving the MMU2 by changing the orange PTFE tube

I even went wit 3mm ID 4mm OD tubing, It works so much better now!