Improving the UM2 feeder mechanism for flexible filament

[ballanux 0]

Hi!

might this kurled wheel work?

http://www.ebay.at/itm/281102410932?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

and I found a similar stepper

http://www.ebay.at/itm/1-pcs-nema17-stepper-motor-0-9-2-4A-48mm-4leads-4200g-cm-for-3D-printer-CNC-/141055057398?pt=Motoren_Getriebe&hash=item20d7895df6

 

That wheel looks great, but I was checking the dimensions and I think the diameter of the UM2 feeder wheel should be 8mm and that one is 7mm. Could anyone confirm this?

The feeder could be modified to use a 7mm wheel but it also should be taken into account in the firmware.

 

[Daid 304]

I'd like to see a design modification with a release button that holds the ball bearing away from the knurled sleeve so you can shove filament in or out with the other hand.

 

We tried that, didn't work very well. The lever is behind the spool and needs a lot of force to open up.

 

[industrialdesigner-uk 0]

Hi folks,

I'm pretty new the art of 3D printing, but i've been working as an Industrial Designer for nearly 25 years.....I think I can see some of the issues here and I have a few thoughts on the subject.

I agree with the idea internal guide feature....looks like a great idea. Should be fairly easy to integrate into the current geometry and certainly worth trying out, however i'm looking at the 'pinch and drive' mechanism and thinking that it would work better if the white plastic tensioner had a built in bearing so that the filament didn't have to overcome the friction on that side of the material as it moved through the drive. I could imagine that the combination of the clamping pressure and the friction together with the softer filament could also be a challenge (?)

I have also had lots of occasions where the filament (normal PLA) has been grinded down by the drive wheel, if there is a build up of pressure at the nozzle end, creating such a deep groove in the filament that it gets grounded and can't be moved through the drive any more...not good.....It therefore got me thinking that if the knurled drive wheel was a larger diameter that would be much less of a problem.

I also have an issue with the detail of how the filament is guided into the drive unit....It isn't really guided at all and I have had a problem where on slightly brittle PLA filament ending up snapping apart at the entrance to the drive unit if the filament reel gets locked up too much as it's unwinding....If there was a nice curved guide feature on the entrance to the drive unit it would help to eliminate damage to the filament.

Just some extra thoughts.....I hope i'm not gate crashing the discussion.

Cheers,

David

 

[IRobertI 516]

"if the white plastic tensioner had a built in bearing"

It might be hard to see in the images posted but it does have a bearing.

 

[industrialdesigner-uk 0]

Ah...ok. I looked more closely and I think I can see it behind the white plastic.

What do you think of my other points?

 

[antonverburg 1]

If you still want to do flexible filament, use Robert's feeder with my mod: https://www.youmagine.com/designs/ultimaker-2-straight-tube-flexible-filament-spool-holder.

It not only fixes the feeder/extruder issues, but also the bowden-tube problems and the orientation of the spool.

[darkdvd 973]

I love this concept ! Great !

[1-prop-head 1]

I too have been trying to print TPU and found that you need a feeder that has as small a gap (zero is ideal) in the pathway as possible. The one I have currently had success was an adaptation of a E3D design but modified to go on the back of the Ultimaker 2 using a 2mm PTFE filament pathway all the way to the extruder hot end. Two postings on Thingiverse cover this one being some of the "1.75 Filament Feeder Adapter Parts" pathway modifications and the other "Minimal gap 1.75 Filament Feeder" that you can print in ABS. The combination of these and adjustments to the fact that TPU needs to be printed slow while depreciating the need for retraction in the print design work for me.