Details on new feeder?

[donmilne 2]

Hi. I've been distracted by other projects for several months and I return to find the new UM2+ offering, with upgrade kit coming soon.

I'm intrigued by the geared feeder, but having searched I can't find any better description than an exterior picture and the name: "geared feeder", and "available soon". Is there perhaps a topic or document that discusses the technical improvements in the new feeder?

I particularly want to know if the new feeder enables a more powerful stepper without chewing up the filament.

[neotko 1,417]

Some info here:

https://ultimaker.com/en/community/18881-geared-feeder-from-um2?page=last#reply-138277

[IRobertI 520]

In addition to that thread I'm pretty sure my pictures here are the most detailed ones at the moment:

http://support.3dverkstan.se/article/64-disassembly-of-the-ultimaker-2-plus-feeder

[donmilne 2]

Hmm. Thanks both. However I don't think either of those qualifies as a technical discussion of the improvements in the new feeder. Somebody thinks this new design solves problems. Which problems?  And what makes this the preferred solution?

As an aside: I see that the new feeder is another closed box. Why not open like Robert's?  (IMHO less prone to clogging up with debris).  Has there been a safety decision that mandates the closed box feeder?

Edited March 3, 2016 by Guest

[meduza 191]

@donmilne: The fact that it is geared and therefore thermally decoupled from the stepper axis is one of the things that makes it able to put more power into the filament without grinding, since the hobbed bolt does not get warm from the stepper like it do on the UM2 (that heat does transfer to the filament which decreases the surface strength = grinding)

I would guess that a closed box design is better safety wise, you can for example not get your finger stuck in there, and since Ultimaker is CE marked and sells a lot to schools a open design might be out of the question (just speculation here).

[donmilne 2]

Heat makes the filament soft at the feeder end?  Although that may be a component, it doesn't really match my intuition. I'd say we get grinding when the rupture force on the small bit of filament in contact with the hobbed wheel is less then the back pressure from the extruder head. I guess that yes, temperature can reduce the former.  When I saw "geared feeder" I had hoped that meant that gearing was being used to drive multiple hobbed wheels and so increase the contact area on the filament, which would also enable a more powerful stepper. So not that then. Oh well, thanks all, but I think I'll wait to see feedback before I jump to replace Robert's feeder that I have on my machine now (and like a lot).

Edited March 4, 2016 by Guest

[neotko 1,417]

If prefer a solution like that the Bondtech feeder seems to be really robust (at 150€+) or just the gears diy (80€).

I think too that a double gear like bondtech it's better, but pricey.

[IRobertI 520]

Heat makes the filament soft at the feeder end?  Although that may be a component, it doesn't really match my intuition.

 

Oh it's definitely an issue. We've had people from warmer climates that have had lots of trouble with the filament being deformed (flattened) by the feeder, especially on retraction heavy prints. With enough deformation the wheel starts loosing grip and starts grinding. As soon as they put a small fan on the back of the feeder the problem went away or was greatly reduced.

[meduza 191]

A stepper motor can easily have a operating temperature of above 60 degrees celsius, and a portion of that heat is going to heat the shaft, so yes it is an issue, especially with PLA and other plastics with a low tg.

I have been running the new feeder since last autumn, and it really is a nice upgrade from the original UM2 feeder.

Edited March 4, 2016 by Guest