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Have been printing a lot of production with UM2 the last two years. Same products over and over again. Thanks to the removable extruder from 3dSolex.

Only one issue frustrates production regularly: the feeder. It grinds the filament now and then.

Found, printed and tested many alternative feeders. Some are nifty and work well, but do not solve the problems. Also consider using a different wheel https://ultimaker.com/en/community/33367-knurled-feeder-wheel-versus-hubbed-mk8-feeder-wheel-for-filament-drive . Any results with that yet?

But i found out that i'm trying to solve the problem at the wrong end.

The bowden tube gives a lot of friction, mainly because of the curve from the backend to the top. When trying to push through some filament manually (after cleaning), simply straigtening of the bowden tube reduces friction a great lot.

(I also found out that for instance PETG has less friction than PLA in the tube. And also found out that some manufacturers do not really deliver 2.85 mm filament but in fact 3.00 mm or even 3+.)

So, is it a strange idea to move the feeder completely to a position closer to the extruder or more on top in stead of in the back of the UM2? And if so, how?

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Are you still using the old Ultimaker2 feeder? the black one?

In that case I would definitely upgrade.

You could get the UM2+ upgrade, but rather expensive as you already have upgraded to the Olson block (removable nozzles) if I understand you correctly, so ytou don't need most parts.

I guess the most logical upgrade in this case is a bondtech.

http://shop.bondtech.se/ec/extruders/bondtech-qr-30-universal.html

You could also get a Ultimaker2+ feeder, as an alternative, but Ultimaker has been making it overly complicated to buy these, though some re-sellers have them.

There's not much you can do with the bowden length, you need to cover the whole printarea, but I did mount my bondtech a bit higher than the original feeder location, but I mainly did that to improve the entrance angle of the filament.bondtech.thumb.png.97f81d36c66c2d4f3cd89ac60f163087.png

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Thanks for the reply @ultiarjan.

In fact, i use one of your feeder designs. Only flaw in it was, after many hundred meters of filament, that the feeder wore out at the bottom, where the filament goes in. I've printed a lot more with a small piece of metal filling the gap. No problems there. I saw you improved that in your latest design.

The Bond-tech thing does not solve the real problem, it only reduces the effects. It addresses the problem at the wrong place.

The Zero-gravity design is a bit like what i had in mind: a direct feed, but without the weight on the extruder. Nice and also possible without the Bond-tech feeder.

Edited by Guest

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Correction: i use an iRobert feeder: https://www.youmagine.com/designs/alternative-um2-feeder-version-two. Just fixed the flaw by putting in 2 cm of the bowden tube at the bottom. The hole was large enough by now to squeeze it in.

The extruder-top-feeder is in my opinion also makeable with the standard UM2 feeder wheel and stepper motor.

I think the wheel can be mounted directly to the end of the long square pin in a printable feeder construction.

On the rear corner of the UM2 case the stepper motor has a bevel gear driving a similar bevel gear where the square pin slides through.

So the sliding is done at the back end (not on top of the extruder), leaving an even lighter part on top of the extruder. The only haulage is the bevel gear. And no need for adjustments in Cura.

I'll ask some mechanical engineering students here at Stenden to work in this.

Edited by Guest
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I don't think there is a fundamental problem with Bowden, only a little drawback. Two of the very commercially successful printers Ultimaker and BCN Sigma both use Bowden drive.

The problem with drive gear directly attached to stepper motor, like the one you are using, is that the motor heats up and soften the filament making it likely to grind.

Also,  if the spring compression is not strong enough, it's more likely for the filament to slip and grind.

Geared feeder with decent ratio could eliminate the heat transfer as well as increase the drive force of stepper motor. A Bowden feeder with direct gear is too old fashioned.

Dual drive gears increases grip to filament and reduce the chance of grinding, like Bondtech UltiArjan mentioned.

You could also check out the one I recently made with dual drive gears and 3:1 ratio:

http://www.thingiverse.com/thing:2289203

https://www.youmagine.com/designs/b2d-extruder-strong-and-silent-bowden-extruder

7c21a54c8606c0409157c8d13936ae98_preview_featured.jpg

Edited by Guest

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