Has anyone tried this extruder?

[charles-design 0]

Hi there,

So after having tried different designs of extruder for my UM2 I can't seem to get the reliability I was looking for when purchasing my machine.

I'm convinced the combination of a directly driven extruder with a knurled wheels is a combination that's banned to fail during long prints. Just as a reference the extruder on my reprap mendel which is geared at around 1/30 with a hobbed bolt has never failed after two years of solid use. I'm sure anyone that's used a UM1 will tell how much more reliable the extruder is on that.

So I'm willing to put some money towards a new extruder and I'm looking at http://micron3dp.myshopify.com/collections/all-metal-extruders/products/rostock-delta-extruder-bowden-type, has anyone tried it? Any feedback?

I'm assuming that considering I make a mount to attach it the machine all I'd have to do is calibrate the Steps/mm?

Thanks

Charles

 

[DidierKlein 729]

Never tried the one you linked... what is letting you down with the different feeder designs?

 

[charles-design 0]

Or this one: http://www.reprapdiscount.com/mechanics/64-bulldog-xl-extruder.html

The main problem seems to be the lack of grip between the wheel and filament, when looking at the marks closely it's clear the knurled wheel is constantly slipping on the material.

 

[pm_dude 27]

Have you considered using a flexible shaft extruder?

You can see the tests here with Flex3Drive:

http://umforum.ultimaker.com/index.php?/topic/6987-flexible-shaft-the-best-of-both-worlds/

[pm_dude 27]

What makes you need a direct driven extruder? The UM2 feeder+bowden works great even on long prints. You just need a little change on the feeder

[Labern 773]

Are you still using the stock feeder that came with your machine?

After changing mine to Roberts feeder design and Spool holder I haven't had 1 problem.

20 to 30 hour prints have no issues.

There maybe something else that may also be causing the slippage.

eg. material tangles, deformed teflon insulator etc..

 

[charles-design 0]

@pm_dude I should of been more precise, by directly driven I mean straight off the stepper shaft. I don't think bowden is too much of an issue. On the other hand the flexible shaft idea looks great!

@Labern Yeah I'm currently using roberts extruder and it's not really working out, the knurled wheel is constantly slipping on the the filament. I've tried just about everything without sucess.

 

[pm_dude 27]

what version of the feeder do you have? v6 is working great.

You might just not have nailed the tension right. If its slipping then their is not enough tension. If its grinding then their might be too much tension or you might also have a nozzle issue causing more pressure to be required to extrude properly

 

[randyinla 14]

+1 on Robert's feeder. Have you also tried Robert's spool holder with bearings, as Labern suggested above? The slightest pull on the filament causes the spool to rotate freely. The original spool holder was just plastic rotating on plastic. The friction alone could sometimes cause feeder slippage. Since using both the new feeder AND spool holder, I have not noticed any feeding issues whatsoever.

 

[izzy 33]

I would recomend the Roberts' feeder it's great when swapping materials etc, ive only printed it in PLA but no problems a difinate improvement, ive printed but not added the guide for the flexy material. But I purchased a longer screw for the tensioner and added a small knurled knob to easily adjust the tension, having said that ive not had to adjust it yet. I will be printing a second set if suitable for the dual extruded upgrade for the Um2 later in the year.

I would check the tightness of the screw retaining the knurled nut though, mine wasn't tight and so not effective for material retraction during printing.

I'm going to look at putting a small material straighten below it to straighten out the curl and improve the feeding but not just yet.