Extruder recommendations

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Extruder recommendations

Postby geoffs » Mon Sep 01, 2014 10:49 am

I've had some success with the QU-BD extruder after upgrading it with Bart's extrude mods.
Still problems with the hotend jamming after an hour or so (as everyone has said it woudl) so time to upgrade.
I've got a J-Head hotned and I'm looking for receommendations for an extruder to go with it.

I have limited access to a Makebot to print the required parts but only for a couple of hours, once a week. For this reason, I'd prefer a
minimal extruder that I can print in one session (if possible).
Once I get printing reliably, I can print my self an upgrade!
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Re: Extruder recommendations

Postby geoffs » Mon Sep 01, 2014 11:02 pm

I've decided to start with this extruder from Thinginverse.
http://www.thingiverse.com/thing:59855

Basically the same mechanism from Bart's QU-BD modified extruder with a suitable mount for the j-head.
Even if not the best choice, as least it will get me printing iwth the j-head.
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Re: Extruder recommendations

Postby rsm5178 » Tue Sep 02, 2014 1:11 pm

I printed this and have been tinkering with it for the last week or so with a j-head. You will just need to add some washers or get new hardware.The part fits well on the gantry but the extruder is a tiny bit wobbly in the holder. I wrapped the j head with some kapton tape to take out the slop. Don't forget to use your fan or your j head holder will start to soften.

I may eventually get an aluminum holder to print abs because the printed holder will start to soften/get sloppy at high temps. Or I might make something to control the forced air away from the printed abs part.

I found that the extrusion temp, extrusion feed rate, and fan volume needs to be tuned or you will still get jamming.

Rich
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Re: Extruder recommendations

Postby geoffs » Wed Sep 03, 2014 12:33 am

Thanks for the response Rich.
I'm off to the hackerspace today to print one of these. Any configuration info you have on what's worked for you, would be appreciated.
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Re: Extruder recommendations

Postby rsm5178 » Wed Sep 03, 2014 3:59 pm

I'm no professional but I have been doing trial and error with relative success. Someone tell me if I'm wrong, but I've found that configurations are based off of your particular set up. Nozzle size, extrusion temperature, feed rate, and fan speed/volume are big variables I've noticed that affect print quality/reliability.

Side note: Have you had issues with the z axis accelerating too much right after zeroing the axis (using repetier). It sounds like a lot of steps are being missed and ruins the z axis zero.
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Re: Extruder recommendations

Postby fma » Wed Sep 03, 2014 4:45 pm

rsm5178 wrote:Side note: Have you had issues with the z axis accelerating too much right after zeroing the axis (using repetier). It sounds like a lot of steps are being missed and ruins the z axis zero.


+1; this can be source of problems. That's why I always adjust first layer by hand, during brim printing, looking at the extruded filament... This way, I don't have first layer-related issues anymore (I also use 3DLAC, which is amazing).
Frédéric
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Re: Extruder recommendations

Postby geoffs » Thu Sep 04, 2014 5:25 am

Given the other problems I've had, I haven't noticed any z-axis issues ;)
Extruder body is printed - after 3 tries. No.1 lifted off the bed, No 2 (with raft) stopped because extrusion got caught outside the printer.
The other parts for the extruder (Bart's mods), I can salvage from the existing POS.
As soon as I get some muffler cement, I can assemble the hot end.
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Re: Extruder recommendations

Postby fma » Thu Sep 04, 2014 6:13 am

BTW, I juste designed a new extruder, based on a NEMA14 geared motor (http://www.omc-stepperonline.com/gear-r ... p-136.html). This motor has 0.9Nm tork, which is twice the tork of a NEMA17, for the same weigth.

I attached an Openscad screenshot. I printed it, but I still have to order the motor. I designed it especially for Filaflex, which needs a very good filament guiding. Here, I use a PTFE tube, 6/2 (OD=6mm, ID=2mm). The tube is sharpened to a point, so it can be very close to the driving point. The pusher part is also very simple, without spring (I used such pusher on another extruder for months, without any problem); the rotation shaft of the pusher is also pretty crude (the extruder could be printed in 1 part, but would need support, and I don't like support; 2 parts also allow better access by removing the pusher).

extruder_nema14_geared.png

extruder_nema14_geared_ptfe.png

I will soon post it on Thingiverse, but if you want the Openscad file, just ask. The hotend mount is made for a Paoparts hotend (http://www.paoparts.com/fr/extrudeur/90 ... t-3mm.html), but very easy to adapt for other hotends.
Frédéric
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Re: Extruder recommendations

Postby geoffs » Thu Sep 11, 2014 10:41 am

New extruder and J-Head installed and printing!
Still a lot of tuning to do but at least Ican print reliably for over an hour without a jam.

Extruder is http://www.thingiverse.com/thing:59855

Once I have things set up properly, I'll reprint these bits and pieces in the same colour (blue)
Attachments
extruder.JPG
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