Printrbot Flexible Filament Direct Drive Extruder

by thirdhorizon Jul 22, 2014
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Great. I tried printing with the flexible stuff on my printrbot with a wooden head but no luck. Do you know if this will work with the arm from http://www.thingiverse.com/thing:281015 ? If I can print most of it, that would be good.

Printrbot Direct-Drive Aluminum Extruder - 3D printed

Had to try a few different designs, but this one is working the best for me so far! Had to do a little post processing to widen the hole and let the bearing move freely, but it works great. I'm even using a Bowden setup for flexibles, which is even more amazing. Thanks for the design! I've printed several things in flex material now.

Can you please upload a file without the support because it keeps coming loose.

Can you add the design file possibly? I'm having issues importing it into solidworks. I want to remove the support so I can 3D print it on my printer with dissolvable support.


Printed this last night in white PLA at 0.2 layer height.

Its a very nice part. The new extruder base is now very close to the hobbed bolt and I cant see the ninjaflex being able to escape around the bolt.

Some observations. It does desperately need modifying to add a groove for the set screw on the hobbed bolt. In the current design the set screw on the hobbed bolt catches and stops the extruder from turning.

The holes on the bottom where it affixes to the powder coated Y arm give a strong fixing once you can get the M3 screws to bite but getting them started is a pain due to varying tollerances of printing precise holes on desktop 3d printers. I would suggest tapering the hole. a slightly wider entrace to allow the screws to gain purchase then tapering to being tighter as they start to bite.

The support material removes very easily but leaves the small dots at the top of the support material attached to the overhang. This means then the hotend is fitted its sits perhaps .5 lower than it did in the ali extruder meaning the z probe needs moving and quite a bit of relevelling. The design looks like it has space to get a sharp scalpel into the gap to trip them off but certainly on mine and looking at the other prints theres not space to do so meaning removing these dots is very difficult and consequently the hot end sits lower.

Only one other comment. Once I'd removed the 20mm M3 bolt which fixes the sprung extruder arm to the stepper motor I found after screwing it back in it didnt seem to have the same bite and consequently the sprung arm tended to slew forward toward the front of the bot when the spring was tensioned. 20mm seems a bit mean. perhaps I damaged the thread on the bolt or the stepper. Perhaps I've rotated the stepper and the new bolthole isnt as good.To fix the problem i've ordered a new set of 23mm M3 cap head bolts. That extra 3mm should bottom out in the body of the stepper and provide a good solid axle.

I will be interested to see how this pla part will hold up on a long print being so close to the hot end.

IMHO 20mm is just too little thread for a good fixing.

Worked completely, but I had some problems printing the holes correctly. Got one printed from shapeway and now it's just perfect.

This worked great for me - I will post a photo when I get home this evening.

I like that I can just leave the part in and keep printing other filaments.

Nicely done.

What did you use to modify this?

+1 on the request for a model with no support. I've tried printing it several times and the support you included keeps coming loose. I'd like to put in my own.

I was also wondering how it would be mounted to the extruder plate.The base of aluminium extruder has internal threads so that the bolt can screw on directly. In this design a nut will have to be added. do you think there is place to have a nut in that gap ?.

I printed one and I am now using it successfully to print ninjaflex, but it would be helpful if you could incorporate a recessed area for the grub screw on the hobbed gear... mine took quite a bit of modding with a dremel to make it work without sticking.

Any Chance you can upload one without the support material?
I use hips on a dual extruder setup so I prefer to generate my own supports.

What is the best infill % for this?

30% worked well for me.

Works like a charm, fit perfectly. Highly recommended.

how you mount it to extruder plate ?

It's designed as a direct replacement for the base of the Alu extruder, and it mounts exactly the same way. If you have a pre-2014 Simple that has the wood extruder, then I don't know the best way to mount it. I'd suggest searching on printrbottalk.com to find suggestions on how to mount the Alu extruder on a legacy simple.

how you mount it to extruder plate ?