Rich's Bowden Geared Extruder for 3mm filament

by Woodsmoke, published

Rich's Bowden Geared Extruder for 3mm filament by Woodsmoke Mar 26, 2013
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This is a geared extruder for Rostock, or any other RepRap printer. It is flatteringly identical to RichRap's recent remix. My changes amount to converting the extruder to accept 3mm filament, 1/4" to 6mm Pneumatic fittings and 4 ID - 6 OD mm PTFE tubing.


Assembly: Apply a little acetone or preheat the ABS locally before inserting the pneumatic fittings. This will ensure the snug fit and prevent the fitting from cheesing your ABS part.

Use: Consider using a light lubricating oil spray in the bowden tube if you are having trouble with filament friction.

UPDATE 27/03/13: The larger pneumatic fitting creates a smaller collar on the Hotend Mount. I have added another file (v2) that will be stronger as a printed part. 2 more holes need to be drilled out.

UPDATE: 29/03/13: More generous sockets have been added to all three printable parts. The original sockets were very tight indeed. The larger sockets still grip well while also making assembly a lot easier.

Remixed Sketchup files included. Remix on!

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I printed the cold end of this using PLA, but I assume I need ABS for the hot end. Any special fill or shell settings? Will this fit a Mendelmax 2?

Hi Marshall, Did your gears break yet? probably not, but I was messing around with the 2 wall suggestion. Ideally there are 5-6 walls on the gears. The weak point though, is on the small gear. If you use the wrong slicer, or the wrong settings, you will end up with weak teeth on the small gear. These will be the first to give way. What ever settings you select for printing the small gear, the result should be pretty much solid.
You can get away with using PLA for the hot end block too, provided you cool the hotend itself. For example an E3D with 30mm fan. Fill settings are not so important. Arguably you want a lightweight Hot end block to allow for faster printing without artifacts. But there isn't much in it.
There are a couple of different X carriages with the older Mendel Max printers. For example Buback's X carriage. This hotend is compatible with that mounting standard. The best thing to do is measure the distance between the two mounting holes (centre to centre) in some CAD software. Then you can compare with your X carriage before you commit to a print.
Good luck and let me know if you have any other questions.

I looked at the triffidhunter gear, and I ended up doing 2 shells with 90 percent fill. We'll see how they work.

This will work well. Good luck and let me know how it goes.

PS: I'd build a 1.75mm filament extruder if I had the choice. You have my support either way.

Well, I'm rebuilding a mendelmax 2 with a stock 3mm j-head mk V. I dont have another extruder, unless there is a way to mod it....

Don't worry about modifying for now then. But for reference: If you can source 3mmOD/2mmID PTFE tubing easily then the modification is very easy. But it's rarer than 2/4 and 4/6 PTFE tubing. The only source I've found is RobotDigg in Asia. You might have more luck in Maryland USA. The modification is simple: replace the 4/6mm tubing and 1/4' pushfit mentioned in this item description with the 2/4mm tubing and 1/8th' pushfit mentioned in Richrap's original. Then line the two 3mm bore shafts in the extruder block and the 3mm bore shaft in the JHead with the new 2/3mm PTFE tubing. Making sure to cut the new tubing accurately to length, so it sits securely in the JHead, and is held in place by the metal of the pushfit above it. You don't want it sliding up and out of the Jhead as filament is fed in and melted.

How many walls did you use? What fill percentage. I know the gears use like 90 percent fill....

Hi Marshall. Two walls usually suffices. Infill varies between slicers, anything over 50% will serve you admirably. If you'd like to have a more detailed discussion about it I'd be really happy about that. Send me an email 3Distributed at Gmail.

Comments deleted.

I'm interested in using one of these on a Mendelmax 2 with 3mm filament. Can you share what hardware you would use with this for 3mm? Screw sizes? Bearing size? Type of knurled nut (Mk7, Mk8, etc). Thanks!

Same hardware as the original Richrap Geared Bowden Extruder Marshall.

Curious, ??? The 2 holes just on the edge of where the push to connect fitting goes theirs 2 of them +/- 9mm diameter with what looks to be a wire tie holes/pass thru. What were they for? Also I just printed one up with a 1/8 fitting. Since mine was 1/8 not 1/4. Nice part! -S

Hi Woodsmoke,

Wich bearing did you use to push the fillament to the hobbed bolt?

Help would be greatly appreciated!

Best regards,

Thanks for listing the 1/4" PT Male Thread 8mm size for the connectors, I have had a difficult time finding the right size for my set up. Thanks again!

Comments deleted.

How do you connect the pneufit & PFTE tube to the extruder body? It seems to me that they are unable to simply be pressed on, and additional hardware is required. If so, what do I need to connect the pneufit adapter to the extruder body? Thanks!

Could you possibly share your retraction settings for this setup? Thanks!

Thank you soooo much!
I can now order my parts to get an dual head printer!

Would this work with a J-head?

I got these push-fittings:

Now discover that I maybe overpaid a bit on them..

How does the 3mm filament do in your Bowden? I am planning to build my MendelMax 1.5 in the next weeks and give it a vertical X-carriage and a Bowden setup :)

Does anyone have a nice picture of both sides of this extruder assembled?

Thanks for the answer. Do you have a picture of the other side of the completed extruder?

I'm afraid the first one I printed is with another owner.

In that case, I will ask the public!

Nice remix, I've not yet tried 3mm Filament in a bowden extruder, but I may give it a go now, thanks.

Cheers Rich, you did talk about 3mm filament in a recent video so I wasn't too sure what you'd think!