I just realized that I have some Polymaker Flex filament in my inventory that I've never even tried to print. It might be less slippery than my Makergeeks Flex filament, but I'm sure I'll still need to "chase" any flexible filament through my UMO Bowden tube with some stiff PLA. If the Polyflex doesn't have a slippery surface, it might be a good alternative to Ninjaflex for the wheels. I definitely think I need this Ninjaflexwheel feeder for my UMO but I might make a new mod to my UMO first anyway--just to see how much it helps with flexible filament. I can drill the Bowden tube path much closer to the knurled drive bolt and push the Bowden deeper for less gap. On the other hand, it might not help much, because that path in the UMO feeder is already supporting the filament with a Delrin pressure foot on the back and a square channel in the wood frame on the other three sides, which fit the filament quite well. I even sprayed the wood path with Teflon dry lube, but I think my Maker Flex filament still hangs-up and kinks a little there. I actually have two feeders for my UMO, because UM updated my original (OUMO? ;)) feeder to the Bertho (roller bearing) style shortly after I bought my UMO so UM sent the upgraded feeder with my kit at no charge. I also turned my own hobbed brass bolt in a fixture I made for my lathe. The hobbed brass actually grips a little better than the knurled UM design but, when the hobbed bolt grinds the filament all, the teeth immediately clog and it loses grip. On the other hand, the UM knurled design tends to be self-clearing when it slips. My Maker Flex doesn't tend to clog my hobbed bolt when it slips so I think a hobbed brass bolt works better than the UM knurling. I found this discussion on the UM Google group about the UM2 stepper. Apparently UM shipped it with a 400 step (0.9 degree) motor: https://groups.google.com/forum/#!topic/ultimaker/qCBoH9TX6z4 Joergen's link to an aftermarket replacement still works: https://www.sparkfun.com/products/10846#reviews So it might be a U.S. sourced 400 step alternative to the motor you used, Diego (which is spec'ed as 1.8 degrees / 200 steps). On the other hand, I hope a 400 step motor can be driven by my old UMO hardware, requiring only a Marlin configuration change and re-build perhaps. Factory UM2 parts (like the knurled sleeve that I'll need) are also available here in the U.S.: https://fbrc8.com/search?q=um2+feeder I might also make a UMO adapter plate for this design and use the UMO gearing, which also affords me a manual method of advancing filament via the UMO "big wheel" (large gear). It would be easier to make the mods, if I had a .stp or .igs file, however, which my Geomagic 3D modelling software can read. (It can't read the latest Solidworks format). Lathe-turning a drive shaft that's 5mm on the end to replace the original UMO drive bolt/stud is not problem for me. The 5mm end would then drive the UM2 knurled sleeve. Other UMO modders might like to retain the UMO feeder stepper too.

Hey Calinb, So yes, the first gap from down up (knurled sleeve to the wheels) is failproof, never had a problem there in 1000+ hours of printing. The upper one needs improvements like I said, I just lack the time to do it atm. I couldn't find your message, sorry, but you can mail me at mrdmolina at gmail dot com. Cheers, Diego

Thanks for your prompt reply and information, Diego. Also thanks for the offer of the Ninjaflex wheels. I'd like to offer you something in trade for them, however. They will save me the trouble of a tricky print with my UMO feeder! Yes--I noticed that gap you filled with a small piece of Bowden tube and wondered about it. I also pondered the gap between the knurled sleeve and the Ninjaflex wheels. I guess the gap between these two feeder "stages" is of no concern, because the Ninjaflex wheels pull the filament away from the knurled sleeve and keep it from kinking in the gap. I sent you an email via the Youmagine site. Please let me know if that email doesn't work for you. Best, -Cal

Calinb, I´ve built another UM2, and I´ve used these motors: https://www.aliexpress.com/item/10-PCS-Nema-17-Wantai-Stepper-Motor-70OZ-IN-2-5A-42BYGHW811-CNC-Cutting-Foam-Mill/332158423.html?spm=a2g0s.9042311.0.0.KoSINo You´re right, the bearing needed is a 688-2RS (the one you indicated). I´ll correct the description above. I never use retraction when printing with flexible filaments, have not gotten any consistency with retraction, doesn´t matter the feeder or filament. This extruder works well for flexible filaments, but can be modified to be excellent with a little piece of bowden tube (aprox. 8mm of it) from where the filament exits the gears and enters the connection to the bowden tube. I needed to print a 24 hours job with ninjaflex and the filament kept running out thru this space, and now with the bowden tube I make long prints with ninjaflex consistently. I have spare ninjaflex wheels to spare, maybe we can arrange that I send you some, idk. Let me know how it turns out. All the best, Diego

I'd like to install this feeder on my UMO. I assume that this feeder works well for feeding flexible filament. I think I can print the flex gears in Ninjaflex on my UMO, but I'll have to print them by "chasing" the Ninjaflex down my Bowden tube with some nice and stiff PLA (and no retraction, of course). According to Cura,, a single flex gear requires only 16 cm of filament. My Bowden tube is much longer than 16 cm so it should work. (At least this method has worked for me with small Maker Flex (TPE) printed parts, but Maker Flex parts have a too much of a slippery surface to work well for a drive gear, I think). I will need to buy a UM2 stepper motor, because I've heard the UMO motor does not have sufficient step resolution for a direct drive feeder setup. I'd like to find a stepper motor with a longer shaft so I can mount a hand wheel on the end of it too. I will also need to buy a UM2 feed pressure bearing and knurled sleeve and setscrew. I think the spring from my UMO will work. The parts list here calls for a 8x5x3mm Metal Bearing but 8x5x3mm doesn't make sense. Can someone please confirm that the bearing is actually 8x16x5mm? According to the UM2 BOM on GItHub,, it is a 1021_Ball_Bearing_688-2RS: https://github.com/Ultimaker/Ultimaker2 and it is 8x16x5mm https://github.com/Ultimaker/Ultimaker2/blob/master/1021_Ball_Bearing_688-2RS_(x1)/B1021-Z1P-A.PDF A 8x16x5mm bearing should fit the bearing yoke and arm parts here. Thanks for the help and I'll upload any additional parts that I design for a UMO application.

Hi, Sure, I can run an export to another file format, do you have any preferences? -- D Molina dmolrub@fastmail.fm Links: 1. http://www.youmagine.com/designs/ninjaflex-geared-ultimaker-2-feeder#activity--comment-create--8661

Hi, Could you please share the parts in an other format than STL? I want to integrate an gearbox and printed push-fittings and to the parts that I have laying around. Converting STL just generated an headache for the computer and thus myself.

best feeder I ever had. Thank you

Hoi, Is it possible to have the ipt, stl or igs files? Gr, Martrin

@dmols - Nevermind (prob printing in ABS would be fine) I'll adjust gears' inner diameter using sketchup. I think we can delete all the spammy comments below. In essence my problem is that inner diameter of gears is too big and it causes a bit of backlash. People be aware of that. Also I used Ultimaker Flex-PLA which does not have much grip (like NinjaFlex) so I advise others to do not even try if You do not have soft and grippy filament.

@Talon - I didn´t design the gears, that was inherited from another design (the link is at the top of this page), I made no mods to it, so can´t help you out on this one. Maybe your printer is not printing to spec? Or you could try printing in ABS? The moment you start to resize gears you need to mess with the whole design, which is doable but undesirable if you don´t wanna spend much time around it.

Sorry for spamming this one, but I tried assembling resized feeder onto my UM2 and there is too much space between motor shaft gear and other gear. @dmols could You please post gears' source files, so I (and maybe others) could resize their IDs.

@dmols - I printed everything on 0.985 scale in PLA and now everything fits about right. Motor mounting is a bit difficult but I guess I'll be fine.

@talon - I tried printing the gears with ABS, the problem was it expands near the bottom and the gears become uneven. Lately I've been using Carbon Fiber PLA, printing really slow, like 10 mm/s, and they print really nice, flawless I'd say.

@dmols. Problem is that the PLA gears Inner Diameter is a bit too big (8.2 instead of 8). So there is some free space around bearings, which (when combined 3 gears) allows backlash. Thanks for advice about PTFE lubricants (btw. PTFE = Teflon) Do you print gears with ABS or Nylon?

@Talon - I haven't tried PLA, but it might be that the size got a little smaller somehow. You shouldn't get backlash between the gears when you switch from going forward to backwards, because than you'd have problems with the retraction... Maybe before you reprint you can put everything together and test, no harm there I think... Anyway, from what you describe you might need to reprint the gears, print it slowly to get a good result. I use dry lubricants to get things moving smoothly (PTFE or Teflon works the same).

@dmols - I printed in PLA (not the best quality, but pretty good one). I assembled it on spare motor - everything fits tight, except there is some freedom with bearings (as I've mentioned 8mm bearing in 8.1-8.2 holes). As a result there is some small wobbling (back and forth) with gears (because of larger ID) , I'm not really sure if it will be a problem while printing. Did You oil gears (light mineral oil or synthetic grease?) to reduce friction or no?

@Talon: What material have you printed the gears with? Everything should fit perfectly, without any play when mounted completely. Put all parts together and check please. @ChrissyP: It seems that the power needs to be balanced, otherwise you end up chewing material or clogging the nozzle, so the present design seems to avoid those issues nicely. Maybe a design with a planetary gearbox would work best with more power, be my guest to try! ;)

The groove I made is in the original gear!

I made no changes and the print is working well. Once I would love to have more power, because sometimes the stepper is rewinding.... Uuupps I forgot. I have made a small groove. It works better when I print smooth materials.

Hi there, I have printed whole assembly, but for gears, I get 8.1-8.25 ID, when not completely assembled it feels that it has some free movement. However the body seems to fit spare motor nicely. Should I reprint my gears with -1% scale or should I just assemble it and hope that it will be nice and snug.

Sorry double posted, what should I say... Tablett :-)

Here we go https://www.youmagine.com/designs/ninjaflex-geared-ultimaker-2-feeder-xlarge Enjoy.

Hi dintid. I'm like you. I have some 3x10x4 bearing with me and I have enlarged the inner of the gear and holes on the body and cover. Easy fix with Blender. Printed the parts and works a charm. I will try to post them.

Managed to get the ninja-flex parts on :) I'll post a remix once I get everything in working order with the slightly larger bearings. Having issues with the lid/cover not being completely level though, but I'll figure something out. Thanks for the work again :)

dmols. I'll working on conversion while waiting the 2-3 weeks to get the cheap bearings. The cost like £10 in the EU + freight :) Need to enlarge the holes a bit in any case to make them 0,2 larger :) making them ,2 og 2,2 isn't much difference. Do you have any tricks to get the Ninja flex parts over the big gears (the right end of course).. am afraid of breaking something.

Hey, so about the bearing, the ones you got won't fit. There is little room for increasing the gears inside diameter, so to make them work you would have to resize the gears, wheels, body, everything. I wouldn't go that way for some cheap bearings you can get easily, the tuning part is the most troublesome work of designing something like this. The 2 part yoke was inherited from the previous work, I didn´t touch them. Again, if you make just one part you will have to adjust the arm, but why fix what isn't broken? :)

Hello. hehe, by the ok'ish I meant they were a bit tight, but it is really not by much, and it Works fine when it comes to gripping and realeasing the bowden tube (using 6,4mm from E3D). Any reason why you use a 2-part yoke instead of just some middle-piece to fit into the bearing (the baring for the bearing arm - I assume it is where the 2-part yoke goes?)?

Hehe, yes, i meant the Ok'ish as the holes was a bit tight, but they seem to work. I havn't recieved my Ninja-flex parts yet, so havn't been able to test it. Just realized my I don't have any 3,8,4 bearings but only 3,10,4 bearings, so I'll see if I can make them fit - I'll get back to you, once I've tried it out.

Hello dintid, Glad you could test it. I'd like to clarify the ok'ish (lol) part of the fitting: you mean an increase in the diameter of the hole for the clamp would make for a better fit? It is indeed a shortened down version as you say, but I remodeled it from scratch after my messed up STL editing started to give printing problems. So on this one the topology is clean :)

Thanks dmols. I just tested the Bowden version. I even mirrored the bowden on the "output" end to the "input" end, as I like to have some bowden tubing as an inlet. Seems to fit ok'ish. The bowden clamp-holes seems a bit tight compared to "Alternate um2 feeder v2", but the tube is getting grabbed and hold. I'll make a version where I can feed the bowden tube right into the respective gears in either en - just a wideing of the holes really :) Am I right that your "body" is simply just a shortened down version of the body from "Belt Driven Ultimaker 2 Extruder"? Asking as it seems identical but seems like it has been edited directly in STL format (I do that a lot myself, but it can end up with some corarser corners etc)?

Ok, bowden tube version available! ;) filename: 3_body_bowden.stl

Hey dintid, will get around to make the one with bowden clamp as soon as I can, check back in a couple of days! I´d definety recommend 100% infill, you need everything included as hard as you can! I think you can get a fine working version with ABS, in my experience I got the gears in carbon fiber PLA, the body I have versions in both materials, they both work fine.

I would love to have a model for use with stock um bowden clamp as well :) Do you recommend printing it in ABS or definently not ABS (due to particles) or doesn't matter? 100% infill or just 20, or?.. seems youmagine objects always recommend very low infill like 10-20, but it just seems wrong to me ;)