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H3 extruder for Ultimaker

by chopmeister Jul 29, 2012
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Do you have the native files or like a step file?

Muy bueno, voy a ver si lo hago y pruebo... Gracias por compartirlo

I made a bracket to fit the H3 extruder sideways:

Sideways H3 Extruder Holder
by Droopas

what should the steps be for the extruder i am using the v3 bolt..

Could this potentially be mounted flat against the backside of the Ultimaker? I dont like how the design of the printer pokes out, so I suppose it would take a mount on the side of the extruder instead of the back.

Hi chopmeister,
Is there any possibility to post or send via mail the design files?. I am designing my own printer, and your extruder fits perfect in my proyecy but I need to redimiension some parts. I use Solidwoorks. Afterwards I would post all my work in the web. thanks very much.

No problem whatsoever, send me your email in a message here, and I'll send you the STEP files.

Hello Chopmeister,

May I ask you the same question as Juanbe?
I also use SolidWorks and like to adjust some parts.
I'll send you my e-mail within a PM if you're willing to share the files.

Kind regards,


I have an question. I just printed bearing axle but it is little smaller than bearing inner diameter. It is ok or it should be tight in?


>There will be a H4 soon

What's the status on the H4?

That's a tough question honestly. My focus now is on the NanoBlock extruder, and a lot of hours went into it. I did do a lot of work on the H4 too, I have 4 mostly working prototypes (each one is completely different) and I'm trying to find the optimal ratio of toughness vs complexity vs usability. I have set the standards for this pretty high, so I don't see it being done anytime soon. The point is, it really has to be better than this one, otherwise it makes no sense to do it. :) Back in march 2013, I thought I would have much more time on my hands for personal projects, but as it turned out, that wasn't really the case.

What is "blue tape"?
(I'm in Germany)

Blue tape is just painters tape, made by 3M, Tesa etc. Everybody mostly uses 3M tape. We call it blue tape because it's.. well.. blue :) You must have seen it around used for covering the build platform if you are printing PLA without a heated bed.

I really like this design, so much so that a built a second one to replace my home printer's extruder as well. However I hit a big snag: long haul prints heat the stepper motor so much that the lower part of the extruder body becomes really soft. Also the drive gear looses grip. How is this problem solved with RepRap machines with extruders made of all printed parts? Are these parts printed in ABS?

I to had the same issue with the step motor warping the part. I will try using a spacer to see how that works, Great print tho.

I must say I never had that problem myself, even on long prints. Could just be your steppers work hotter than mine. In any case I suggest a cork gasket then - it should solve the problem with no fuss. You can easily make it yourself or just order online. ABS is definitely more tolerant towards this issue, but I use only PLA and as I sad, had no problems so far.

I was surprised as the one at work seems to be fine, although they are about a year apart, maybe their amp settings are different. I printed the piece in ABS, it cracked in the middle despite the heated bed set to 110C, but the garage was quite cold. Looks like I'll need to cover the printer for ABS prints to keep it warm. I orderred some cork sheets for the motor mount. I will also isolate the bolts with nylon spacers, should do the trick. But the small gear will have to be ABS, the shaft gets to hot too. I'll also stick some radiators to the stepper...

Can I suggest for H4 that you add a little box at the entrance of the filament as a filament cleaner like this

Filament Cleaner for Series 1 Type A Machines printer
by tilden
Filament Cleaner Case
by icare

The H4 will have an integrated bottom mount for add-ons such as filament cleaners or straighteners or whatever comes to mind. So it will not directly be a part of the extruder, but it will be very easy to add. I think that's a better feature since not all people need or use filament cleaners.

Can I suggest for the H4 (or a H3 revision) that the "Flip Lock" have a small half round added to the back of it, to make it is easier to flip up?

Thanks for the suggestion. The current prototype of the H4 uses a different open/close mechanism, which has the same ease of use as the fliplock, but I'll have that in mind!

Hmm think I could use the Makerbot Mk6 drive gear on this?

Are there any issues using this design with a V3 bolt such as changing my e-steps or using different bearings than the ones laid out in you design .pdf. Great job by the way. I printed out all the parts and they came out beautiful. Just wanted to make sure there were not hiccups that you could think of by using the V3 instead of the V2 bolt as mentioned in the manual.

Well, there could be an issue with the knurled part of the bolt not being correctly centered. This extruder has thicker sides than the stock UM one so you could end up with the bolt being a bit misaligned. I don't actually own a V3 bolt so that's why I never made an official mod for it. But there are parts here which could maybe help if that happens. There was talk about it below and some on the UM forums.

Looks awesome! I am about to print this. I was was just wondering if H4 is just around the corner ?

You're safe with the H3 for now. I am working on the H4 but unfortunately it is far from done, let alone tested, and I have too much work scheduled for the next month or so to be messing with it. I will post updates as soon as I know anything for sure. But considering the time I spent to properly test and adjust the H3, there won't be significant progress at least until somewhere in July.

Thank you! I know, this stuff takes a lot of commitment and time. Keep up the good work!

All parts printed quite nicely, even without heated bed. I just had to wait few week for the follower ball bearing. I really like the design and looks it is working fine.
The only problem is that it hangs a little too low and the motor interferes with the large stock spool when hung on the centre bracket. Good design that the hanger part is removable, I'll just design one that raises the assembly 20mm higher, unless someone else did already.
This one was for my printer at work. Now I will print another one, this time with my newly installed heated bed! I will probably use the modified gears by Gijs to keep the same stock gear ratio...

I didn't really pay any attention to the spool holder since I don't use it. Of all the spools I ever had, only two would fit there anyway. Yes, do try the gears by Gijs, I haven't had time yet but they sound much better than mine.

Thanks for the comment, and good luck with your new extruder :)

Now that I printed few things, your extruder works like a charm.

Great design. I just finished installing it. I modified the gear set however to have the same ratio as the stock gear. http://www.thingiverse.com/thing:80257http://www.thingiverse.com/thi...

H3 gear set with stock ratio (8/49)
by Gijs


I wanted to use pit3k's Bowden clamp ( http://www.thingiverse.com/thing:17027http://www.thingiverse.com/thi... ) with your feeder hack and I made a subtle modification to it. So FYI http://www.thingiverse.com/thing:65838http://www.thingiverse.com/thi...

Bowden Clamp for Ultimaker (Feeder End)
by pit3k
Feeder Clamp with Conical filament driver
by fns720

Hi your extruder is awesome i wondered if it is possible to have the files in any solid format ? i would like to modify it to fit with some of the stuff i have ,i will obviously post the result

Hi!. No problem, just send me your mail in a PM and I'll send them over. I must warn you though that this is the very first thing I ever did in Inventor so the solid files themselves are beyond terrible. I hope you will manage to pull anything useful out of them. I'm also very sorry this design wasn't updated in a long time but I can't seem to find time to mess with it.

What type of spring and what size of spring do I need if you don't know can you send me a link where did you get the spring ;)

i am using the short spring in this kit: http://www.homedepot.com/h_d1/N-5yc1v/R-202045472/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=684838&storeId=10051#.UNvrkW9X0-khttp://www.homedepot.com/h_d1/...

fits well with a couple wide washers and a 60mm m4 bolt(make sure u get wide washers else it'll tear up the plastic) they may also be a little tougher then what i think this was made to use but also the only ones i could source locally. if u use this kit i suggest using my modification mentioned below.

Any chance on getting a modified idler - middle/left/right to support acorn nuts? mine keeps breaking due to the bolt slipping through the nylon nut.

Hi! Sorry for the late reply. Yes that would actually be a great idea. Unfortunately I don't have an acorn nut on hand to measure, but I'll try to get my hands on one and change the parts accordingly. Can't promise when though, I have a chronic lack of free time lately.

I know the feeling, i managed to get it working again with hot glue, and printed off a couple extra of the middle idler part, these are the acorn nuts i have laying around:  


not a perfect measurement, but i don't have any good precision measuring tools.

Anyways it is greatly appreciated and keep busy. ^^

Sorry for not finding the time to do the modification, but I see you've found a better way. :) I use the E steps value of 744.876483763, which works great for me with the UM V2 bolt.

OKI found my problem...By some reason my scale was set to 0.5
The size is better after restore it to 1.0

Are your dimensions in Inch?
My printout is VERY small.

I use my stock Ultimaker V3 bolt with The H3. Didnt need to change anything at all.

Really? According to fluxline's measures of his V3 bolt I would expect some misalignment there, but if you say it's ok, all the better! Maybe there are subtle differences with the location of the hobbed part on the bolt. 

How's the H3 working for you?

He is correct, it does work.  But with my parts, the bearings are a little of on the alignment and causes a slight grinding.  The knurling on the bolt is slightly missed.  If a washer is put between the retaining clip and the bearing then the bearings are aligned, but then too much of the knurling is missed causing slippage.  I will test the inserts that you made for the original bearings.

How is anybodies experiance with replacing the small gear on the motor with the one supplied here?  With my UM rev. 3, I think it is glued to the motor shaft and not easily removed I think.

late reply i know, but it's pressure fitted not glued. a good pull should get it off.

Just finished printing & assembling my new H3 extruder. Thx for your contribution chopmeister! 

Great engineering!

So now for me its testing time.....

Any way to adjust the design to simply use 3 standard 608 bearings?

Well, yes and no. My first design used that configuration but then the filament path is 7 mm wide. That creates problems when pushing filament because it can bend sideways. So then some sort of guides should be used and that complicates the design unnecessarily. Not that it couldnt be solved, but this seemed the better way to go.

This looks really really good!

Do you think it would it work better or worse with a v3 bolt? than a v2 bolt? I have v2 and just received the v3 one.

I suppose it should work with the V3 bolt, although I don't have it so I haven't tested it yet.

Very good stuff! Looks so solid :)

I did a really dirty mockup for a hyena bolt as well, but that's far better!

I've used the hyena bolt a lot lately and what I found is that it has too many teeth. If only they were 2 or 3 less, so they can be a bit bigger it would be perfect. It tends to clog with filament really fast and lose grip, at least in my experience. Since I started using this extruder i switched back to the V2 bolt with excellent results.

Is this in PLA or ABS? Will the motor heat soften the base?

PLA. It will all be in the upcoming instructions, but I have a heatsink and a small fan on the extruder motor. Also a piece of silicon sheet to insulate the strip from the motor.

I meant insulate the PLA not the strip. I've been awake all night. :(

A thin sheet of cork (3to5mm) should be perfect for thermal steppermotor to PLA-extruder-body isolation. It should make active cooling of the stepper optional.

I Forgot:

silicone ~0.2W/(mK) (max ~260C
cork ~0.04W/(mK) (max ~120C°) ... ~5x better

Yes, after all some types of silicone are used as heat sink washers specifically for their ability to pass heat effectively.

Nice, i like this design as i like to swap out my filament often.

What settings did you slice this with?


Hey. I really should have posted this in the instructions, and I will, but for here it is for now:

everything is .2mm layers. Print Small Gear, all three Idler parts, Bearing Holder Bearing Axle and Fliplock with 100% infill (and print the fliplock really slowly, otherwise it'll sag to much). The rest can be printed with the usual 25% infill. I strongly recommend slicing with Cura 12.07 because
all the holes and tolerances are set up to work with that. Note that I always intentionally make the screw holes a bit too tight to get a better grip with the screws. If you mess with filament a lot (me too XD) you shoul also print the UM mount at 100%. That's it.


Im interested as well in the 90' rotation as well, i tend to take my um on excursions. so having something that more rugged and closer to the original shape of the um would be great.

I've seen this as a work in progress on the ultimaker forum a while ago. IIRC this older one used the flexing of the plastic instead of the spring. Was there a problem like too less range of spring/creeping PLA/uncopable increase in quicklock complexity that led you to go for a spiral steel spring instead?

What I like very much on this design is the more vertical alignment of the gears compared to the stock extruder.

Is it (like in the stock extruder) possible to change the filament while printing by simply cutting off the filament and shoving in the next color? In other words is the filament guodi
ng channel of minimal thickness all the way through?

Do you think it is possible/easy/hard to mirror the design and modify the mounting part so that the extruder is rotated 90° to the left? I'd like even less protrusion to the back.

I successfully managed to change the filament while printing a few times now. Note however that the guide channel is not as tight as it could be all the way, and that in order to do it the filament you are pushing in needs to be straight. I started work on a mount which places the extruder on the side of the printer instead of the back so you can actually see what's happening (I spent the last 6 months looking at the back of my UM which really annoys me). Also the mount will have a hinge so you can turn the extruder parallel to the side panel for easier transport.

So changing color on the fly is currently possible, but risky for bigger objects especially when you have low diameter filament coils.

»extruder on the side of the printer«
Does that mean It will not use the "extruder slots" at the back but instead directly mount to the right top wooden frame part in some way? If so you might mount it a little higher such that the precious "moving right fan space" of the carridge (ask if uncle
ae) don't get obsrtucted. But only if mechanical stability doesn't greatly suffer under that decision.

If you add a nice hinge too then two or three lock positions might be necessary, pushing the filament manually shouldn't unlock them.
I know - with lots of functions in few parts and few space it
quickly gets challenging.

Well, for me the changing of filament was effortless the few times I did it, but that's not enough data for me to say, yes it works 100%, I want to see if any problems emerge before I say it can be done for sure. The filament path is 5mm wide due to the idler bearing. there's not much space for the new filament to slip. The only problem is the bowden quick connect. The filament can sometimes hit its lower lip if it is too curved. But the same thing happened to me on the stock extruder many times too. I'm thinking of a chamfered hole beneath the quick connect to guide the filament in even if it's not straight.

About the 'side extruder', yes it will not use the mounting holes. Also the way I imagine it is the extruder being perpendicular to the side panel, so that you can see what's happening and have the spring within easy reach. For travel purposes, it could swing to be parallel to the side. The goal i
s a very tough hinge with options to easily lock the position and remove the extruder if necessary. The mount itself would be permanently attached to the UM frame, instead of the extruder body, as it is now.

Oh, and I love it when it gets challenging. :-D

Perfect plan! Judging from the H3 up till now the hinge will certainly be "just right". I'am looking forward to see the outcome.

Oh - I overlooked that the incoming filamet is still in the way even if the drive is mounted higher. - headscratch - .

To be honest, the spring beats the older one hands down in all aspects. My original purpose when designing was to print successfully with various troublesome filaments I have lying around. This is the first version to manage printing with all of them (some are too soft, some are very twisted so they cause massive friction in the bowden, etc...). Also, I was just thinking yesterday how I could make a mount to let the extruder stick out from the side instead of the back, because I constantly fiddle with it. Expect to see that variant soon. As for the filament change, I will try and post results. :)

Beautiful! Almost makes me want to buy an Ultimaker :)

Thanks, but why almost? hehe :)