MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.

Download Now


Itty Bitty Belted Extruder

by clough42 Jul 9, 2014
Download All Files

Thing Apps Enabled

Please Login to Comment

Could this be made into a Bowden extruder...?

What will it take to fit this to a Prusa i3?

Wondering if a NEMA 14 with 3N.cm torque enough for this extruder?

3N.cm is probably not enough. The ones I use in all of my extruders produce 15N.cm: http://clough42.com/product/nema-14-stepper-motor/

Yesterday i've printed the 80-teeth wheel and the two whashers.
Now i'm confused about the diameters. My M8 hobbed Bolt will not fit into the Wheel and the Hex-Nut (M8) doesn't fit into the Wheel too.
At first I thought it was due to my printer.
But I've tested everything X and Y axes are perpendicular, E-Steps are finely tuned, definitely no overextrusion. I saw that the belt (GT2) fits perfectly on the 80 teeth. This is against a scaling error...

I have no idea of openSCAD but I have looked at the .scad file more closely, and I noticed that the following values for M8 in my opinion, are too small:

motor_shaft = 7.9;
bolt_head_width = 12.77;

I think theoretically this should be 8.00 and 13.00. And practically 8.20 and 13.2 for pressfit?

Any Idea??

Printed with 50% Infill (Honeycomb)
Layer = 0.2mm

There are a couple of variables here. Printers vary significantly in how much they spread and constrict inside holes. Hobbed bolts vary as well. In fact, many hobbed bolts sold as 8mm are actually 5/16 inch bolts instead, which are nearly the same diameter, but actually slightly smaller. And of course the threads are slightly smaller, depending on the thread fit of the bolt.

The size of the hole is designed to be tight, so the screw actually forces threads slightly into the plastic. This helps with concentricity. The nut should also be a tight press fit, deforming the plastic slightly so it stays in when the pulley is removed from the bolt.

I usually thread the nut on flush with the end of the bolt, and then use the bolt to press the nut into the pulley. I then screw the bolt through the pulley to form threads in the plastic that are perfectly timed with the nut before unscrewing the bolt and assembling the extruder properly. If you force the bolt through from the plastic side, it will cut threads that may not be timed properly with the nut.

As with all things, you might need to make minor adjustments for your printer and hobbed bolt.

I was originally going to build the dual flex first but due to the large footprint I decided to go with the Itty Bitty first but even then it was wider than I liked and I wanted to try and use the hot end assembly I was already using on my FT-5 that uses the cooling block and heatsink. I ended up redesigning the body and now it is the same width as the FT-5 stock carriage assembly which is about 56mm. I got it up and running last night and initially set it up with 644.2 for E-steps but it's obviously over extruding and it was too late to go through the calibration steps to figure my exact number. The parts I got from you worked great and I'm amazed at how fast I can push filament through the hot end without skipping a step. I think I could push a Volkswagen sized clog through the hot end with this thing! Once I make a few changes to the body design and I'm happy with it I will post the part with the mounting plate for the FT-5 along with your info for ordering parts to build it. My next step is then a dual for the FT-5 that has one extruder for flexible and one for standard filaments and stay as close to the footprint of the original extruder assembly. There's room to grow on the X axis and height isn't an issue however real estate on the Y axis is limited so I will have to be creative with this one. I definitely like the belt over the gears for the drive and playing with belt length will give me some more room to be creative with the stepper placement.

I printed it out, put it together, and faced a serious problem: I can't seem to find a way to mount the extruder, as the hobbed bolt is sticking WAY out any solution? I have the regular 30mm I3 x carrige

It all depends on the bolt and the carriage of your printer. How long is your bolt overall? Does the toothed portion of the bolt line up with the filament?

It does line up, I ran some tests on it before trying to mount it and extruded filament manually without the hotend connected - worked wonderfully. I believe the bolt is 7cm long, not sure. It's the one on the makerfarm kit

I had the same issue with the MakerFarm bolt on the prototype. I just cut the end off and filed it smooth to make it fit. The stock MakerFarm i3 back plate had a hole that lined up properly on the stock extruder, but is in the wrong place for the Itty Bitty Belted Extruder.

If the bolt you have is really 7cm long, that's pretty long. I thought they were more like 2" (5cm) from the tip to the shoulder of the head.

Indeed I was mistaken, it is 2". I don't have access to a saw right , so I can't cut it yet, But I'll update as soon as I can. Thanks for the help.

No problem. let me know if you have more questions.

can't the third bearing to meet with hobbed bolt to have pressure on filament any help

can't the third bearing to meet with hobbed bolt to have pressure on filament any help

Are you using the 3D-printed pin for the bearing? It has flats on it that should let the bearing reach.


would this kit, along with the Itty Bitty Belted Extruder Drive Kit with the belt and pulley, be all the hardware needed (except the motor and hotend)?

Yes. That kit, plus the Itty Bitty Belted Extruder Drive Kit should have everything you need.

Also, what is the difference between this:


And your extruder? they both seem to fit e3d v6 3mm...

E3D V6 3MM Version of the Itty Bitty Single Extruder

Voodoo28 made a slightly modified version of my extruder block that fits the 3mm E3Dv6 better. I think the only thing that's different is that the pocket on the bottom of the block is a little shallower. If your hot end fits snugly in the groove mount plate with no play, this isn't needed, but in most cases there is a little play and having the block press down on the top of the hot end helps stabilize it. You can use shims to take up the extra space, or you can use Voodoo28's part, which has a shallower pocket.

Thanks, you rock!

Will this work with E3D V6 hot ends?

Yes, it should.

Thank you sir.

I printed the 1.75mm extruder with built in supports and cannot seem to get enough tension on the filament. Any suggestions? If I screw the guidler in all of the way, there isn't very much tension on the filament. I am using a 608z 22mm bearing, is that correct?

For 1.75mm filament, sometimes the pin in the idler bearing comes in contact with the extruder block and prevents it from moving in close enough to grip. I have a cutout plastic pin that I use. I'll find the file and upload it shortly.

I just uploaded the 20mm plastic pin. Here are a couple of photos from my double extruder instructions that show how to install it:


Just turn insert it into the bearing. Turn it so the flat is vertical to drop it into the block, and use a sharp tool in one of the holes to rotate it and lock it in place. This should give you enough clearance to grip 1.75mm filament.

Thank you! I ended up sanding down the extruder in this area so the bearing could reach the filament, but this is a much better solution. Going to print this and another extruder body once I get my upgrades done.

Thanks again clough!

You're welcome.

Comments deleted.

I'm putting together an upgrade for an i3 for a friend. But the E3D hotend has the bowden fitting at the top. Is there any possibility of getting the 1.75 version with the small inset for the fitting in the extruder body?

I printed the current version and would rather not just bore out the material.

Quick side note is the hotend is the latest version with the upgraded thermal sensor. Will be able to print all the latest higher temp filaments. :-)

Which fitting? This one? http://e3d-online.com/E3D-v6/Full-Kit/v6-1.75mm-Universal

If so, you're probably looking for a version that allows the liner to extend all the way up to the hobbed bolt?

Yes, that is the one. I hadn't thought about the PTFE tube until you mentioned it.

Though I can't remember if the Itty Bitty Flex has it for the 1.75 version. I'm running 3mm with that one so it wasn't an issue with the HIPS and ABS that I've run so far.

Very happy with all the mods that I've gotten from you!

The Itty Bitty Double FLEX extruder (E3Dv6 1.75mm version) has the cutout for the coupler on the E3D 1.75 universal hot end.

Unfortunately it looks like the 1.75 heat sink only comes in the "universal" configuration now. I might see if I have any older heat sinks in my surplus box, but that bowden fitting at the top is giving me grief. So anyone wanting to use this with the 1.75 E3D will have the same problem with the interference. Since this is going a standard Wade's mount I don't think I can use the Double FLEX. Is the cutout hidden by the onion skin?

Yes. On the double-flex, E3D 1.75mm version, the cutout is behind the one-layer thick bridging support. Once you cut it out, there's room for the coupler.

The coupler is very small. You should be able to just carve out a little space for it with a hobby knife or a countersink. I think you can even remove it, if you push it in to release the tubing, remove the tubing, and then gently remove the coupler.

Comments deleted.

Very nice extruder. Any plans on making a bowden version for standard Nema 17?

No, I don't have any plans for that. I haven't really looked at Bowden extruders. Is there a need? Are there no other good bowden extruders available?

Work in bowden mode?

The extruder has no bowden attachment included, but if you added a bowden adapter, I think it would work.

I have a low power Nema 17 and become hot, it melt the plastic part.
Have you seen this problem with this nema 14 ?

I have not seen that with the NEMA 14 motors, but you have to use the right motor and set the current correctly on your driver. If you set the current too high, any motor will get hot.

Can I still use your improved Hexagon cooling shroud and print cooling fan system with this?

Yes. They're designed to work together.

Can a Nema 17 be mounted instead?

I don't have a NEMA 17 version of this design. It's specific to NEMA14. You could probably use a standard hinged accessible extruder body with the 80T pulley from this extruder and make it work. You would have to figure out the correct belt to use. If you know the spacing between the shafts, you can use the calculator here to find the correct belt: https://sdp-si.com/eStore/CenterDistanceDesigner

Thanks bud, You are my Maker Farm I3V Upgrade Guru!

Will this work for Ninja Flex?

I print 3mm NinjaFlex with mine all the time. In fact, I printed something with NinjaFlex yesterday.

clough42, excellent work!

Just one question: In your SolidWorks files there is a very unusual hobbed bolt design. Is it really intended to be like this?

I suppose that depends what you mean by unusual. That's a model of the standard MakerFarm hobbed bolt. Of course I didn't model the threads in that version. Some of my other extruder designs have a version with the threads modeled.

The bolts are index-milled, similar to the ones described here: http://www.re3d.org/getting-a-grip-part-1/

this might help?
Nice extruder design!

Hobbing fixture for mill

Thanks a lot. That's exactly what I asked about. It's way ahead of usual "rotating tap" design.

I just uploaded an experimental 1.75mm version of the extruder block. If you try it, let me know how it works.

Do you possibly have a hardware kit for this extruder? I'm looking for something a little cheaper than the itty bitty double and this looks like it would fit perfectly. I assume most of these pieces are similar to the itty bitty double? A kit with everything but the printed parts would be swell!

This extruder uses the same bearings and screws as the standard hinged accessible extruder, so you can reuse almost everything. You will need a drive kit (belt and pulley) and a motor. I have both available.


Two main problems:
-I don't have the parts for Greg's extruder (not currently using it), but I guess I could purchase http://www.makerfarm.com/index.php/extruders/greg-s-hinged-accessible-extruder-hardware-only-no-printed-parts.html which would have all the required components?
-I live in Canada and based on your website you don't ship here currently, do you have a recommended international seller that provides these parts? Or do you have any plans of shipping to Canada in the near future?

Yes. We already offer the double extruder hardware kit for international purchase through eBay. We'll be adding the single extruder kit and versions with motors sometime in the next week.

What are the specs on your NEMA 14 stepper? I have always disliked the slow retraction on my Makerfarm i3, topping out at about 13mm/s reliably. I'd love to upgrade to this sweet light extruder but the NEMA 14 motor specs range from like 9 ozin to 56 ozin. The torque or just the body size of the motor would help. I'm looking at 0.8A 25oz*in motors that are 34mm.

Derp! I completely glossed over the link to the stepper specs in the instructions. For others who might have gotten lost: 34mm, 0.8A, 15N.cm (21oz.in). You can buy them direct from clough42's store, which I did along with the belt. So easy!

my nema 14 chatters i can not get a smooth rotation. I have changed the stepper board and the still just chatter. Makerfarm pursa.
any suggestions

There are two possibilities: either the mechanism is jammed or there is something going on with the wiring. Try running it without the belt. If it turns smoothly without the belt, try a little finger pressure on the motor shaft to make sure it's producing torque. If it chatters without the belt, check your wiring. Unplug the connector at the controller board. With a multimeter, you should see a few ohms resistance between pins 1 and 2 and a few ohms between pins 3 and 4. All other combinations should show open circuit. Check for loose wires or pins not seated in the connectors.

So possibly a dumb question...can you use 608zz bearings? if I understand bearings, the zz on the 608 just means it has seals over the ball bearings, so they should be the same as a 608.

I am using 608ZZ (double shield) bearings. They're pretty standard in the RepRap community. Some people like the rubber sealed ones (608-2RS) but I haven't tried them yet.

Awesome! I just got it [itty bitty] all together. I just got the stepper, pully, and belt I bought from you, so now all I have left is to install!

Also, gotta point out: the added lollipop in the package totally made my day!

I'm glad you liked it. I got one in a package of helicopter parts I ordered a couple of years ago, and it made me smile. It's just something fun that I do.

Do you happen to have a bracket available for RepRap style Prusa i3 that runs on smooth rods? I want to convert to v-rail but dont know what I need for that?? :/

This extruder should mount anywhere you can mount a normal accessible or hinged extruder. The footprint and mounting holes are the same.

Very nice print, thanks for posting, mine is off and running !
It really reduced the mass swinging back and forth, my edges seem to be cleaner.

You're welcome. I'm glad you're enjoying it.

added to my must build list..
Waiting on my 12" i3v
ordered 2 Nema 14 from OMC PN# 14HS13-0804S 9$
but any chance you can edit the model to use a Nema 11 5:18:1 or a NEMA 8 (4.75:1) geared steppers
i have a lot of them from omc-stepperonline
models i have on hand

Hmm...You ought to be able to build an adapter plate to mount those up to the existing holes. I'll be interested to see how the 14HS13-0804S works for you. It looks like it has plenty of torque, but the resistance and Inductance are a tad high. Watch your retracts and make sure it isn't missing steps on high-speed moves. If it does, you can just slow down the retract a little and it'll be fine.

I'm setup for 24+v so i think it will be fine.
(well 5v to 30v Diy SMPS 0.4mv ripple at a 45amp draw. built to drive 85amps at 12v or 70 amps at 30v)
have you asked Colin maybe he can make and sell hardware kits for this and the other dual extruder setup ?
or maybe even offer them as upgrades ??? worth asking seams like a really cool guy to work with

problem with geared steppers is shorter shafts don't leave a lot for a plate but i will give it a shot maybe flip the pulley.
I'm working on a AIO Dual Extruder/hotend direct drive using 8HS15-0604S-PG19

also have you tried using a GT2-16 pulley 16 tooth might bump up the tq and rez a bit more

another thing i like to do is make the filament pathways fit PTFE tubing (4mm for 1.75 5.8~6mm for 3mm)
to reduce binding Plus you can push it all the way to the gear fixing a lot of problems with high shore products like Ninjaflex
seam like a little thing but has made a massive impact on how fast i can print with the stock wade setup.
with your dual extruder i think it will help even more

At 24V, that motor should work great.

I'm working on hardware kits, and I am discussing options with Colin. More info soon. I have done some testing with the 16T pulley, but haven't yet found the need for the torque.

I had been thinking about the PTFE tubing. You typically use 4mm I.d. for 3mm filament and 2mm for 1.75?

I use 4mm OD measured 2.09mm ID for 1.75. I have yet to do a 3mm bowden setup so not sure I think it's 5.8 to 6mm od with a 3.75 ish id. It's not really about the tq as mush as rez with 3mm fine control. .with 1.75 I don't really see the need for that extra rez really. think of it as steps per 1mm^3 of extrusion

Thanks for this nice design! I've made one yesterday and while I'm still battling with some (i think) extrusion-related problems like bad corners on certain layers and the top not being completely solid, it looks like a really nice design.
The extruder is noticeably more silent than the makerfarm one, and I guess the lower moving mass will also have it's positive effects (on vibration etc.).
What values are you using for Acceleration / max speed with this extruder?

Right now, I'm just using the defaults (0) in Slic3r. I'm using the defaults in Marlin:

define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,644.2} // Itty Bitty Belted Extruder

//#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,841} // MakerFarm Default

define DEFAULT_MAX_FEEDRATE {250, 250, 2, 22} // (mm/sec)

define DEFAULT_MAX_ACCELERATION {1000,1000,5,1000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

define DEFAULT_ACCELERATION 500 // X, Y, Z and E max acceleration in mm/s^2 for printing moves

define DEFAULT_RETRACT_ACCELERATION 500 // X, Y, Z and E max acceleration in mm/s^2 for r retracts

// Offset of the extruders (uncomment if using more than one and relying on firmware to position when changing).
// The offset has to be X=0, Y=0 for the extruder 0 hotend (default extruder).
// For the other hotends it is their distance from the extruder 0 hotend.
// #define EXTRUDER_OFFSET_X {0.0, 20.00} // (in mm) for each extruder, offset of the hotend on the X axis
// #define EXTRUDER_OFFSET_Y {0.0, 5.00} // (in mm) for each extruder, offset of the hotend on the Y axis

// The speed change that does not require acceleration (i.e. the software might assume it can be done instantaneously)

define DEFAULT_XYJERK 20.0 // (mm/sec)

define DEFAULT_ZJERK 0.4 // (mm/sec)

define DEFAULT_EJERK 5.0 // (mm/sec)

Can i just replace the current gears with those two (in addition to the gt2 belt)?

Yes and no. You may be able to get it to work, but you may need a different length belt. The other issue is that the forces are reversed when switching to a belt, so the pressure on the front bearing will try to pull it toward the open side of its seat instead of burying it into the frame where it has good support.

Isn't the belt should be in a close loop?

Yes. The belt is a closed loop. But the center-to-center distance may be different for a different extruder, so you may need one with a different number of teeth.

did you print the belt? if not can you send a link to buy one

The belt is a standard Gates GT2 belt, listed in the instructions. Search eBay for 2GT-188 if you want one for this extruder. If you want one for a different extruder, you may want a different length.

That looks like the right one. There are also chinese sellers all over ebay. Just search for 188-2GT. The pulleys can also be had there. Auctions for the 20t aluminum pulleys regularly complete for under $2.

Thank you. Would it be possible for you to compile a version for 1.75 filament?

This is something I can work on. I don't have a 1.75mm hot end, though, so I'll need someone to test it.

Were you ever able to work on the 1.75mm version? I can imagine your time has gone into the double extruder. I have a 1.75mm hexagon and I am willing to test for you. I have broken two gears which I think is due to the extruder frame not having the holes for the stepper far enough out, so there is no adjustment available. I think that a belted system would be easier to adjust, plus the weight benefits would be nice. I have your hexagon cooling and ABL parts and am very impressed with them. Thanks

Yet another project that hasn't gotten any love from me recently. I'll contact you privately with an experimental version and post it here if it works for you.

I'll add my name to the list of those hoping for a 1.75mm filament version. Looks like a really good design.

Yes. Here's a link to an experimental version for 1.75mm filament. There two versions of the 1.75mm block--one with relatively loose channels and one with narrower channels. This is still a work in progress, so please try it out and let me know how it works for you.


Very excited about the 1.75 version. I've ordered the parts from your site and will report back my success or failure.

Thank you for the 1.75mm version. It worked from the first try.

Hello, where did you source the closed belt from?

Recently I found interacting version of the extruder - it comes with internal bed level sensor without servo!
what do you think?

LUCAS extruder - finally a really universal extruder

That extruder has some promising-looking features. It'll be interesting to see how it all works out.

Greetings... Any chance you could share your slic3r settings for this part? I am still not sure what infill to choose and when. Also, did you print all the parts in one plate?
Thanks for all your contributions. I'm printing my way though your collections.

Sorry I don't have the file uploaded yet. I ended up in the hospital instead . I should be home later today and I can do it then.

I usually don't print parts together for a couple of reasons. The extruder body is a relatively large part and prone to warping if your bed adhesion is at all suspect. Also, the pulley needs to be super clean to work well, and crossing perimeters to print several parts at once can leave little bits of plastic in the grooves if your retraction isn't perfect.

I can upload the file when I get home tonight. I'm printing with a .4mm hexagon hot end using .2mm layers. The support material assumes this .2mm layer height.

Great. I am mostly concerned about infill and layer height. I am using a .3 nozz on a Hexagon. I went ahead and printed the three main parts shortly after I posted these questions and did find the edge of the gear a bit rough, but the belt seems to sit ok in it. I am not sure what I did wrong (other than too many parts at once) but the hobbed bolt hole is around 7.56mm. I'll reprint the gear by itself to see if that helps.

Every printer/nozzle/filament/speed/slicer combination will render fine details like the teeth on the pulley a little differently. I uploaded the openscad file for the pulley, so you should be able to make adjustments as needed. It has a couple of parameters fro controlling the exact tooth profile to account for the distortions created by different printers.
If I remember correctly, I made the hole in the large pulley undersize so it would fit tightly on the threaded portion of the hobbed bolt. This works great for the MakerFarm bolt I'm using, but you may need to change size if it's sitting on the shoulder of your bolt or if your printer distorts round holes differently than mine. The openscad file has all of these parameters in it.

I just uploaded another video of the extruder pushing material fast enough to bridge at 120mm/s. No issues at all. I'm very pleased with the results.

One more comment from me about noise. I found that pololu DRV8825 stepper driver much less noise http://www.youtube.com/watch?v=tGd2ulVkDTMhttp://www.youtube.com/watch?v...

Hey, I've been printing a lot of your upgrades! This also looks great, though I plan on eventually moving to a bowden instead(I'm going to upgrade to dual extruders).
I too have been tracking down noise, and I've found the machine likes to vibrate bolts in random places a lot... currently getting that Y bed noise too.

The other place mine vibrates is the X belt. At a certain step rate, it vibrates like a guitar string and slaps the extrusion. I've tried making it tighter, but it just rings at a different speed. Right now, I have it fairly loose, which I understand to be the intent with the GT2 design, and it's pretty tolerable. Even when it does slap it isn't too loud.
Do you have a specific dual extruder bowden setup you're looking at, or are you designing something fresh? I looked around and didn't find anything that I felt was already integrated, with the bugs worked out. I also saw a bunch of comments from people who came to direct drive from bowden and questioned why anyone wanted to go back to the hysteresis and ooze challenges.

I just installed a stepper dampener on my I3V x-axis motor and it's made it much quiter. I still have the belt slapping issue, though. I plan on wraping some velcro around the belt at the right point to dampen it.

I tried sticking a couple of pieces of the soft side of the velcro to the extrusion to keep the belt from slapping, and it works perfectly. What a great idea! Thanks.

That's a great idea. I was thinking about making a block that just touched the top of the top belt at the left side of the extrusion to prevent the oscillation, but I didn't like the idea of wearing the back of the belt. Are you thinking about actually attaching the velcro to the belt, or to the extrusion?

If you want to reduce weight(moving mass), why not remove heavy protruding parts, such as fan and deploy the motor so that it was close to the X-axis, it would reduce the lever and weight.

The pictures of the model are insane... solidworks?

SolidWorks. It's a nice tool set.

Why don't use Bowden to decrease moving mass?

I don't have any experience with Bowden systems. From what I've read, direct drive systems are a lot more precise and easy to control. I couldn't find any existing designs that use Nema 14 motors, but my math says it should work, so I decided to give it a try.

One more question. From your video I hear that your greatly upgraded i3v makes a noise when moving X and Y, do you try dampers or decrease current on motor drivers to reduce that noise? I have the same(but maybe slightly more) noise on my i3 version with printed linear bushings (http://www.thingiverse.com/thing:102482http://www.thingiverse.com/thi... ). I tried to use printed dampers (http://www.thingiverse.com/thing:390323)http://www.thingiverse.com/thi..., it works, but not as goo? as needed

PLA printed LM8UU bearing noise test!
by jspark
Experimental NEMA17 DAMPER for noise reduction

I've been hunting down and killing noises on my printer since I built it. It's tough to tell from video because the auto gain control in the camera tries to maintain audio levels. The quieter the printer gets overall, the more gain it applies to whatever is left. At this point, the Y bed movement is the loudest thing on the printer. It's actually quite quiet, but I'll probably chase it down anyway.
I think the motors Colin is shipping are these: http://www.circuitspecialists.com/nema_17_stepper_motor_42bygh4807.htmlhttp://www.circuitspecialists....
They're .5A motors, but the drivers are set to about 1.2A by default and according to his instructions. This is why they get so hot. Fortunately, they're 19ohm coils, so they only manage to draw about .7A, but this situation could easily be causing excess vibration. The coils are also 32mH, which limits the step rate severely, which is why it won't extract over about 10mm/s without skipping. I think this also makes the microstepping uneven and may be what causes the shimmery texture on the sides of the printed parts. Come to think of it, this probably also adds lower frequency components to the vibration.