Itty Bitty Double Extruder (with mount for MakerFarm Prusa i3v)

by clough42, published

Itty Bitty Double Extruder (with mount for MakerFarm Prusa i3v) by clough42 Nov 27, 2014
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UPDATE: a hardware kit is now available! click here

I am proud to present the Itty Bitty Double Extruder, a two-material belt-driven extruder with mounting hardware for MakerFarm i3v printers.

Versions are provided for 3mm and 1.75mm filament.

The extruder should be easily mountable on any printer that can accept a standard Hinged Accessible Extruder.


  • For Original Hexagon hot ends on 20mm centers (NOTE: NOT Hexagon AO)
  • NEMA 14 motors
  • GT2 belt drives with printed pulleys
  • Integrated servo Z probe
  • Cam-lock idler bearing pins
  • Uses standard hobbed bolts available here
  • 2mm narrower and 2g lighter than the stock MakerFarm extruder
  • Includes mounts for Prusa i3v with integrated hot end cooling

Discussion thread: http://3dprintboard.com/showthread.php?8848-Itty-Bitty-Double-Extruder

See the instructions for a list of vitamins.

Note: You will want to use firmware that will lift the Z axis when deploying and stowing the probe to keep it from hitting the bed. If you're using Marlin, you may wish to check out this thread: http://3dprintboard.com/showthread.php?6165-Marlin-firmware-fork-for-MakerFarm-i3v-w-auto-bed-level-amp-Roxy-s-enhancements


Detailed, step-by-step assembly and calibration instructions can be found here: http://clough42.com/instructions/ibde-assembly/

Files are provided for 3mm and 1.75mm versions of the extruder. You can print all of the pieces separately, or you can print the provided plates of multiple parts. You will need to print:

  • IttyBittyDoublePlate1.STL
  • IttyBittyDoublePlate2-1.75mm.STL or IttyBittyDoublePlate2-3mm.STL
  • Two copies of Parametric-Pulley-80-8-hex.STL (these will fit on Plate 1 if your printer can print a whole bed of parts cleanly without oozing or warping)

In addition to the printed parts, you will need the following vitamins:

  • Hobbed bolts with nuts (2)
  • Hexagon hot ends (NOTE: NOT Hexagon AO) (2)
  • NEMA 14 stepper motors (2)
  • HXT-900 servo available here
  • Z probe switch
  • 25x25x10mm Fan
  • 40mm fan
    • for print cooling
  • RAMPS fan extender
    • if using software fan on RAMPS
  • Stepper driver
    • if your RAMPS board only has four
  • Hardware kit available here:
    • GT2 20-tooth Pulleys with set screws (2)
    • GT2 200mm Belts (2)
    • 688ZZ 8x16x5mm Bearings (6)
    • Extension springs (2)
    • Fiberglass/Polyimide insulator
    • M2.5x10 socket head cap screws (2)
    • M4x.7 hex nuts (2)
    • M4x20 button head cap screws (2)
    • M3 flat washers (6)
    • M3x.5 hex nuts (11)
    • M3x25 socket head cap screws (3)
    • M3x16 button head socket cap screws (10)
    • M3x12 flat head socket cap screws (10)
    • M3x8 socket head cap screws (6)
    • M3x6 button head socket cap screws (2)

Assembly notes:

  • Heat new Hexagon hot ends to temperature and tighten both the nozzle and the down tube into the heat block before installing in the printer. If you do not do this, they will leak.
  • Remove the support material from the bottom of the filament channels
  • You can install the double groove mount either side up, depending on how your printer bridges the bottom of the hot end pockets. It should hold the hot ends firmly and be flush to the bottom of the block.
  • The 25mm fan should be installed with the air blowing up (drawing air in over the hot ends)
  • Make an insulator with some fiberglass and Kapton tape to install above the hot end heat blocks. If you don't the hot end cooling shroud will melt.
  • You can feed all of the wires up through the channel in the center of the block. Force in some scraps of 3mm filament and zip tie as a strain relief.
  • You will need to orient the heat blocks properly for the wires and Z probe to clear. See photos.
  • You may need to adjust your X carriage so the extruder tips are at the same height. As long as you're using auto-bed-leveling, you can usually get enough adjustment by turning one of the Z motors by hand to tilt the whole X axis.

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That's Really nice, I want to put it in my Prusa Air 2, but I don't know if I should change the electronics to accept double extruder or I can work with the same I have??

What electronics do you have on the printer now?

I just about have mine set up, just need to wire everything :P But it seems as if my hardware kit didn't have the Z probe in it. It has the servo and all, just not the black part that "taps off" and recognizes the bed. Is there one on amazon I could order? Or any trusted seller, but preferably Amazon. Thank you! This an absolutely amazing design by the way, I look forward to the first test of it.

The switch is just a normal snap switch. My favorite is this one: http://www.digikey.com/product-search/en?KeyWords=SW1005-ND

It has no lever and has a very low actuation pressure, so it is very precise. It's probably overkill. You can actually use the Z switch that your printer came with if you don't want to buy a new one. The probe replaces the normal Z leveling mechanism on the printer.

If you decide to use a switch with a lever on it, you might consider printing the Z probe arm from the new V2 double flex extruder here: http://www.thingiverse.com/thing:1234779

It has more holes and makes it easier to line up the tip of the lever arm directly under the servo for maximum precision.

Itty Bitty Double FLEX V2 Extruder (With mount for MakerFarm Printers)
Comments deleted.

Wow nice work. What software did you use for these renderings?

The renderings are done in SolidWorks.

One more question: What steps/mm are you using, assuming a 1.8*/step and x16 microstepping, which is the norm? I'm using 436 steps/mm or so, but I'm not sure if I should take the belt pitch and/or pulley teeth into account.

The only things you should take into account are the motor steps per revolution, the microstepping, the drive ratio (4:1 for all my extruders) and the effective hob diameter. I use 644.2 for all of my extruders with good results.

Huh, okay. I'm finding a good result at 873.06. Loving this extruder design --- just got my second hotend and looking forwards to setting it up. One slight thing, though. It seems that the Makerfarm hobbed bolts are actually too deep for there to be sufficient pressure against 1.75mm filament --- I had to switch to a shallower hobbed bolt for there to be adequate force against the filament. Both my Makerfarm hobbed bolts are this deep. Am I just doing something wrong? This current method works fine, but I'm just wondering.

I don't know. I have tested with 1.75, but I don't run it regularly. Is the bearing contacting the bolt, or is it the extruder design that's preventing it from making close enough contact? I can fix that, but I can't do much about the bolts.

It seems that it was just one specific bolt that was bad for me. Swapped it out, and now I'm printing great!

2-color tree frog

Glad you figured it out. Thanks for letting us know.

Sadly, it seems to be the bolt.

has anybody tried flexible filament with this extruder?

This extruder is not ideal for flexible filament, due to the long, curved filament path. I have a new design specifically to support flexible filament here: http://www.thingiverse.com/thing:757864

Itty Bitty Double FLEX Extruder (with mount for MakerFarm Printers)

I have a question: Is the fiberglass insulation strictly necessary? If it is, where would it be possible to get some?

Without the insulation, the printed shroud for cooling the Hexagon hot ends will droop and melt onto the heat blocks. You can make your own with fiberglass strips and Kapton tape. If you don't want to bother, I have pre-made insulators available through my web site. http://clough42.com/shop

You still have to cut slots for the hot ends with scissors to fit whichever extruder you're building.

Also, one comment about your website. It would be really nice if a shipping time estimate could be displayed at the order page.

Thanks for the suggestion. I'll see if I can add that. Orders typically ship the following business day and delivery time is determined by the carrier. USPS is currently quoting "1-3 business days" for Priority Mail and "within 3 business days" for First-Class, but they do not offer a guarantee.

Great! Sorry — I didn't realize that you were selling the fiberglass strips separately. I'll certainly order one!


Can I use nema 17 instead of nema 14 motors?


My design uses NEMA 14 motors for light weight and compatness. If you want to use NEMA 17 motors, there is a derived thing down in the Remixes section to accomodate these motors. I have not personally tried it, so I don't know how it works.

This is really a nice looking design. I love people that contribute to the open community like this. I am pretty new to the scene, but hope to be there soon. I have a question about your design, if you don't mind. I have a hexagon hod end like the one in your model, and I am curious how you are getting away with little to no air flow on the fins. I bought my kit though MakerFarm, and I wired my fan directly to the power supply. I was instructed to do this with my particular hot end, and didn't question it. I found your print because I am looking at a fan shroud like yours for the print. I am just curious if I can get away with not cooling my hexagon and cooling the print instead. Are their disadvantages to that? I also read that a print fan is primarily for PLA, I want to improve my ABS prints. Sorry if this is not the right place to be asking these questions. You just seem to know a ton about what you are doing.

There is a 25mm fan behind the extruder that draws air in the front, over the hot ends to cool them. Hexagon hot ends require constant cooling air to maintain a sharp heat break and prevent jamming.

Feb 2, 2015 - Modified Feb 2, 2015

First, this is amazing. The design is unreal and I can't wait to get this running. I just have one question, what do you have covering the bottoms of your hot ends? Did you print those covers? I can't tell if it's actually just the bottom of the hot end or a cover.

The last batch of hot ends I ordered came with those covers. I think RRD calls them isolators. They keep stray plastic from building up on the hot end, and they insulate the hot end so the temp doesn't drop as much when the print cooling fan kicks on.

Thanks for the quick response. Where did you order your Hot Ends from? I want to make sure mine have them too as I've always had a problem with plastic building up on the hot end.

I just confirmed today that all hot ends in stock at MakerFarm now have the rubber isolators.

Hey Clough42,

Your dual extruder is running great on my setup! Having a lot of fun experimenting with multiple filament prints! I do wish there was a way to fine tune the hot end z distance manually though. I have an old hexagon hot end that I'm running with one of the newer ones and there is a little bit of difference in the two. I'm probably just going to get another newer one, but it would be nice to be able to adjust the z height of them both manually. Not sure the best way of doing this, but thought I'd just throw it out there.

Also which hot end are you calibrating your bed probe offsets to? I mapped my offsets to the hot end furthest away from the probe, but curious if it really makes a difference?


If you're running auto-bed-leveling, you can just rack the whole X carriage or level the bed to the nozzles, as long as they aren't too far off. The procedure is here:


You might also consider putting a shim between the top of the hot and and the block on the short side.

With the nozzles at the same height, there's only one Z offset to worry about.

If you aren't

That worked out great! Your calibration documentation was extremely helpful. No need for shims, as the height difference between hot ends was able to be adjusted as you described. I am now just trying to get my Slic3r settings adjusted to avoid cross contamination between filaments...

Thanks again!

Just an Update:

After finally adjusting the E Steps, things are printing amazingly! Wish I would have figured this out sooner.


First off, great design, both form and function! I got it up and running over the weekend and it's working great! Just have the print fan left to install.
My question is regarding the servo for the auto bed leveling and the RAMPS fan extender co-existing. I'm wondering how you have your servo connected when the fan extender takes up all the servo ports?
Any advice would be appreciated!

I cheated. The RAMPS Fan Extender fits over all four sets of servo pins, but it only uses the last two. So the first servo connector, where the Z probe servo should be is covered, but not used. I just soldered a 3-pin connector to the top of the fan extender board to pass the signals through, and I plug the servo in there.

Just got it working the way you described. My soldering isn't very pretty but it's doing the job! Thanks for the tip!

Note that I think this only works with the RRD fan extender. The Geetech extender seems to be wired on D11/D6 instead of D4/D5. I'm still investigating that.

An update...the Geetech extender uses the first two servo connectors, so you can just shift it two pins to the right, so it's plugged into D4/D5 only and you can control two fans while leaving D11 open for your ABL servo.

Question: Would it be possible to get a hardware kit without the bearings, belts, and belt pulleys? That would help quite a bit. Maybe it would be possible to use the Ebay preference select box, similar to http://www.ebay.com/itm/3D-Printer-Filament-1kg-2-2lb-1-75mm-3mm-ABS-PLA-MakerBot-RepRap-/261464565916?pt=LH_DefaultDomain_0&var=&hash=item3ce080a89c

At this point, I am just offering the complete hardware kits, but I will definitely think about that for the future.

Okay, good to know.

This is an incredible design! I use an E3Dv6 hotend , how difficult would it be for me to modify this to accommodate the E3D vs. the hexagon? I imagine the only changes would have to be with the groved plate and the double shroud right?

I'm not familiar with the E3dv6, but others have asked about it. How close can they be placed? This extruder has the hot ends on 20mm centers, and it was my understanding that the E3Dv6 couldn't be placed that close.

I also want to request if you could make version of this for E3Dv6. I already have a dual extrusion setup for the i3v using them, but I would very much like to have an even smaller carriage.
Also, I was thinking in my head....what if you mount two hotends parallel to the Y axis instead of the X? I think there is more than enough 'extra' Y axis instead of x?

it looks like at the very closest you're looking at 22.3mm, according to the documentation found here: http://e3d-online.com/E3D-v6-Documentation. Not sure if there's an easy way to bring them closer other than shaving down the heat sinks on both, bummer!

Bought the vitamin/hardware kit from you and very excited about this.

  • I'm currently printing this in PLA, and realized that the extruder motors may get hot enough to reconsider this material... should I be doing this in ABS?

I recommend ABS. Especially for the fan shroud, since it's near the hot ends. I think it's also less brittle and will have less friction in the curved feed channels. If you do try PLA, let us know how it works.

I'd you use the Pololu 1209 motor and keep the current low, the motor heat should be okay.

Roger that.

These are beautiful pieces; it'll be an interesting experiment to duplicate them in ABS. The PLA parts came out glossy and gorgeous. I purchased the Pololu 1209s on your previous recommendation.

I've had less luck printing well with my ABS filaments, which are drying in my oven as I write this. (I hope this will create a less acne pocked print.) I may end up mixing up materials in the final build, but will ensure ABS for the shroud.

Where did you get the connectors you have mounted just to the right of your lcd screen? Are those use to make it easy to swap out your extruder?

Jan 7, 2015 - Modified Jan 7, 2015
clough42 - in reply to redman_no1

Those are 9-pin Amp CPC connectors, size 11. The first one connects the two fans, servo and z probe switch. The others are for the extruders, each with a motor, heater and thermistor. I did it so I can easily swap in prototype extruders.

Is the mount for the circular connectors available somewhere? It almost looks like you re-purposed 40mm fan mounts, but a quick search didn't turn up anything. I was going to use molex connectors but this is so much more elegant. Great job!

I just uploaded the extruder connector block: http://www.thingiverse.com/thing:1228536

Extruder Connector Block

Great work! My compliments

Thank you.

If anyone is interested, I now have a hardware kit available with the screws, bearings, springs, belts and pulleys to assemble the extruder. http://www.ebay.com/itm/Itty-Bitty-Double-Extruder-Hardware-Kit-for-Makerfarm-or-Reprap-3D-Printer-/161542799817

Man that is some-kind-of-NICE!

Thank you. I'm pretty happy with the way it turned out.

Can someone link me to an x carrage for a prusa i3 that will hold this extruder????

Also, http://www.thingiverse.com/thing:607891

Which is the one I will probably use on my next build...

Prusa i3 / P3Steel Improved X-axis Printed Parts Collection
I3 Rework / Wilson X-Carriage for T2.5 belt (with SW source)

Hi 'gr3eg0ee',

I've built this extruder and helped 'clough42' do some initial testing. I have a Makerfarm i3 with the rods instead of the v-slots. I've designed a simple system to mount it to that printer that allows adjustment of the two extruders. It also does not ruin your printer should you want to put your old extruder back on. It only take 3 bolts and you need to drill two small holes.

If you'd be interested in it I can post it. I need to do a bit of work on it so it's ready for the mass public bit I'm willing to do that.

Let me know if your Prusa is a Makerfarm or not. I'm not sure if "i3" is a designation that only Makerfarm uses. I know there are other Prusa models out there.

yes i would love if you could post that :), and no it is not a makerfarm its just a generic one that i sorced all the parts for :) just need a system to mount it on the rods. and was wondering if anyone had made one before i got to the trouble of designing one :)

This looks great! I can't wait to get working on it.

I must say beautifully modeled! Getting my first printer soon once i get some prints under my belt i have a feeling this will be on the //todo list.

This is great. I have been wanting to upgrade to dual extrusion. I have not had time to figure it out. Thank you for this great design. I will try order the parts next week. I have made several of your other improvements as well. I really like the cooling fan in the x carriage rather than on the hotends. That has made my printer great.

If you already have a i3v, How much do the extra parts cost?

~Going to make this for myself as well love the design.

I'm working on a better organized shopping list with sources. If there's enough interest, I may put together some kits.

I'ld be interested in purchasing some sort of hardware kit, I've already started printing the itty bitty extruder parts.

Definitely interested as well

What size print bed were the plates made for? And do you have a link for where to get the bolts and nuts?

The plates are laid out for the 8" bed. You will need a printer with excellent adhesion to print the plates. If you typically see a lot of warping, you will want to print the parts separately. The pulley teeth need to be very clean to function well. I print with a .4mm hexagon, .2mm layers and they turn out well for me.

I have not yet assembled a hardware kit, but I'm thinking about putting one together.

After checking a couple places, all the vitamins are going to cost from a third of the price of the printer itself. This may take me a while to get put together.

Excellent work! Any dual color prints to show? Further re-enforces my argument for a upgrade to my MFi3.
Keep up the good work.

Yes. Here's my first print with the dual: http://www.thingiverse.com/make:104783

Still needs some temperature tweaking.

Two Colour(Color) Spiral Cup

Is there any adjustment to the nozzle height to even them out?

If the hot ends are the same length (mine are) only fine adjustment is necessary, and you can just tilt the whole X axis slightly (turning the motors by hand). As long as you're using auto-bed-leveling, the printer will compensate. Other ideas might include replacing the spacer on one of the top v-slot wheels with a cam.

This is incredible! You've outdone yourself. I love the idea of a belt driven extruder. Fantastic! Mind blown.

Thank you for the compliment. I'm very happy with the way it turned out.

Making one now. A work of art.