Dual X-Carriage Bukobot 3D Printer

by buildrob, published

Dual X-Carriage Bukobot 3D Printer by buildrob Jul 17, 2013
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Do you have problems with filament ooze on your dual extruder prints? Perhaps this idea might help you.

This page describes the adaptation of a Bukobot Duo (Original 2012 Version) by Deezmaker to have two x-carriages which can be driven independently instead of the normal single x-carriage with two extruders. The change allows you to park the inactive extruder and prevent it from oozing onto the print when the other extruder is active.

In addition to improving dual-extruder printing, the firmware for this design has also been extended to allow you to print two copies of the same object at once (with the heads printing at an arbitrary position and temperature offset). This doubles your printer's output in this case. (see video below)

Advantages of separate x-carriages:

  • The inactive extruder can be parked when not in use.
  • The inactive extruder can be easily capped when parked to prevent runout/ooze (which makes restarting the print more accurate).
  • Each x-carriage is almost half the weight which allows higher print speeds with less backlash.
  • The x-carriages can duplicate one another allow two copies of an object to be printed at one.
  • support for the specification of a Z height offset between the extruder hot ends (if your extruders are not identical).

[One other technique some people have used to overcome this problem is to cool the inactive extruder below the oozing temperature at every tool head change. However this massively increases the print time as the printer must wait for the extruder to reach operating temperature at each extruder change,]

Short video of operation: http://youtu.be/BHHAHQsAeuA

Demo of Duplication Mode: http://youtu.be/Mdj5iZ5B2Dg

Tour of printer: http://youtu.be/jAfktjeuPZ4

Picture of original Bukobot Duo here: http://bukobot.com/_detail/buildrob-wiring.jpg

The above awesome dragon print model is by tbuser (here: http://www.thingiverse.com/thing:29088 ). The Ocotpus print is by moleofproduction I've also added links to other 2 color models I've printed in the comments below.


The original Bukobot Duo was actually made up of two single extruder carriages held together with a linking plate and so this modification is accomplished largely by removing the linkage plate, adding additional linear bearings, stepper motor, stepper driver, idler pulleys, synchronmesh cable, end-stop and modifying the X-ends.

Full build instructions can be found here: http://bukobot.com/creating-a-dual-x-carriage-bukobot

The Bukobot is a fantastic printer. This is not a design fault with the printer but rather a problem common to all dual extruder printers currently out there.

By the way, the latest Bukobot Duo design from Bukobot now uses a combined x-carriage which cannot be split. You would likely need to ask Diego for longer X-axis beams, rods and synchromesh cable to fit two of the current X-carriage designs (but that is one of the design features of the Bukobots, i.e., that they can be easily expanded in any direction just by lengthing some rods, beams & cables).

The Marlin firmware changes I made to support the Dual X-carriage mode are now integrated into the Marlin github baseline. See Configuration_adv.h.

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Hey Robert

i finished upgrading a big printer into a dual X carriage

and everything works great, awesome job on the marlin :")

is there a command or a way to offset the Z between non identical hot ends?
(im currently using shims but it would be nice to know if it could be made via software)

ill add pics and a video later if you want

Dear Robert, what extruder polymer item you are using infront of gearbox? is that open source or? Can you share it's stl?
Thank you!

hi, in marlin the number of extruders is 1 or 2?

In Marlin the number of extruders is set to 2. The Rumba should be able to be made to work although you would need to work out what pin numbers to use for the 6th (X2) motor drive.

thanks , now i can start :)

I am assuming here that you would drive both your Z axis steppers off the same driver (that's what I do anyway).

I made a small hack to marlin to support dual fans for active extruder og both in duplication mode. https://github.com/ErikZalm/Marlin/pull/730https://github.com/ErikZalm/Ma...

Your url doesn't exists. Can you tell me what changes did you made? Thanks.

Hey. Was inspirred by your build/machine. So rebuild my old Prusa i2 to dual x carriage. I have som problems with marlin and homing and offsets. Do you use osftware limits or only hardware or both? I have both min and max endstop on X. And a small thing, how do you control 2 fans? Se link for video/pictures https://plus.google.com/photos/101171137569571196735/albums/5969390905653934209?authkey=CLKKvO2V8ovh1wEhttps://plus.google.com/photos...

I normally just change the X2_MAX_POS value and re-upload (to save me changing it manually each time). I determine this value using the dual-extruder calibration scripts which whosawhatsis wrote here: http://whosawhatsis.com/paraphernalia/offset_test_generator.htmlhttp://whosawhatsis.com/paraph... (with X = 0 offset)

Seeing how my 3D printer not running yet & would like to do this setup, can you print the parts needed for me.


This is all a custom modification to the original Bukobot Duo. Deezmaker have also changed the design of the Bukobot (V2) so that the heads aren't separable - you can see it on their website. The nozzle scrapers are just metal strips cut from a cheap $2 hand beater (covered in some tape and wrapped with a replaceable length of pipe cleaner). I describe all the construction in the Instructions sections. Thanks for the comment. Rob.

Hi, what software you are using for slicing?

HI, if you set DEFAULT_DUAL_X_CARRIAGE_MODE to 1 or issue M605 S1 then you can use any slicer software. In the auto-park mode the slicer doesn't not have to be aware that there are two x-carriages because the firmware handles the parking and unparking of the heads. I used unmodified Slic3r.

Dear buildrob - what d you mean by "I used unmodified Slic3r."? What version it is?
Thank you!

The Slic3r software was not modified in anyway to support use of the dual x-carriages. I simply configured the software to use 2 extruders and have a zero X/Y offset between the two extruders. I used 0.99 and 1.0 but any version should work.

Thank you Sir for support and your time!

Those nozzle scrapers, did you made them or are they stock with a Bukobot?

Hi, these are made from the blades of a $2 Chinese hand-beater (wrapped with a bit of tape and pipe cleaner) - not standard. This is described in the build instructions.

I've added a video of the new duplication mode I've added to the Marlin firmware. http://youtu.be/Mdj5iZ5B2Dghttp://youtu.be/Mdj5iZ5B2Dg (Octopus model used is by http://www.thingiverse.com/moleofproduction)http://www.thingiverse.com/mol...

If anyone is thing of copying this, I made an additional change which you might want to consider:

This dual-x carriage design requires that the distance between the two endstops is properly calibrated to ensure that the printing from the two extruders is aligned. I found that that the variability in triggering of the mechanical microswitches led to inconsistent alignment of the two materials (the X and Y endstops in a normal printer don't need to be very precise). I solved this by replacing the microswitch endstops with Hall-effect endstops ( http://reprap.org/wiki/Hall-%CE%98http://reprap.org/wiki/Hall-%C... ). Search ebay for 'Hall Endstops' - they are around $10 each. I used bigger trigger magnets than the ones supplied but that was simply for ease of positioning.

I also replaced the Z-axis endstop with a Hall-effect endstop which is completely unrelated to dual x-carriage support but gives a nice improvement in first layer height consistency. [ I'm sure I could design a better Z-axis endstop holder but some Polymorph/Plastimake/InstaMorph/Polycaprolactone (https://en.wikipedia.org/wiki/Polycaprolactonehttps://en.wikipedia.org/wiki/... - great stuff - get some if you don't have some, the uses are endless) and a cable tie is working fine for the moment. ] The endstop already includes a trimpot for fine adjustment of the trigger point.

Pictures here:http://bukobot.com/_detail/bukodualx_endstop1.jpg?id=creating-a-dual-x-carriage-bukobothttp://bukobot.com/_detail/bukodualx_endstop2.jpg?id=creating-a-dual-x-carriage-bukobothttp://bukobot.com/_detail/buk...

Here's another 2 color print I just did: http://www.thingiverse.com/make:42328http://www.thingiverse.com/mak...

By the way the above awesome dragon print is also by tbuser (here: http://www.thingiverse.com/thing:29088)http://www.thingiverse.com/thi...

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I just wanted to add the that my modified X-end design is based on Diego Porqueras' original Bukobot X-end design. I meant to add some attribution in the files but unfortunately forgot before uploading.

I'm so happy someone added this to Marlin.

WOW!!! Most amazing mod to our Bukobot I've ever seen! Great job Rob!