Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Prusa i3 Improved for laser cut

by twelvepro, published

Prusa i3 Improved for laser cut by twelvepro Jan 1, 2013


We found latest Prusa i3 printer design, the one Josef Prusa showed at Makerfaire this year in New York, for its elegant simplicity, but hinge like connection between Y axis assembly and frame needed improvement, in our opinion.

Using CAD software we reworked Prusa i3 design:

- Laser cut frame was stiffen by adding two angle members connected to the rear side of Y axis assembly.

- Original, printed Z Axis mounting parts proven to be easy to break, which is why we replaced them with stronger laser cut parts.

- We did not like loose ends on Z Axis lead screw (similar to Printrbot design), therefore we added miniature flanged ball bearing on each side, to support lead screws on the top.

- All printed plastic parts were slightly changed, we felt that we should give them additional strength and better cosmetic appearance.

- Y axis assembly can be removed and installed back in a minute. Convenient for transportation or shipment.

- Dimensions and axis travels of original Prusa i3 preserved.
Test print here:


More Pictures here:

Recent Comments

view all

The threaded rods are 8mm

Is this made for m8 or m10 rods?

Yes you can use plastic parts from Prusa i3 design

More from 3D Printers

view more

Liked By

view all


Prusa i3 Improved for laser cut by twelvepro is licensed under the GNU - GPL license.

Give a Shout Out

If you print this Thing and display it in public proudly give attribution by printing and displaying this tag. Print Thing Tag


You will need (for now we using mixed SAE and metric parts):

Smoth Rods (8mm)
X-Axis: 2 x 15"
Y-Axis: 2 x 16"
Z-Axis: 2 x 12.5"
* If you purchase 36" (1M) smoth rods, you will need 3 of them
Threded Rods:

3 x 8.5"
1 x 12"
2 x 17.5" (18")
* it will take total 2 x 36" (1m)

5 mm for Z- Axis: 2 x 12"

We stil working on instructions and complete BOM.
Kit available for purchase.

Happy New Year to all!!!


You must be logged in to post a comment.

Rapman711 on Jul 15, 2014 said:

Is this made for m8 or m10 rods?

LeChuck71 on Jul 17, 2014 said:

The threaded rods are 8mm

twelvepro on Jun 9, 2014 said:

Yes you can use plastic parts from Prusa i3 design

rancor1223 on Jun 9, 2014 said:

Would it be possible to use regular Prusa I3 printed parts with this?

draj on May 13, 2014 said:

The .dxf file seems to be scaled 2:1. Pay attention, it may need some work before ordering it from a laser/water cutting company

LeChuck71 on Apr 29, 2014 said:

Any recommendation for an extruder? I got all files waterjet cut and parts ready to go, I am just not sure which extruder to attach

vipseixas on May 5, 2014 said:
vipseixas on May 5, 2014 said:
yoursstreuli on Mar 25, 2014 said:

BOM seems to be not ready yet?

ralpha on Mar 11, 2014 said:

Hello fellows,

I'm planning to use this model to build my Prusa i3.
I just need to be sure about the size of the rods:

Smooth Rods (8mm)
X-Axis: 2 x 381mm
Y-Axis: 2 x 406mm
Z-Axis: 2 x 318mm

Threded Rods:
5 x 406mm
3 x 216mm
1 x 305mm
2 x 445mm or 457mm (?)
5 mm for Z- Axis: 2 x 305mm

Can someone please help me?
I just need this measurements in millimeters.

Thanks so much!

vipseixas on Mar 21, 2014 said:

I used X:385 / Y:405 / Z:320 for the smooths and they are only a few mm in excess (6mm for Z, 5mm for X and doesn't matter for Y). There is no problem exceeding a few mm from the exact length so I rounded up the lengths.

For the threaded I used 3 x 210 / 1 x 280 / 2 x 440 for the Y base (8mm) and 2 x 310 for Z (5mm), but 305mm would do fine. You only need 8 threaded rods to assemble it.

yabadabadu on Jan 19, 2014 said:

Where is the Bill of materials? Still working on it?

gidio on Jan 17, 2014 said:

Where can I buy plastic needed?

antpgomes on Jan 15, 2014 said:

would this work with 1/4" wood?

twelvepro on Jan 15, 2014 said:

Yes, it will work. We use it with no problems.

Kentucky13 on Jan 10, 2014 said:

Where can I buy plastic parts for this model?

Mithrandir on Jan 10, 2014 said:

Before I built my printer I got my parts printed by BusyBotz at www.busybotz.com

digitalw00t on Dec 9, 2013 said:

So which bed did everyone go with? Has anyone designed a 3 point leveling system for this variant?

sgraber on Dec 9, 2013 said:

You could probably grab the one from here: https://github.com/sgraber/Gra... or here: https://github.com/sgraber/Gra... as they are both setup for 3 or 4 point leveling.

Oliv4945 on Nov 22, 2013 said:

Hi. Great design !
I am wondering to do or buy one, but why did you use metric and imperial ? Could we use only metric ?


twelvepro on Jan 15, 2014 said:

Yes, you can do it...

RickM on Nov 4, 2013 said:

Just curious. Has anyone else noticed, or experienced issues with a potential flaw with this, and most i3 variations (seemingly including the original). Where the y-bed attaches to the main frame, there's nothing really holding it in. The bed simply sits in the two grooves for the threaded rods.

If your surface isn't absolutely perfect, you'll never get a flat bed. Really those groves in the frame need changing for simple holes. That way even if one corner wasn't level, it shouldn't cause so much of an issue as right now the bed will just sit slightly higher up thanks to the groove.

You can tighten bolts on either side of the groove as much as you like, however having only been using my new i3 for a few weeks have had to re-tighten them twice, and found minor variations in bed level each time.

Curious to know if anyone else has mentioned this issue, and if there is in face a better way of keeping the bed firmly attached to the main frame. Maybe some sort of extra (printed) mounts that attach under the bed?

twelvepro on Nov 4, 2013 said:

I would suggest use nylon luck nut instead of regular nut. When you mount heated bed, you should use springs (1 for each corner). Some heated beds are bended from corners to the center, then best choice would be a glass on top of it.

Tanga on Sep 20, 2013 said:

What thickness material is this designed for?

twelvepro on Sep 20, 2013 said:

It was designed for 6mm material thickness.

MijailR on Aug 30, 2013 said:

What is the size of the table for laser cut?

twelvepro on Sep 20, 2013 said:

It is made based on MK2 heated bed sizes and have mounted holes.

Mxdbag on May 23, 2013 said:

WARNING!!! DO NOT BUY FROM TWELVEPRO! I placed an order with twelvepro from Australia. All they sent me was a tracking number for a parcel sent to Switzerland??? They will not reply to any of my emails. Very disreputable company!

lamerhouse on May 24, 2013 said:

Mxdbag said: WARNING!!! DO NOT BUY FROM TWELVEPRO! I placed an order with twelvepro from Australia. All they sent me was a tracking number for a parcel sent to Switzerland??? They will not reply to any of my emails. Very disreputable company!

Seudotron on May 11, 2013 said:

Hello, what extruder are you using?, Where did you find it?

talleres on May 9, 2013 said:

at this moment is the buddasch and x-carriage compatibles?

bernabap on Apr 1, 2013 said:

Just to help the next guy I am posting here that this latest files X-Carriage and buddasch they are not compatible. Holes do not match, and some other problems. Do not waste your time printing them.

thainfamousnate on Mar 21, 2013 said:

the stl files are missing the extruder/hot end carriage!!

thainfamousnate on Mar 21, 2013 said:

i bought these plastic parts on ebay, but your stl files are missing a part. wheres the hot end/extruder mount to lm8uu printed part?

airheli1201 on Feb 28, 2013 said:

would it be possible to cut this with a cnc? My friend only has a cnc router.

twelvepro on Feb 28, 2013 said:

You can try use our .dxf file or you can order it at:

effy on Jan 30, 2013 said:

Are the i2 parts useable to make the i3? i.o. can I upgrade?

twelvepro on Feb 28, 2013 said:

You can use electronics, heated bed LM8UUs, extruder, but all plastic parts and frame was changed.

green_domingo on Jan 9, 2013 said:

Where are X-carriage file?

maxoutny on Jan 4, 2013 said:


twelvepro on Jan 4, 2013 said:

These are ALL source files representing current stage of development, which is - without extruder. We were going to complete it with extruder and publish it, but since you demanded it with uppercase - here they are.

For assembly instructions, please consult with https://github.com/josefprusa/...
Attached photos and CG images might help as visual clues.

Assembly diagrams and instructions will be published as soon as they are ready.

BOM has all you need, except for extruder parts. All parts numbers are included.
Shaft and threaded rod are given with their exact length in millimetres.

BOM is not structured by assembly, just raw data exported by CAD software.

Thickness of material for laser cut frame - 0.25" or 6mm. You can probably use 0.22" as well.

Good luck building!

We will publish more as soon as have something else to share.
We are open for questions or suggestions.

scotty1024 on Jan 4, 2013 said:

I've paid, I've gotten less than what I expected quality laser cut parts and need the DXF files to get the parts re-cut properly. How do I escalate this under the GPL?

rp_one_labs on Jan 4, 2013 said:

Submit your claim in GPL court, I guess. I sent all source files to Twelvepro to publish, it will be done it half an hour. What are your issues with the frame, by the way? I assembled three printers and barely find areas of improvement. I think you just using publicity on Thingiverse to resolve something with Alex which is not related to the printer design. Please, use other means of communications to do it.

prusajr on Jan 4, 2013 said:


twelvepro on Jan 4, 2013 said:

It is coming today....
I am glad you are interesting. Your opinion is very important for us.

scotty1024 on Jan 3, 2013 said:

I'm not kidding around here: where are the laser cut files for the laser cut kit I purchased? Apparently, as with the printed parts I bought, I need to have the parts re-made and need the files to do so. You appear to have alignment issues with your laser cutter as dims don't match from hole to hole and hole placement is off so parts don't fit cleanly.
I like the design but need it cut by someone that has their laser dialed in correctly (MakerFarm).

rp_one_labs on Jan 2, 2013 said:

Alex is out of reach at the moment and I could not take over this thing, however, I posted all necessary STL files here:


Twelvepro will eventually repost STLs here as well as BOM and DXFs. Eventually means - when we feel like we are ready to post them, not when you guys feel like we need to. Don't push.

scotty1024 on Jan 2, 2013 said:

I used Buy it Now on eBay and thus paid full price for both a laser cut MDF set and a printed parts set. Under the GPL I am entitled to the design files.

I've asked nicely by email and now I am asking publicly.

I want the files for the parts I have. I am over joyed you all are continuing to refine the design but the moment you took my money you hit Rev X. You are supposed to be able to give me Rev X to match the parts I have.

rp_one_labs on Jan 2, 2013 said:

Use thing


To fix Z Shafts on the top.

scotty1024 on Jan 2, 2013 said:

I've printed all posted files and compared them to Twelvepro's parts. Twelvepro really needs to work on dialing in their 3D printer. I hope that doesn't mean I'm going to be working hard to get this Prusa i3 working well after I struggle to finish it. :-(

I would appreciate it if you all would post the rest of the files so I can print them properly as well. (and I get ready to rebuild this baby one more time...)

Pictures are up on Twitter.

Diamond Age calls it Banana, I call it Sunshine! I love this PLA!

Two last feedbacks before bed... the Y belt clamp has some serious bite to it. I'm very convinced one wouldn't even need tie wraps. That said, you can't tension the belt once it's in the clamp. You have to pull the belt back out and force it back in. Maintaining tension whilst forcing the belt sideways into the clamp is, ummm: challenging.

I was hoping to use the third hole in an RRD MK2A hot bed. Have you all thought about moving the horizontal bars out closer to the edge so a "third hole" for a three hole bed level could be popped in? You could still leave in the normal four holes and add the third hole.

Anonymous on Jan 3, 2013 said:

Is this your support forum for your purchase?

scotty1024 on Jan 2, 2013 said:

Almost forgot to mention...

You might want to check the dim's on the 5mm bearing on both of the top laser cut pieces. One 5mm bearing went in nice and snug, the other went in loose, not sloppy loose but not snug either.

And religious holy wars aside: the constrained Z threaded rods work damn well so far. So if I'm going to hell for tying them down I'm going there on biscuit wheels baby!

I would also love to hear about what nuts I need to be using for the Z threaded rods on the X ends... I've cobbled that together for now as well.

drandolph on Jan 2, 2013 said:

Looks great I'm excited. I can't wait for the laser cut files. My laser cutter is begging to get started on building one. I just finished the Prusa Air 2 and I have no problem gutting it for some parts to build this out.

scotty1024 on Jan 2, 2013 said:

Actually you do have a problem with your Prusa Air 2 printing out the parts: they aren't posted. You can't build one with the parts posted combined with the original Prusa i3 parts. They changed the Y belt clip and haven't posted it yet.

scotty1024 on Jan 2, 2013 said:

Well good news and bad news on the X end motor. You can see the pictures on my Twitter (scotty1024). Part printed great and bonded very well with Diamond Age Banana on my PrintrBot Jr (my current top dog print quality 3D printer).

Which means the bad news is Alex needs to buy a PrintrBot Jr. :-)

Actually I suspect Alex didn't use the official Prusa i3 parts extrusion settings: .3mm layer height and 220% extrusion width. From my experience those are pretty unusual settings.

The bad news for me? I guess I've gotta rebuild this thing one more time. :-)

scotty1024 on Jan 2, 2013 said:

I don't know if it was Twelvepro's printing or inherent to the design but the outer side of the diamond pattern, right there at the peak of the diamond broke in the X end motor part Twelvepro sent me. The X carriage parts in general made many creaks and pops when inserting the rods so I'm not 100% convinced they were bonded well.

Now that I have the STL I will have to try printing my own X motor end and see how well my PrintrBot Jr bonds it.

scotty1024 on Jan 2, 2013 said:

The belt clamp is missing for the X carriage and is not compatible with the original Prusa i3 clamp. I purchased and Express Mailed a printed parts kit and didn't get the needed clamp either. :-(

Also, their laser cut Y carriage is incompatible with Prusa i3 Y belt clip. Fortunately they included that part but it is NOT posted here. The Prusa i3 part has 3 screw holes in a T pattern and their new part has two inline holes. Completely incompatible.

I am using #10 x 24 threaded rod. I bought a 24" piece at Home Depot and they sawed it in half for me (they were also sawing up 3 36" rods for a Rostock mini).

However the only #10 nut Home Depot had is not fitting in their nut trap. :-(

I have mine up and moving with X Y and Z calibrated but am puzzling over extruder options. I am sure Prusa is patting himself on the back but as far as I can tell his new removable extruder plate is a complete pain in the ass.

scotty1024 on Jan 2, 2013 said:

The Z rods are not tightly held in the laser cut frame kit I received Friday. I had to zip tie the rods to keep them from coming out. :-(

My build with Prusa i3 parts I printed (Alex assured me Friday I could use i3 printed parts) and then re-build with the parts I bought is all up on my Twitter: scotty1024.

A promising design but for now it is unbuildable from any publicly posted parts or even from parts bought from them. I hacked around the missing cable clamp but I have limited X range of motion due to zip tying the belt and that kludge running into the X idler bearings. :-(

I wanna show my new baby off locally but she's ugly right now. :-(

Which is frustrating because the laser cut frame makes the Z axis a WOW! (well, once you zip tie the Z rods) I used GT 2 belts and cables (Trinity Labs) and oh baby she moves nice. (until the zip tie his the idler bearing)

twelvepro on Jan 2, 2013 said:

More Pictures can be found here:

rp_one_labs on Jan 1, 2013 said:

Laser cut DXF files, all STLs and BOM for this adaptation will be released as soon as we finalize all changes based on feedback from users. We are also working on our adaptation of Joseph Prusa PG35L extruder which will be part of this design. So, as soon as we ready, you guys will get it. Our work was based on open source hardware and it is open source hardware.

karandex on Jan 1, 2013 said:

the carriage is changed in jo-final ver which is for plate type i3

rp_one_labs on Jan 1, 2013 said:

While not constraining Z axis lead screw certainly makes
sense in many cases, in this particular design it does not introduce any measurable
or noticeable wobbling or undesired shift between layers. Lead screw is
relatively thin and flexible (M5) while Z axis shafts mounted on the frame are
quite rigid. That is why I decided to introduce an option to constraint it on
the top with flanged MF105ZZ ball bearing, which makes, in my opinion, slightly
cleaner design (I am working with twelvero on this Prusa i3 adaptation). Those
of you guys, who does not like constrained Z axis may just not install ball
bearing on the top. Rigidity of the
frame in this particular design
contributes much to the printing quality, and that was determined by our
tests, while Z axis lead screws are not really an issue at all. But like I
said, there is no point for holly war, just don’t install ball bearing on the
top, if that is what you don’t like.

Happy New Year to everybody!

sgraber on Jan 1, 2013 said:

Will you or Twelvepro release the laser cut files? If so, when / where?

weldmaster80 on Jan 1, 2013 said:

just bought this design from you am eager to try it out, will post and let eveyone know how it works

twelvepro on Jan 4, 2013 said:

Thank you!

sgraber on Jan 1, 2013 said:

FYI I'm in the last stages of getting my own laser cut files out there for the i3 frame. When complete, I will release them both on Github and Thingiverse. I'm working with the SeeMeCNC guys on it.

Currently I have mods made for 3/8" acrylic and I'll release one for wood like the Twelvepro one soon. My version uses Josef Prusa's exact same frame.dxf and just adds laser cut slots and screw holes and adds two additional triangular braces for rigidity for more flexible material like wood and acrylic which tie into the back y-axis threaded rod (similar to the Twelvepro ones). All existing i3 parts on Prusa's git repository will work just fine with it:



One comment: the z-axis mounting parts were too weak??? I printed mine at 240C, 3 shells, 40% infill in black ABS and they're not weak at all. Color me confused!

wjsteele on Jan 1, 2013 said:

Actually, for those of you worried about constrained z screws, you can fix them as long as the captured nuts are not tightly captured. The smooth rods will keep the z axis in place.

on Jan 1, 2013 said:

So we now need a fix for a "fix" that didn't fix anything, but brings up new problems? Why not leave the Z-leadscrews unconstrained in the first place?

thantik on Jan 1, 2013 said:

Holy crap have you guys learned nothing? Do _not_ constrain the Z threaded rods! They are loose for a reason!

karandex on Jan 1, 2013 said:

where are lasercut files?

twelvepro on Jan 4, 2013 said:

It is still under development, but based on many requests


Thank you all and sorry for delay.

wersy on Jan 1, 2013 said:

Somehow it reminds me to the Mendel90 ;-)

SystemsGuy on Jan 1, 2013 said:

I still remember Nophead's comments when the Prusa was released! :P Full circle!

Spiritdude on Jan 1, 2013 said:

And MendelMax 2.0 .. they become all very alike.

JelleAtProtospace on Jan 1, 2013 said:

Happy new year to you as well!
Please reconsider your fixed Z leadscrews. It may look less nice, but you will get Z-wobble if you over-constrain them like you do. The thing you need to realise is that all leadscrews (and couplers!)are bent slightly. Clamping them at two points leaves room for the leadscrew to move in XY. If you don't, this XY movement will translate in a XY force on the XZ carriage, leaving a small wobble in your prints.

Also: threaded rod is not a good material for leadscrews: it has too little pitch (so fast Z movement becomes impossible) and the nut will fail within a years time.