Timing Belt Y GT2, Printrbot Simple V2

by iamjonlawrence, published

Timing Belt Y GT2, Printrbot Simple V2 by iamjonlawrence Dec 2, 2013


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This will work for both V2 designs (with & w/o string tension). Included is a fan mount to be compatible with aluminum extruder upgrade.

In response to multiple requests I have developed this GT2 timing belt conversion for the Y axis of the Printrbot Simple. This thing is similar to my original http://www.thingiverse.com/thing:180146

Differences are:

  • Use GT2 belt & pulley instead of the MXL
  • Use 608 Bearings instead of R2
  • Requires some modification of the wood Y axis part for the pulley to pass thru. Only needs modification for assembly purposes. After assembly the pulley should clear the stock slot during operation.


  • GT2 tooth form
  • Common 608 Bearings


  • Requires some modification of the stock wood parts
  • Small motor shaft engagement distance. Limit belt tension, otherwise risk pulley not running concentric to shaft and damaging pulley.

For anybody having trouble printing these parts I have uploaded a 2014 version to Shapeways if you would like to order them online. http://shpws.me/rbxt

This is marked as a work in progress. If you have a success (or failure) please let me know. Feedback is greatly appreciated.


  • Shortened motor plate by 2mm
  • Added notch for wrench access to pulley
  • Reduced length of pilot for bearings on motor plate, added pilot for bearings to tie bar. This should allow the bearings to be installed/removed with the pulley in place.


  • Updated the Belt End Block Rear to accommodate bot the V2 versions. One mounting hole for the version without the Printrbot string tension device and one mounting hole for the current version that includes the string tension device.

  • 2014-01-06: Updated BeltEndBlockGT2Rear for better alignment on Simple model w/String Tension.

  • 2014-01-29: Added BeltEndBlockGT2Front-Fan for those using the early 2014 version Simple with the fan mounted on the side. This will replace the previous BeltEndBlockGT2Front. If your machine has the fan mount included in the Y plate, see next update:

  • 2014-02-25: Added BeltEndBlockGT2Front-2014 for the post-Jan. 15, 2014 machines that have the fan mounting included in the Y plate.

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Have some trouble after 1 year with axis. You can see it here http://www.thingiverse.com/thing:1079446 on detail with smile.
I think not enought tension in front part, but i use PLA this may be a problem.

Printrbot Simple 2014 spool holder (bearing 625z)
by Sneq

I did this mod, and the related X axis mod to my early 2014 Simple. I am getting slip in the Y axis- print shift. I think that the GT2 gear is slipping on the y axis motor shaft. I am thinking to upgrade to the larger Nema 17 motor (with it's longer shaft, which is also D shaped) and hopefully eliminate this problem, unless there is a hack anyone could recommend?

Yes, replace the small y axis motor with a larger one. You will find a huge performance increase. The little motor skips steps like crazy and is not suited to the application.

Any help on what "Nema 17" motor should be sourced? Haven't had to choose a stepper before. I see them spec'd by weight, "mm" (screw hole distance? body? shaft?), torque, amperage, etc.

An Amazon or eBay link to a motor that doesn't skip and has the right length and type of shaft (and connector?) would be the awesome...

thank you! I am also just looking at your y-axis sag fix too! I will post my build pics soon!

There may be an obvious answer to this somewhere that I just haven't found yet, but is there a list of extra parts you need to install this somewhere? I keep needing to go to the hardware store and buy long screws. Also, is there an installation guide somewhere?
Edit: Found it. I was just having problems seeing the pictures in the mobile version, but everything I need to know is in there.

I can't figure out how to attach the rear belt end block, though. I've got the version that had a belt tensioner.

I built and installed this over the weekend. The 608 bearings are almost meshing with the pulley, which is causing it to periodically jam. It looks like the belt want to walk out to the edge and then get stuck between the rim of the pulley and the bearing. It's almost like the slots in the tension pieces are too far from the wood. I tried trimming the belt, but that didn't help. I do have a work around - I happened to have one 688 bearing that has the same inner diameter, but a smaller outer diameter. I put it on the back (where most of the jamming is occurring - towards the tensioner) and was able to complete a 1 hour print with no problems. But I'm worried that the jamming may happen on the front.

Anyone else have this problem?

I just finished a make of this, some things that you should know. You will need M3-20mm screws to replace your M3-14mm that you are pulling out for the upgrade. If you are using the printrbot Xl/Tower upgrade you will probably hear some nasty vibration, that is you Z-Screw bouncing off the side of the hole at the top.

Yes, the screw change is called out on the drawing item "F"
This upgrade does not touch the Z screw, can you explain the vibration you are getting?

Anyway you can modify the motor plate so it pushes the print arm out a few more mm, that way those of us who have the Tower/XL Tower don't have to go cutting chunks out of our wood parts to avoid the fan area from bashing the edge of the side panel :) Thanks

I am note clear of what the problem is exactly. On 2014-02-25 I added "BeltEndBlockGT2Front-2014" which will eliminate the need to add the big fan block that hits the XL Tower.

i did this converstion a few nights ago and just relized that my y travel is off now if i have a 15mm travel it only does 12.678mm and ideas how to fix this problem

After you installed the new drive pulley, did you re-calibrate your "Steps per mm"? For the GT2 - 20 tooth pulley it should be right around 80 steps/mm.

i have no idea how to do that all i do now is put a line of code in the g code saying go 98mm on every print its a 16 tooth im at work as soon as im home ill look into it further but im getting nice prints if i print something 50 x 50 x 10 it with be like 50.3 x 50.6 x 9.8 but now i have no slips at all and i am very pleased

This is fantastic, very excited to get moving on this. It'll be the first modification to my 2014 Simple- can you make any recommendations on infill density/patterns for these parts? I'm using PLA with Repetier, if that affects anything. Thank you!

First the non-helpful, but real answer: That depends on your filament, layer adhesion, print quality, etc.
Now the more helpful answer: Assuming you have good layer adhesion and your filament is typical and not extremely brittle. I print with 3 perimeter loops, 1.2mm skin thickness and around 20% octagonal infill and have had no problems.

="thingiverse-3b64e27c9d196fb1caf81649e53290c8:disqus" href="http://disqus.com/thingiverse-3b64e27c9d196fb1caf81649e53290c8/iamjonlawrence Thank you so much for putting so much time and effort into these models and the plans pdf is a great help thank you so much

Just uploaded a version for the 2014 Simple to Shapeways if you are really struggling in getting it printed. Not the most economical option, but I thought I would put out a last resort for those who are interested. The parts have been modified to be printed efficiently on the SLS machines over there. Below is a link.

This works absolutely great! It does seem to be incompatible with the Y Sag fix at http://www.thingiverse.com/thing:99364http://www.thingiverse.com/thi.... Any ideas?

Printrbot Simple Anti Y Sag
by JohnSL

The motor shaft was the hard part. I would recommend my no-sag Y axis mod: http://www.thingiverse.com/thing:242185http://www.thingiverse.com/thi... if you are having trouble with the sag.

Printrbot Simple, 300mm Y Axis-No Sag!

I am still using the Y-sag fix I mentioned and have managed to solve the issue by printing my own shaft extender, extending the motor plate and creating a new bearing tie that allows the pulley to stick through it partially. It seems to work great, but I might ask someone with a lathe to make the shaft extender in aluminium for extra strength...

Check the Printrbottalk thread. I did a pretty big post there. For some reason i can only post here using thingiverse's mobile app.

Howdy - just finished printing the parts for the Y-Axis last night and find that there might possibly be a misaligned hole in BeltEndBlockGT2Front-Fan.STL - the mounting hole is aligned with the bottom Y-axis rod - where in my bot the hole is slightly above - practically parallel with the top of the bottom Y-axis rod. Beautiful designs!

I am not sure how the belt will line up, but I have uploaded a BeltEndBlockGT2Front-Fan-B.STL that may work for you.

I am getting a whole lot of vibration from the printer. I did the x axis and it works fine, but for some reason in the y there is a lot of noise from the vibration. It's really bad. Anybody else have the same problem or know what is wrong? I have already looked all over the printer and can't find out why it is vibrating so bad. I believe bearing/motor mount for the y but still unsure exactly what and how to solve it.

I'm having the same issue. Did you ever resolve it?

I just finished printing this out and a question on assembling it came to mind? Is this going to work with the fan and aluminum extruder in the 2014 version of the Simple? It seems like it is the best option for belt use, but I am waiting for my aluminum extruder upgrade and it looks like it uses the 2 front bolts that the front "belt end block" would also need. It appears that the fan would be in the way and the new wood mount would push this belt part out a minimum of 6mm out of alignment, if it did fit.
I don't think the current design and the aluminum extruder upgrade would be compatible. Maybe design a piece that would mount on the string anchor screw and the frame screw above that would work?

I do not have the aluminum extruder, so I cannot say for sure. From looking at the pictures online, it looks like you can mount the fan on top of the belt mount block like a GT2 belt end block sandwich. This would move the fan outboard a bit more, but should still work.
You can look at the MXL design to use the string tension bolt location. On the GT2 / 608 bearing version the 608 bearings are too big and actually overlap that screw mounting hole.

Got my new aluminum extruder, Printed out you front belt fix works perfect. I'll toss a picture up on "I made one" so that you can see it. Slic3r did do a weird thing with the inside sloped edge where it meets the outside wall. it may have been too thin to print, so it didn't even try. see if I can post that picture too. it shows the final print as well as the slic3r screen showing the missing outer wall.

I have uploaded a new file that thickens that wall. Should resolve the issue.

I really like your design. Think it is the best option. So when I get my new parts from printrbot, I think I will combine their fan plate to your belt end block. Shouldn't be too hard to add a 6mm fan plate to your existing belt end block once I have the actual dimensions.
I really wanted to bring it to your attention since the upgrade has been selling out (on amazon especially), so some people already using your belt kit might be stuck for a solution if they try to upgrade their extruders. I'd be happy to pass along the dimensions when I get them.

The DXF is available. I threw the fan bolt pattern on the existing end block and uploaded. You will need longer screws as the fan sits 8mm further back. Check it out and let me know if it works for you.

Got my new aluminum extruder, Printed out you front belt fix works perfect. I'll toss a picture up on "I made one" so that you can see it. Slic3r did do a weird thing with the inside sloped edge where it meets the outside wall. it may have been too thin to print, so it didn't even try. see if I can post that picture too. it shows the final print as well as the slic3r screen showing the missing outer wall.

All i can say is thankyou! This is amazing just ordered all the parts and printed out my parts last night.

btw, 608 bearings are skateboard bearings (or inversely). ~$15 for a set of 8...

Rev B works perfectly! thanks for the rapid response!