Mendel Pulleys

by nophead, published

Mendel Pulleys by nophead Mar 28, 2010


Mendel pulleys that use an M3 grub screw and a captive nut. The advantage over the original is that you only need one small flat on the motor shaft, rather than two full length ones that have to be filed to exactly the right size.

Can be used for all three axes.

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Sorry no I don't have a file for a T2.5 pulley or know how to design one. The teeth on these came from the original Mendel files so they were designed at Bath.

I printed these with a 0.4mm nozzle so I would guess you can print T2.5 with a 0.2mm nozzle and get comparable results.

I'm trying to build a mini-Mendel / Huxley, which look simpler!

Do you have the file for a T2.5 pulley? I'd like to have a go at it... also if I read below that you use smaller nozzle/filament already!

Anyway,how exactly do I re-design it? Is it just making teeth half size and also closer together by half dimension, but keeping the external diameter untouched to not affect the ratio?

Thanks again.


If you are making a Mendel than yes you need to use the belt splitter jig to cut it down to 5mm to fit the machine.

I think you get a little less backlash with a T2.5 belt because T5 doesn't bend as sharply round the pulleys but it is too fine to print pulleys for.

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Mendel Pulleys by nophead is licensed under the GNU - GPL license.

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Ream the holes out to 5mm and 3.5mm, fit the nut and grub screw. File a small flat on the motor shaft where the screw will engage.

I find it best to print three at the same time because it stops the small section getting too hot. If you have a machine that oozes then it may be best to print one at time to avoid strings.


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syncra on Nov 22, 2010 said:

Looks a fantastic alternative to the horrible filing job that I am avoiding from days....

I tried to fit a M3 nut in the hole but it does not fit - shall I use something smaller or just force the nut?


nophead on Nov 22, 2010 said:

M3 nuts fit when I print them, but they are deliberately a tight fit. Maybe your printer setting are making the holes smaller.

If it ABS you can open them up by scraping with a sharp penknife. You can also heat the nut to above the melting point of the plastic and force it in.

bowdidge on May 29, 2010 said:

Worked great, and much easier to use than filing the motor shafts down! I drilled the central holes out so they were a press-fit on the stepper motor shafts, and didn't find it necessary to use a set screw.

casainho on Apr 3, 2010 said:

NopHead, thanks for sharing! -- and that seems a good improvement to original ones from Mendel. I added a link to this ones as an alternative:


lyndondr on Mar 29, 2010 said:

What size nozzle did you use and what were some of the other parameters for this print?

nophead on Mar 29, 2010 said:

0.4mm nozzle extruding 0.375mm filament at 16 mm/s for the outlines and 32 mm/s for the infill. Layer height 0.3mm. ABS at 220C, bed at 120C for the first layer, 100C after that.

rplumley on Mar 28, 2010 said:

I concur with printing multiple small parts at the same time to avoid mushing a hot layer. I believe the new makerbot extruder firmwares have "de-ooze" built in.

jeremyl on Mar 28, 2010 said:

Thank you! This is better then what I was planning to do with mine (drilling out the inside and drilling a small hole for a set screw/grub screw) - the addition of the nut makes perfect sense!

What length screw should be used?

nophead on Mar 28, 2010 said:

Yes I tried tapping ABS and putting a grub screw into it bit it failed very quickly. I think tapping PLA would work better.

The grub screws I used are 6mm M3.