SAE Mendel

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SAE Mendel

Release status: Experimental

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Building a Mendel entirely from SAE hardware/fasteners.
CAD Models
External Link


An attempt to build a Mendel from 100% SAE components. In Canada (and USA I hear) SAE parts are not only MUCH easier to find, but are much less expensive as well... This should help reduce the price, and make sourcing parts a lot less painful for those of us on this side of the pond.

I've begun my build, and I'll be making basic jot notes here as I go... Once done, I'll photograph, and update a BOM for the SAE build, so that others can recreate my results.


  • Using 8-32 screws instead of M4 (diameter 4 mm --> 4.17 mm)
  • Using 5/16 inch (7.938 mm) smooth rod instead of 8 mm smooth rod -- the difference is about half the thickness of a sheet of paper; you probably won't even notice the difference.
  • Using 5/16" threaded rod instead of M8 threaded rod (diameter 8 mm --> 7.94 mm; pitch 1.25 mm --> 1.41 mm)
  • Using 6-32 screws instead of M3 (diameter 3 mm --> 3.51 mm)
  • Bearings from Ultimachine that I got are just a hair too small for the 8-32 screws (like .05mm) so I had to mount them in my drill press and file down the threads by a hair. nuts still work fine, and now bearings fit, but going forward might want to get different bearings.
  • SAE nuts are a little bigger than metric. Trapped nut holes are a pain. I can make the 6-32 nuts fit, but not 8-32. So that means dropping the screw sizes for those spots as well... We will see if this causes problems. The fit is still tight but it works.
  • SAE 8-32 washers are higher diameter than M4, so they are too big when put against a bearing (touches outside of bearing). So need to use 6-32 washers and they work perfectly. (note 6-32 washers will only fit on an 8-32 screw after the filing trick I mentioned above)

Imperial Reprap SAE

this page is the compiled location of metric to imperial or SAE conversions.

the full list of metric parts for a mendel is at this link Mendel-m4-assembly-data-sheet.ods

a complete SAE prusa is attached here SAE Prusa Mendel.

See also