Adding a Heatsink and Fan to your 3D Printers NEMA 17 Extruder Stepper Motor 3

The first thing I noticed about my new MakerFarm prusa i3 was that the NEMA 17 extruder stepper motor was getting very hot.  So I ordered a 40mm x 40mm heatsink and 40mm x 40mm x 10mm 12V fan from  When I attempted to install the heatsink and fan I realized I needed much longer machine screws.  They needed to be 25mm longer then the stock NEMA 17 screw.  So I started looking for m3 75mm screws.  McMaster Carr only went up to 60mm, Fastenal did not carry them either.  The only place I could find the proper length screw was a German R/C car site that looked a little out dated.  I could not believe the screws were so hard to find.  One day I was telling my father this dilemma and said “why don’t you just make them from threaded rod?”.  Damn good idea Dad!

I ordered a m3 threaded rod from McMaster Carr.  Threaded on some nuts then cut it into 72mm lengths.


Then I threaded 2 of the rods into the extruder stepper motor.  A nut was used to tighten up against the motor.


Now with the studs extended I put on some heatsink compound then slid on the heatsink and fan a washer and lock nut.


You may notice I went heatsink crazy and added some passive heatsinks to the three exposed sides of the stepper.  All I can say is that my extruder stepper runs nice and cool now.

3 thoughts on “Adding a Heatsink and Fan to your 3D Printers NEMA 17 Extruder Stepper Motor

  1. Reply chris meyers Jul 30,2014 8:05 pm

    What exact threaded rod did you use from McMaster ? Can you post a link?


    • Reply admin Jul 31,2014 1:25 am

      Metric 18-8 Stainless Steel Threaded Rod, M3 Size, 1-Meter Length, 0.50 mm Pitch
      McMaster part # 90024A040

  2. Reply chris meyers Jul 31,2014 1:53 pm


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