Archive for August 24th, 2011

Stepper Motor Shaft Coupler

This simple cylinder connects two NEMA 17 stepper motors together:

Stepper Shaft Coupler

Stepper Shaft Coupler

It’s quick-and-dirty:

  • Cut 2+ inches of 0.375 drill rod, face both ends
  • Drill #8 = 0.199 inch = 5.06 mm (because #9 = 0.196 inch = 4.98 mm is a bit too snug)
  • Cross-drill #41 in the Sherline (because #43 makes for stiff tapping)
  • Tap 4-40 for the setscrews
  • File off rough edges, run #8 drill through the bore to clean out tapping chips &c

Now, you probably don’t want to do this in real life, because you want a coupler with a bit of compliance to soak up the inevitable misalignment and dampen the mechanical resonances.