I was recently given a 1 hp, 3,500 rpm, 120v motor and thought it might be worth trying it in my Atlas 618. To get the speed back down to factory specifications I calculated the required pulley sizes, modeled them (using Revit or Sketchup) based on mvagusta's great drawings (adding some thickness to the sides) then 3D printed them, which took nearly two days for the large pulley. Today I ran it through all the pulleys, cutting aluminum and carbon steel and it all worked great! Depth of cut was equal to what I was getting using back-gear (I think it was 0.025" in carbon steel and 0.040" in aluminum) The couple times I tried taking too deep of a cut the belt simply slipped, which was what I hoped would happen. The rpm's measured about 10% slower than factory specifications which is probably better than them being too fast. Very excited!
