Ok, I hear alot of people here talking about building a spindle, and was wondering what size motor they would be using. I did some calculations and found that I would need about 1/3 hp to cut 1 cubic inch of material per minute. At a depth of cut of .05" with a 1/4" endmill that would give me 80ipm feed. Sounds a bit fast. Searched on ebay and found these Aemtech dc motors. Has anyone used these for their spindle?? I see these used as servos on some projects. Looks like a well built motor.
I believe that at 900 RPM they are a bit slow for spindles. If the motor's pulley was larger then the spindles then you could increase the speed, but the torque would be reduced considerably.