I happen to be in the midst of this project at the moment. My
analysis has been this:
The torque requirement all depends on the metal and how much of a
reduction per pass one choses to make. The common hand mills with
ratios of 3:1 and 4:1 seem to work out with about 30 foot-pounds on
The speed should be “comfortable” to allow you to feed and pickup
without feeling rushed and out of control, 5 to 10 rpm seems
A motorized unit is on the market listing; 2 1/2 HP 110 V
yielding 5 to 40 rpm. My guess is that a major part of the speed
control is by voltage reduction and consequent loss of torque. A
postor who is more engineering educated than I can surely educate all
of us, but my gut tells me that 2 1/2 HP at 5 rpm is way beyond
I’m trying the following:
A. HP mini mill with 3:1 ratio and a 12 inch pulley.
B. A surplus tread-mill DC motor rated at 3/4 HP with a 1 1/2 inch
C. A surplus pulse-width modulated DC power supply yielding broad
range motor speed control with essentially full torque.
- Parts cost thus far appear to be, mill + about $60.00.
I’ll be most interested in other comments and especially
criticisms–and I"ll let you know what happens!