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garagemark
03-12-2011, 09:57 AM
Since you have talked me into installing the 1/2HP DC drive on my SB9", I have a new question.

Would I be better off just replacing the existing motor with the DC unit in kind, or would I be ahead to eliminate the cone pulleys in the back and make a new pulley for the motor to accept the drive belt directly to the headstock pulley (I use a rubber serpentine belt)?

I have not done Pulley speed calculations.

THX,
Mark

Forrest Addy
03-12-2011, 10:06 AM
A 1/2 HP DC motor only develops 1/2 HP at the rated RPM and input Volts . Halve the RPM by halving the volts (and in AC motors the Hz) and the motor develops half the rated HP and so on in proportion. So if you want stock removal over the entire range of spindle speeds KEEP THE CONE PULLY AND BACK GEAR.

Use the variable speed for in between the cone pulley steps and for light cuts. For heavier cuts use the cone pulley trasnsmission to adjust the speed and the DC drive to refine it in between steps.