Kevin W Johnson
09-13-2011, 4:24 PM
Well, after struggling to turn a couple bowls that were close to the swing limit on my lathe, i decided a power upgrade was in order. I found a cheap treadmill locally and harvested its "organs". A 2.5HP DC motor, power supply, and speed controller.
I copied the mounting plate for the original motor and made the new plate from aluminum, (2 thicknesses riveted together) as i wanted to keep all the original parts intact. I turned the pulley out of the center of the treadmill flywheel, drilled and tapped for a set screw to secure it when run in reverse. I'd eventually like to make a new pulley, smaller in diameter, which would allow for more motor RPM, while not speeding up the spindle in return. These motors make more power the faster they turn. I don't think it will be an issue for normal turning as the lowest spindle RPM is about 70RPM, well slower than normal turning speed. The fastest is a tick over 4000RPM, so losing some off the top won't hurt either.
I replaced the treadmills console interface with a potentiometer, placed the power switch for the power supply in the original location on the lathe, as well as a "reset" button that allows me to return to my set speed after turning the lathe off without having to turn the potentiometer back to zero and back (common on treadmill speed controllers, it won't start at speed, it has to be set back to zero to start, the reset button accomplishes this zero without turning the pot). I'm still waiting for a switch to arrive so i can add reverse. I might add a cooling fan to the power supply and PWM box, depending on what i monitor when turning bowls. I know penturning won't draw enough current to overheat anything, bowls may be another matter. The aluminum knob for the speed adjustment i turned on the lathe, and still need to make a RPM scale.
I copied the mounting plate for the original motor and made the new plate from aluminum, (2 thicknesses riveted together) as i wanted to keep all the original parts intact. I turned the pulley out of the center of the treadmill flywheel, drilled and tapped for a set screw to secure it when run in reverse. I'd eventually like to make a new pulley, smaller in diameter, which would allow for more motor RPM, while not speeding up the spindle in return. These motors make more power the faster they turn. I don't think it will be an issue for normal turning as the lowest spindle RPM is about 70RPM, well slower than normal turning speed. The fastest is a tick over 4000RPM, so losing some off the top won't hurt either.
I replaced the treadmills console interface with a potentiometer, placed the power switch for the power supply in the original location on the lathe, as well as a "reset" button that allows me to return to my set speed after turning the lathe off without having to turn the potentiometer back to zero and back (common on treadmill speed controllers, it won't start at speed, it has to be set back to zero to start, the reset button accomplishes this zero without turning the pot). I'm still waiting for a switch to arrive so i can add reverse. I might add a cooling fan to the power supply and PWM box, depending on what i monitor when turning bowls. I know penturning won't draw enough current to overheat anything, bowls may be another matter. The aluminum knob for the speed adjustment i turned on the lathe, and still need to make a RPM scale.