I' m about to put a jackshaft-mounted pair of pulleys on a drill press for lower speeds. Does it matter/is there a best place to put the shaft? I'm trying to figure out if it is offset on the drive side will the forces on the bearing be more balanced.
The commercial wide-range drill presses have two short belts with three cone pulleys, the center one is usually pivoted eccentrically on the center post to provide for tightening both at once. The offset doesn't seem to give undue wear on the bearings, but I've not seen one that's had 60 years of wear yet. How low a speed do you want? Lowest I've seen with the above arrangement was like 40 rpm. Has been several articles in various model-making and home shop mags about retrofitting a 5 speed press to that arrangement in the past, some even going so far as to machine the v-belt cone pulley for the center.
Stan
I saw a setup for speed reduction where the main motor had a double shaft, with a pulley on the bottom shaft, belted to another motor mounted to the column at a decent reduction. Just so long as one doesn't apply power to both motors at the same time, seems like a fairly easy solution.
Jon
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