Please keep in mind the differences in spindle register diameters between the Atlas and South Bend lathes. ?
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While they're both are threaded 1 1/2-8, the spindle register diameter on South Bends is 1.510" (IIRC) while the Atlas is 1.500".
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For best accuracy, the fit of the chuck's back plate ON THE REGISTER DIAMETER is very important. ?If you buy a 1 1/2-8 pre-threaded back plate,
almost certainly it will be bored to fit a South Bend spindle. This means you will have .010" clearance at the register diameter. ? This results in the plate being radially located on the spindle threads, and not on the register diameter. ?
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I discovered this on my Jacobs spindle chuck which was bored to fit a South Bend. ?Had to bore out that diameter, press in a ring bushing, and bore it to 1.5005" to properly fit the Atlas spindle.?
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Edit: ?I also have a 9 X 30 South Bend lathe but it has a worn out bed. ?This example's register measures 1.510" ?My Atlas chucks won't thread up to the shoulder due to the larger register diameter. ?If I ever do get it up and running, I plan on turning down the register to 1.500 so I can interchange spindle mounted tooling.
