South bend lathe spindle bearing adjustment DO NOT DO THIS

I have done enough machinery restorations to begin to think I know what I'm doing ...

I have never restored a south bend lathe before. I have a 13" south bend lathe. I wanted to make sure that the wicks inside the headstock were feeding oil properly and were not all hard and gummed up.

I proceed to remove the piping plugs on both spindle bearings, removed all bearing expander screws, and then took off the four bolts holding on the front and rear bearing caps. Both caps could not be removed by hand, so I got a hard rubber mallet to lightly whack down on both caps. Then I got a brass bar of the right size to insert in one of the bearing cap bolt holes to wiggle each cap off. The front bearing cap came off with no problem.

The rear bearing cap was a little more stubborn. I started to jiggle the brass bar with a little more vigor. Still stuck. So I gave a little harder jerk...

I think the cap flew about 3 feet above the lathe. With the lathe being 3 feet of the ground, thats a 6 foot fall to the concrete floor. I quickly grabbed the cap off the floor and gave it a good once over, fortunately it landed on the none machined surfaces and did not crack. But then, I notice a little bronze piece on the ground. It was the bearing expander.

The bearing expander fits in a recess in the bearing cap, if the cap is twisted off just right, it will grab the bearing expander, even with no screws attached, and rip it out of the bearing. Amazingly the rear bearing was fine, even though I could not put it back in again without sliding off the bearing. I drained and flushed the headstock, cleaned all oil passages, put the spindle assembly back together, checked spindle play by pushing and pulling with bar stock, got back to .001". Runs nice and smooth.

Lesson learned: leave one bolt in with a couple of threads engaged to keep the cap from flying off.

Aloha, Russell

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russell shigeoka
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