how far down can I bend the top of a South Bend 9 headstock bearing?

[Dick McBirney]

I am a mentor for a local high school robotics team. They have a South Bend 9 lathe with 0.006" of headstock bearing play. Although I know there is a peelable shim that can be reduced in thickness to tighten the bearing, removing enough shim to decrease the clearance about 0.004" makes me worry about cracking the headstock casting. What is the maximum shim thickness reduction allowed?

 

[chipss]

Nothing to it. .006 is nothing for the casting to flex. Peel away and get the bearing clearance to a half thou on both ends.

 

[Mechanixman]

I just brought mine back within, or close to tolerance from abkhr double your bearing play.
Part of my process was removing the next shim in the lack, which was a .004 shim on each side.
I wouldn't worry about doing it.

 

[4GSR]

His bearing caps are not split into separate pieces. Yes, it is possible to clamp them down enough to break off part of the bearing cap. Since the bore is badly worn, accuracy is not a real issue, I would apply heat to the cap as it is torquing down to close up the gap. Don't heat it up to cherry red, but somewhere in the 800-900 degree range. Do this without the spindle in place. Let cool, then install the spindle and tighten the cap down to the clearance needed. Just my opinion on what to do. Ken

 

[jmm03]

with the appropriate size shims properly located under the cap wouldn't the cap pull straight down on the spindle and there would not be any bending involved?

 

[Conrad Hoffman]

AFAIK, the bearing cap is not a separate piece and the casting has to bend to take up the clearance. I didn't know they made 'em that way.

 

[jmm03]

ah, I am used to the 10L style, I did not realise the 9 was so different, thanks. Jim

 

[chipss]

Older 9's had removable bearing caps. His is this style with one bolt doing the tightening.