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wear in cross-slide nut contribute to lathe chatter?

I have a venerable 1949 South Bend 9" lathe. Sadly, its cross-slide nut (or screw, or both) have a fair amount of wear, as I can grab the cross-slide table and move it nearly 1/16" with my hands. I'm whittling down a block of 303 stainless and it seems like it's taking forever. The machine is cutting the 303, but I can only advance the cutter about .010" between passes, and reducing the diameter .020" at a time is going to mean a lot of lathe work. I don't really have to do it, of course, but it has led me to wonder if the slop in my cross-slide screw actually contributes to lack of rigidity while turning. I have always figured as long as the slack in the screw was taken up, it wouldn't make any difference whether there were .004" of backlash or .040". Yet I don't have a complete understanding so I thought I'd post this to the group. There is an advertiser in HSM that offers new cross-slide nuts and screws for my lathe at what seems like a reasonable price.

GWE

Reply to
Grant Erwin
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I recently replaced that nut on my Atlas 10" lathe. I had about the same amount of slop. Glad I did it. My big problem was that with all that slop, the tool could dig in at the drop of a hat, making for inaccurate work. I guess that could easily look like a rigidity problem.

Pete Stanaitis

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Grant Erw> I have a venerable 1949 South Bend 9" lathe. Sadly, its cross-slide nut

Reply to
spaco

All lathes unless equipped with ball screws have backlash in the crossslide & compound screws. While turning there is continous pressure against the tool so backlash really doesn't matter, assuming your tool is above or at center. If you let your tool below center it can get dragged into the work, for instance when parting off.

I wouldn't worry about it unless the backlash is more than 3/4 of a turn, & then only because it becomes difficult to remember where the correct reading is when approaching the surface of the work.

Rigidity comes more from the snuggness of your gibs.

Tony

Reply to
Tony

Use a tool that pushes toward the chuck without exerting any forward pressure. It will work much more effectively and you will get a strighter cut since you have a mimimum of pressure to deflect the piece.

Any loseness in the compound and cross slide will be a lot less of a problem.

John

Reply to
John

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