leveling lathe

I'm trying to get my lathe level and the instructions call for "along the length of the tracks, error

Reply to
stu
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"stu" wrote: (clip) Thats 2/100000ths isn't that just a little insane? ^^^^^^^^^^^^^^^^^^ It would be, if that is what it meant. I think it means you are allowed .002" per meter. ^^^^^^^^^^^^^^^^^^ My lathe is like this but about 1080 between centres ^^^^^^^^^^^^^^^^^ Your lathe is 1.08 meters, so give yourself a couple tenths over .002.

Reply to
Leo Lichtman

Reply to
Bruce In Bangkok

Stu, No, it isn't insane. It is necessary for accuracy and easy to do if you have the appropriate level. Lathe beds look very stiff, but they do twist. Please remember that it is not "level" per say. A lathe will function quite well out of level, as in ship installations. It is all about the parallelism of the spindle and bed. Level is the common reference for that alignment. To do this correctly, you need two tools, a machine level and a precision test bar for the spindle. Steve

Reply to
Steve Lusardi

If you don't have the precision level, there's always " Rollie's Dad's Method"

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Karl

Reply to
Karl Townsend

Karl, This method will verify the spindle to a straight bed. It will not allow you to attain a straight bed, because you are only testing with carraige in a single location. There is no substitute for a machine level......if you don't have one, get one. Steve

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Steve Lusardi

Reply to
alan200

Doesn't that method move the carriage from one end to the other, allowing you to look for differences in the distance from the carriage (toolbit) to the workpiece, and when adjusted properly, you will no longer turn tapers? Isn't that the goal of the level? Why spend a hundred bucks or more on a level when a dial indicator will do the job? /mark

Reply to
Mark F

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Steve Lusardi

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stu

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pentagrid

Reply to
Bruce In Bangkok

news.optusnet.com.au...> I'm trying to get my lathe level and the instructi= ons call for "along the

Reply to
Jim Wilkins

Stu, That is exactly how you do it. Here is a tip for those lathes that sit on a stand or cabinet, jack the back of the lathe casting off the bed, drill and tap the rear legs, insert jacking screws, with level in place, adjust the jacking scews and tighten the mounting bolts as required to regain bed straitness. Then measure any gap with feeler gauges. Make a shim to that dimension and insert for the permanent fix. Steve

Reply to
Steve Lusardi

Jim, Consider yourself lucky your bed casting is straight. They are often not. If you read the South Bend book on installing and setting up your lathe, they tell you to jack the bed straight with the mounting bolts. Steve

Reply to
Steve Lusardi

I kept the posting simple. This 1965 South Bend Heavy 10 mounts on a relatively light sheet-metal cabinet. It can be shimmed level but the tailstock end of the bed also has a pivot in its support with two opposed adjusting screws to correct twist, independently from the cabinet. In this case the bed straightened itself and I only had to snug up the screws carefully, they can move it out as easily as into alignment.

I just rechecked it with a VIS level, 0.0005" / 10". The bubble is equal within one mark at both ends with a 0.010 shim on the front way, and it turns straight to ~0.001" with all the errors of bed wear, Enco collets, replacement tailstock parts and general age and decrepitude.

Rather than changing the bed I readjust the top of the tailstock whenever I move it and need to turn accurately between centers, which isn't that often. Then I center the dead center with an indicator in the chuck. It has other problems beside bed twist; the lathe came from a trade school where the kids used the tailstock spindle for an anvil. The top of the tailstock was a VERY tight press fit on the base and the clamping block underneath obviously a student project.

Jim Wilkins

Reply to
Jim Wilkins

Agreed, but for most hobbyist lathes, gravity won't be the killer. And what about shipboard machines, rockin' and rollin'...? /mark

Reply to
Mark F

I gave up trying to shim as I don't have the equipment to make my own and the feet on my lathe are only 200mm(8 inches) apart. Even the thinnest thing I could find alum foil at 0.01mm (0.0004) twists the lathe

0.05mm/1000mm(0.006/foot, I think) and is a pita to fit. I "reinvented" a mounting system similar to this one.
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haven't been game yet to "pull" the casting straight. I've also read about lathes "unwinding" over a few days, so I might just leave it for a few days and see what happens.

Thanks Stuart

Reply to
stu

As yet I don't have a straight edge. But the way I see it the sag would be less than half 0.0039. If the bed was "bent" in the middle with flat bed either side of the bend, the sag would be 0.0039/2 so 0.00195. but the sag would me more like part of a circle or parabola. I'm starting to think I'm worrying about nothing.

Any lathe is a big step up for me, I just want to be sure i'm not going to damage it. Thanks Stuart

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stu

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