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Snag[_3_]

Lloyd E. Sponenburgh wrote:
Andrew VK3BFA fired this volley in news:db3ca6b6-
:

No machinists level, so will take it as a given the
bed is flat and true.

Is it between centres each end. (my first choice.)

If you did it using the 3-jaw chuck and the dead centre at the
tailstock method, as I have seen in places, would this not just
introduce more error into the process as the 3-jaw certainly aint
true ...and it would give a different offset every time you chucked
something up anyway.

You cannot assume the bed is level and true. That would be a
fundamental and fatal mistake. Beg, borrow, or steal one, or buy an
inexpensive Chinese version and true it up yourself before you use
it. Truing a level is quite easy; just make sure it can indicate
0.001" per foot.

CLEAN the level's base and the surface upon which you place it.

On small lathes that tend to flex a bit under cutting pressure, it's
common to have the tailstock center riding a couple of thousanths
higher than the spindle center. It should be dead-on fore and aft.

Note, I said, "center"(s). Clean the spindle bore and the tailstock
socket. Clean the centers. Gently "thump" them into place, but don't
drive them in. Make sure they have sharp, well-centered points.
Don't file them to a point, either have them re-turned on a precision
lathe, or buy some brand new ones.

After truing everything as well as you can, turn a "truing bar"
between centers, and as long as you can conveniently hold between the
centers, then check the diameters at both ends. If they're off, move
the tailstock fore or aft by half the error, and turn the bar's ends
again to check.

A truing bar is a length of stock that's thinner in the middle (by
only, say, 0.1") and with "hubs" on both ends upon which you do the
actual cuts for measuring. Take only very light cuts, and check
frequently.

LLoyd

Damn , Lloyd , I just told him almost exactly the same thing !

Great minds and all that ...

--
Snag
Learning keeps
you young !