In article ,
artfulbodger wrote:
wrote:

A lathe with two headstock
feet and a single tailstock foot would be ideal. It seems you could
plunk such on a level floot and go right to work because three point
contact defines the position.

I don't know why all lathes, or at least all benchtop lathes, aren't
made with three feet. There's no such thing as a wobbly three-legged
stool.

Consider the possibility of the bed having machined without
sufficient time for it to stress relieve. (They used to allow them to
season for some time after roughing before final machining.)

Now, the bed will warp *after* final machining. With a
three-point suspension, you have no way to apply stress to cancel that
warp. With four-point, you are fine.

Of course, jeweler's lathes are single-point support -- a column
under the headstock end. But the overall design suggest to me that
there is very little need to make provisions for corrective stress on
those -- there is a *lot* of meat in the beds for their size.

Now -- also think of a long bed lathe, with a fairly heavy cut.
This could introduce twist to the bed under load -- either a cut from
the carriage, or twist applied by driving a big drill bit into the
workpiece. For something like this, the four-foot design gives it extra
anti-twist support.

But -- FWIW -- the Atlas/Clausing 6x18 lathe has a three-point
mounting -- at least my old one with sleeve bearings and a blue paintjob
does. I believe that the later ones with the ball or tapered roler
bearings in the headstock have the four-point mounting.

I've thought of putting an iron block under the tail-end feet of my
lathe: both feet would bolt to it, and its bottom would be a shallow
vee. There would be a narrow land in the center, with a single bolt
hole for mounting to the bench. Of course I'd put the head end on a
similar, but flat bottomed, block.

The only problem I can think of is that everything could end up too
flexible. I don't know. Would my nice, fairly stiff lathe get all
vibratey if I did this? Anyone got any thoughts about it?

Try it and find out. Try heavy drilling with a Morse taper
twist drill in the tailstock taper. Try heavy cuts near the end of the
bed. See what happens.

Be prepared to make a second tailstock end block with all four
feet if it introduces problems.

And report back on your results.

Right now, I like the four-foot mount for my Clausing, with
factory supplied hollow bolts threaded through the feet, and smaller
bolts through it all to clamp it down to the factory pedestal. I did
have to do a bit of tuning to get everything level. And that was not
that long a bed (24" between centers) for the size of the swing (12")
and the bed width.

Enjoy,
DoN.

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