On May 16, 6:12*am, Bruce in Bangkok wrote:
On 16 May 2009 04:18:47 GMT, "DoN. Nichols"
wrote:





On 2009-05-15, RogerN wrote:

"Ignoramus2991" wrote in message
...
Would anyone know if a 7.5 HP 16x40 lathe would be able to run from a
10 HP idler. I am sure that power reversing would not be possible, but
would it be able to start it at higher RPM?

i

I have a 10HP idler in my shop and have started my 7.5HP mill motor and a
7.5HP(or 10HP, don't remember) 18" X ~72" lathe. *The lathe started very
slow but it did start. *I never tried power reversing.

* *The *real* test is to put a heavy chuck (e.g. the typically
larger 4-jaw) on the spindle, close the jaws on something so they don't
spin loose, set for the highest spindle speed (within the safety range
of that chuck, of course), start it at that setting, and once it is up
to speed, reverse it and see what happens. *The only more sever test
would be to have a maximum diameter workpiece (which will clear the
cross-slide) the length of the lathe between centers -- or perhaps
reversed jaws and the largest diameter workpiece which is short enough
to not walk out of the jaws without tailstock support. :-)

* *If you have variable speed pulleys, you may have to start it
first to be able to run the speed up, then stop it and re-start. *With a
gearhead lathe or pure step pulleys, you should be able to set it up for
maximum speed without jumping through those hoops.

* *But be sure that you aren't in the path of chuck jaws or
workpieces coming loose at high speeds. *They can be quite dangerous.

* *Good Luck,
* * * * * *DoN.

I once worked in a shop that had a couple of lathes with screw on
chucks - the mount by screwing them onto the headstock spindle. One of
the blokes used to use reverse to brake the lathe and tried it while
he was polishing something, in high gear. The chuck came off and made
about two laps around the shop bouncing off machines and walls.
Luckily, no one was hurt.

But it is kind of exciting to see a 16 inch three jaw chuck do a burn
out and launch on a concrete floor :-)

Cheers,

Bruce in Bangkok

That sounds like a good argument for a single phase motor on a belt-
driven lathe. My belt drive, threaded spindle lathe came with a 3
phase motor which I swapped for a 1 phase TEFC. If I accidentally push
the drum switch to Reverse instead of Stop the lathe just keeps
running forward. It won't reverse until it has slowed down enough to
close the start switch.

What is the lathe operation that is said to require instant reverse?

jsw