Re: [CAD_CAM_EDM_DRO] Re: re:Lathe Rack & pinion.(cnc lathe)

Hurro...

> manual lathe! Does your "customer" require you to keep all
> the "manual" stuff? Or does he/she want a CNC lathe?(with manual

? Customer..

Now that's an idea, charge him for "consultancy" and then use the money to
buy myself a real CNC lathe... :-). at $50 and hour that'll take, um, ages.
This is a friend from my old work, he's just brought the lathe from a
machine shop that replaced it's heavy iron with CNC gear. He saw my baby
lathe cutting some prop adaptors a month or two ago, and has decided he'd
like to try the same thing on a larger scale.

> IMO, You will spend much more in time to "keep everything as it is,
> Just add a little CNC please" than to just CNC the lathe!

I'd agree, but I think he wants to keep the fully manual option available.
There is already a decent sized CNC machine in the shop so I suspect this is
more of an experiment than anything else. Although he's just got a quote
for the 3phase AC servos, $13,000 with amps... I suspect he has much deeper
pockets than me, and I think that's just about what he paid for the whole
lathe as well.

> P.S. I have a love for old tools, so if its a "nice one", I'd re-
> think the whole thing! And just leave it manual :-)

It's big, ugly and chinese. And we're not talking nice chinese either, it's
from the early 80's before the cheap import lathes got their quality
problems sorted out. It looks like a scaled up version of the old boxfords
they used to use in schools here in NZ. Even though it was made in 1981
(according to the serial # plate) it looks like it leapt right out of a WWII
manufacturing plant.

> P.S.S. If you have room you "could" clamp or thread a timing belt
> pulley on the far end of the existing L/S. You said the L/S appeared
> cast-in-place? Not likely, IMO, but if so you could make/use

Not really cast in place..

The right end (free end) sits in a bush in the casting with an Oil bell.
The driven end is captive in the gear housing. To remove it you'd have to
remove the gear housing, as the right end mount is part of the main bed
casting, which is a right pain. taking the gearbox off looks like a major,
and unless there is a hidden join somewhere it is a huge bit of metal,
probably the thick side of 300-400kg of cast iron. Did I mention that this
lathe is not small? It would probably swing 800mm over the bed, and about
3m between centres. Mike makes big pumps, of the sewerage variety. Major
heavy metal work.

> a "split" timing belt pulley, and just drive the existing L/S. You
> said it was a tight fit with the half-nuts :-) Disengage the pinion

I think most of the friction in the lead is due to the the interrupted
thread and a massively worn nut.. I'd not trust it past threading type revs
anyway, it's long, and doesn't look that rigid, I'd think it'd whip quite
badly if a rapid traverse was asked of it.

Anyway, I'm going over there after tea to see if the rear side ball screw is
an option, then I'll also see about my consultancy fees :-).

Cheers, Chris.

* Design engineer, Assembly worker, Cleaner.
* Ohmark Electronics. PO Box 5302, Christchurch, New Zealand.
* http://www.ohmark.co.nz