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

You could alter the lead screw where in enters the gear box. The way to do
this is to cut in in two and rejoin the pieces with a coupling and a "shear"
pin. That's the way the feed screw on my lathe is set up. I'd think the
lead screw would work that way two. Of course I'd use a solid steel pin
here instead of the aluminum pin on my feed shaft.

Smoke

-----Original Message-----
From: Chris Hellyar <chris@...>
To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
Date: Sunday, November 12, 2000 10:23 PM
Subject: 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
>
>
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