Subject: Re-gringding lathe bed

From: "William J. Graf Sr." <[email-masked]>
Date: 19 Sep 1996 16:08:59 GMT

I have a South Bend 9" lathe and am thinking of getting the ways
reground and a new or better tailstock as the one on it is worn
and I have to use shims to get it parallel with the head.  I
used two centers, one in the head stock and one in the tail
stock to line them up, is that the correct way?  I live in the
Cleve. Ohio area and would like to know if anyone knows of a
company that can re-grind the ways and approximate cost.  The
bed is approx. 3 ft. in length.  Thanks in advance.
Bill

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From: [email-masked]
Date: 20 Sep 1996 13:30:01 GMT

>bed is approx. 3 ft. in length.  Thanks in advance.

I investigated this subject a while ago, and the conclusions I came to
were:  It is hard to find anyone with a surface grinder this large to
do the job for an amount of money that a home hobby machinst
would pay.  Plus when you are done, the underside of the saddle 
and the tailstock and the headstock would all have to be either 
re-ground or hand scraped. 

The saddle needs to be re-worked because it has worn to the shape
of the (worn) bed, and the tailstock has to be done because you 
*do* want to throw away those shims, right?  And when you are
done with that, the hole in the spindle is about 1/8 inch higher than
the hole in the tailstock - so it needs to be done, too.

As was pointed out to me by several people I had contacted, this
is a lot of work, and a lot of money if you pay to have it done.  
When you are all finished, you have learned a lot (don't get me
wrong, this a great way to learn, if that's your objective) but you 
still have a lathe which is a bit lacking.  

All of the older SB lathes I've seen have that shim under the tailstock - 
It does the job, and the worn bed is not a problem if you aren't trying
to turn within a thousanth over 3 or 4 inches of length.  If you are,
then you really need to get a better machine - re-working your 
existing one probably will be unsatisfactory in the end.  

These older machines are great to learn on - and I think they are passed
down from one machine student to the next.  Some folks improve them
and pass them on, others beat the poor lathe up before getting rid of 
it.  They are a kind of legacy from the industrial age between the 30's
and 40s in the US.  My 9" had the War Production Board sticker on 
it still, and had clearly been used in a production environment.   After
working for the war effort, it has gone on to train at least 3 individuals
that I know of.

I wonder what will happen when the last molecule of steel on these
lathes is worn away - will the interest in hobby metalworking 
evaporate as well?

Bottom line:  Consider trading up.  Sell the 9" to somebody starting 
out, and shop for a bigger, more rigid, more accurate machine. 

===========================================================

 1959 BMW R50                                           Jim Rozen              
 1969 BMW R60US                                (JRR0 @ watson.ibm.com)                 
 1975 BMW R75/6    (The "new" one)        

===========================================================

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From: [email-masked] (Russ Kepler)
Date: Tue, 24 Sep 1996 00:26:38 GMT

In article <[email-masked]>,
James Wilkins <[email-masked]> wrote:
>I've used a big horizontal milling machine to recut a well-worn lathe. It
>didn't do a perfect job but it took out the sag in the ways and there
>wasn't much left to remove by hand. The biggest problem is that the half
>nuts are no longer aligned with the leadscrew. 

I think that the current trick is to recut/grind the ways (or cut and
scrape as you did), then recut the V ways in the saddle, headstock
and tailstock and use Turcite (the Teflon bearing stuff mentioned
here) to rebuild the saddle and tailstock to proper height, gluing
and scraping shims into the headstock to reset its original height.
The Turcite will give a nice smooth action to the saddle and
tailstock, and shimming (with glue) and scraping the head restores
it's alignment with the lathe bed (if that's critical - it might be
easier to lower the hardware on the tail the amount removed from the
bed at the headstock).  

>Lindsay's book Machine Tool Reconditioning tells how to test and rescrape
>the lathe parts by hand.

Absolutely.  Some articles have been printed in _Home Shop Machinist_
and collected in "Projects Two" from them that gives a good view of the
rebuilding process, including the use of Turcite.

-- 
Russ Kepler							[email-masked]

                    Please Don't Feed the Engineers

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From: [email-masked] (James Wilkins)
Date: 23 Sep 1996 20:22:11 GMT

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From: [email-masked] (Chris Kantarjiev)
Date: 24 Sep 1996 16:52:57 GMT

My 9" had the War Production Board sticker on 
	it still, and had clearly been used in a production environment.   After
	working for the war effort, it has gone on to train at least 3 individuals
	that I know of.

As I think you'll recall, mine does, too. It's good to hear that there's
life after a War Production 9" ... I sometimes am dismayed of ever
getting this machine back together to make chips! (We prime the parts
tomorrow - it's getting close.)

Mostly what I worry about is that I'll have a beautiful looking machine
that won't cut true.

(Jim Rozen, I always have trouble replying to you - whatever machine
gets mail destined for "@watson.ibm.com" doesn't know the user jrro.
Your signature looks more like jrr0; maybe you need to fix your headers?)

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From: Charlie Greenman <[email-masked]>
Date: 27 Sep 1996 12:02:41 GMT

There should be no problem with the headstock/tailstock (or
bed turret) with a reground (or planed) bed. You're going
to be taking the same amount from both ends :-)

You will have to do two things (I've done this and it's
not hard):

You'll have to reposition the quickchange (assuming you
have one) so the leadscrew is correctly aligned for the
half-nuts and any other feed. The Logan has a spindle in
which the leadscrew rides and there's a key in the spindle
that engages with the slot in the leadscrew. This isn't
hard to do...  Measure the thickness of the bed ways before
grinding and after grinding and that's about how much you'll
have to change. Use shimstock to fit. Again on the Logan,
there's a machined surface on the top and back of the
quickchange and you shim it there. Move the tail end 
leadscrew support until the leadscrew is parallel to the
bed. Then disengage the leadscrew (withdraw both quickchange
handles) and be SURE you can easily rotate the leadscrew
when the self-act is engaged with the apron at all points
on the lathe bed. That's the first thing.

The other thing is you'll have to shim the rack under the
bed so it engages the pinion on the apron correctly. That
should be the same size shim as the quickchange. When it
is correct, you can put a piece of cigarette paper on the
rack, run the pinion over it and it will fold the paper to
the outline of the rack but not tear it.

None of this is rocket science. The hard thing about doing
lathes is getting the bed right (No idea how you do that
yourself) and then scraping the saddle to it. And while 
you're at it, you can scrape everything else! But the
headstock should be fine (and left untouched) and the
tailstock, once it's base is scraped, is aligned with
a shim between the base and top.

/Charlie