Subject: WANTED: Watchmaker's Lathe

From: [email-masked] (J Kuhlman)
Date: 29 Dec 1994 12:13:54 -0500

My father is interested in purchasing a watchmaker's (or jeweler's) lathe.
 E-mail any specs and prices.

Thanks in advance.

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From: [email-masked] (J. Kimberlin)
Date: 12 Jan 1995 09:03:07 -0800

In article <[email-masked]> [email-masked] (Barry Workman) writes:
>[email-masked] (BILLG63475) writes:
>
>>Check out a company named Sherline! Their phone # is 800-541-0735. They
>>have a complete line of miniature machine tools and accessories! They may
>>look like toys in the catalog, but they are really fine pieces of
>>equipment and are very reasonably priced! I have been using them in my
>>work for 5 years now and also have a mill and a lathe at home. I am
>>currently converting both to computer control CNC. I have a commercial CNC
>>conversion on my deluxe Sherline mill at work and have been very happy
>>with it! If you are at all interested in CNC feel free to EMAIL me!
>
>Wait, wait, wait.  Sherline makes small GP lathes and mills.  They don't
>make a Watchmaker's Lathe.  I've seen one available in the US "off the
>floor" and that was a Prazi available from either IPS or Rutland.  The
>cost on the little thing was over $1500 as I recall but guaranteed
>+/- .0003!

I think you guys are talking about little lathes but not instrument or 
watchmakers lathes.  Sherline, Prazi, etc, are not very accurate in the 
same sense as a watchmakers lathe is, nor nearly small enough to be 
classified as a watchmakers lathe.  Brands such as Boley, Bergeon, or 
Levin lathes with all their attachments cost around $5000 or more.  There 
are many brands now out of business - Lorch, Favorite, Gamma, Lanco, 
Leinen, Wolf-Jahn, etc.

A book on the subject is:  The Watchmaker's and Model Engineer's Lathe (A 
User's Manual) by Donald de Carle, published by Rovert Hale Ltd. 
Clerkenwell House, Clerkenwell Green, London EC1R 0HT.

Incidently, Clerkenwell Road in London has many many shops catering to 
the watchmaker's trade.  It was once the London center of watchmaking and 
still has a few shops carrying old parts for lathes, etc.  The book can 
be found at H. Walsh & Sons, Ltd. advertising occasionally in Model 
Engineer, phone 01-253-1174.

JerryK

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From: [email-masked] (Ron Ginger)
Date: Thu, 12 Jan 1995 19:29:53

......

>cost on the little thing was over $1500 as I recall but guaranteed

what does 'guaranteed +/- .0003' mean?

if it means the run out of the spindle bearings, then almost any normal ball 
bearing is that good. I just looked at a Fafnir bearing catalog, the specified 
runout for bearings of about this size in class 1, the lowest quality made, is 
.0003. The highest class list only drops it to .00005 ( 1/2 a tenth).

It cant mean the handheels are clibrated to be that accurate,  Ive never 
seen a handwheel with .0001 calibration- most have .001, some are calibrated 
to radius.

It obviously cant mean the quality of work produced, because in the hands of a 
sloppy worker it will only do what the worker directs.

Most watchmakers lathes dont even have calibrated collars, since most 
watch and clock work is done with hand tools.

If you look at how accurately the carriage runs to the lathe axis, the 
Sherline has an adjustable headstock for taper turning, so it turns just as 
true as the indicator youuse to alignit and your accuracyof work.

 so, just how do you rate the 'accuracy' or 'precision' of a lathe?

Ron Ginger
my signature is http://www.ultranet.com/~ginger

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From: [email-masked] (Barry Workman)
Date: Thu, 12 Jan 1995 04:14:27 GMT

-- 
    - Barry Workman

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From: [email-masked] (James Kirkpatrick)
Date: 13 Jan 95 12:34:17 MST

Ron Ginger asks:

That's a good question.  Many years ago there may have been a
common understanding of what this meant, but these days nobody
seems to guarantee anything to do anything.

One measure I've read is that if you turn a bar between centers,
over the max length the lathe will accomodate, and take a turning
cut, that the diameter will not vary by more than this amount.
This tells you that the carriage ways are straight and that the
centers line up well. (I *think* I read this definition in the
Taig literature but it's not handy right now).

There's still the question of the compound feed.  If I face a plate,
the same sort of question might apply:  how flat is the resulting
surface?

I have some literature on Vectrax vertical mills (an MSC in-house
name brand, but basically the common Taiwan/Chinese mills), and they
do state several very specific measurements and even have photos of
the setups they use to make the measurements.  A nice touch but you
do pay for these babies!

There are *many* ways to state accuracy of such machines, as
Ron points out.

Jim

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From: [email-masked] (Robert Mitchell)
Date: Mon, 16 Jan 1995 16:37:31 GMT

>the same sort of question might apply:  how flat is the resulting

This discussion started out about watchmaker's lathes.  My Boley, like	
most of the old lathes, has a hardened shaft riding in steel bushings.
No ball bearings.  Also no carriage and no compound feed, so no measuring
turning cuts.
In this environment, all work is done with collets, and the only figure
of merit of interest is runout at the headstock.
In that regard, most are excellent.	

 - Robert Mitchell

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From: [email-masked] (JJCrom)
Date: 22 Jan 1995 19:05:12 -0500

The Derbyshire company is still in business in Massachusetts.  They have
been making lathes for the watchmaking trade for the better part of the
century (mine was made in 1902 and is still in fine shape).  Check out the
classified ads in Home Shop Machinist magazine.   One HSM advertiser,
Sobel Machinery, has had several different types of Derbyshire lathes for
sale during the last couple of years.  Warning:  they ain't cheap!
    Justin