Subject: Hydraulic tracer lathe

From: Jerrold Beall <[email-masked]>
Date: Wed, 26 Jan 94 20:07:58 -0500

I am looking for a used tracer lathe....Particularly Myford Mini-Kop
or Harrison.
 
J.R.Beall.....pls respond by E Mail if you have info....Thanks

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From: [email-masked] (John Kopf, X6305)
Date: 28 Jan 94 20:21:59 GMT

> J.R.Beall.....pls respond by E Mail if you have info....Thanks

I'd be more interested if anyone have ever BUILT a tracer attachment?  From
scrap?

JK

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From: [email-masked] (Ron Ginger)
Date: 31 JAN 94 20:30:08

In article <[email-masked]>, [email-masked] (John Kopf, X6305) writes...
>I'd be more interested if anyone have ever BUILT a tracer attachment?  From
I built one for a Unimat. A rather simple device. I arranged a bar parrallel to
the ways and fixed about 2" back of the ways. It has a rabet along the edge and
several tapped holes. A pattern is filed or whatever, from thin stock,
30-50thou thick. Brass or even plastic works.

The cross feed screw is removed so the slide is free to slide back and forth. A
pointer is attached to the slide to ride against the profile of the template.
The compound is used to apply the cut depth, and simple hand pressure against
the slide forces it against the template. Apply power feed and let it go.

It would be a nice refinement to add a spring to hold the slide in contact
with the template.

I have considered offering it as a product from my Model boat business, but
havent quite decided how much market there would be for such a gadget. Im
waiting for a Sherline lathe on which I also expect to make one.

Ron ginger
Pleasant Cove Models
17-N Potter Rd
Framingham MA 01701

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From: [email-masked] (John Morton)
Date: 1 Feb 1994 02:17:27 GMT

In article <[email-masked]>,
>the slide forces it against the template. Apply power feed and let it go.

I have seen a tracing arrangement which is used on a Mycroft lathe for 
very exact profiles.  There is a laser mounted on the carriage, pointing 
vertically upwards (it is about 6" long and cost $100).  The frame which
supports the laser also carries a little pin, which is an inch or two
from the laser's lens.  The pin is the swivel axle for a 1/2" square
mirror, which in it's normal position is at ~45 deg. to the horizontal.

The mirror is stuck to a bit of sheet metal which is bent at an angle,
so that while the mirror itself is at 45 deg., the other half of the
sheet metal bit is vertical, and is held at about that orientation by
a horizontal pointer which is attached to the compound (which is in the
90 deg. position).

Do you get the picture now?  Small movements of the compound screw (and 
hence the toolbit) produce slight changes in the angle of the mirror,
which in turn produces large changes in the position of the little red 
spot on the wall behind the lathe.  A cut of .001" is clearly distinguish-
able!

The man who uses this arrangement has an indicator on the compound, which
he uses to set each desired compound and carriage position, according
to data obtained from the object he is duplicating (in his case it is
the bore of an old flute, from which he has taken measurements in a
museum).  Each position is then charted by marking the position of the
red dot on a sheet of paper behind the lathe.  The marks are blended
with a pencil.  Then he just puts a disc the size of a steering wheel
on the compound screw and steers the red dot as the feed carries it
along :-).

If you think about it, this method is perfectly suited to the purpose,
even though the graph of the dot's movement is not in direct correspondence
to the shape produced.  

John Morton					University of California
[email-masked]			Mechanical Engineering
{decvax,cbosgd}!ucbvax!euler!jmorton		Machine Shop

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From: [email-masked] (John Kopf, X6305)
Date: 3 Feb 94 20:24:20 GMT

In article [email-masked], [email-masked] (Ron Ginger) writes:
> <stuff deleted>
						  ^^^^^^^^^^

A lot depends on what you're trying to do.

In my current case, I need ~24 BRASS cannon for a ship model -- 2"long x 1/4
dia.  My FINEST feed is 100 tpi...200 turns will go from one end to the other.
Being SMALL-diameter brass, I need a high speed (say 3000 rpm).  If I use the
power feed, the entire cut is done in 1/15th second!  If I let the stock hang
WAY out to give me more time, it whips.

I end up avoiding power feed, and do it by hand.

JK

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From: [email-masked] (f.w.kerfoot..iii)
Date: Sat, 5 Feb 1994 14:44:33 GMT

>From article <[email-masked]>, by [email-masked] (John Kopf, X6305):

I assume you mean 1/15 of a minute (200 revolutions / 3000 R/Minute), but
that is still very fast. 100 TPI is .010"/rev, which is a fairly high
feed as the smallest value. I think my South Bend has feeds less than
.001"/rev. Are you sure there isn't a way to set up slower feeds? Is it
a QC or a manual change? As an alternative, you can of course cut brass
at slower speeds. It will just take more time. You may not get the
surface finish you want at .010"/rev, however.

Frank Kerfoot
[email-masked]