I came upon a steady rest designed for ways that consist of one
80-degree V and one flat. Does anybody know what make and model of
lathe this could be for? (It isn't Clausing 5900 - that's a 70 degree
V-flat.)

Joe Gwinn

On Fri, 14 Jun 2013 11:29:16 -0400, Joe Gwinn
wrote:

I came upon a steady rest designed for ways that consist of one
80-degree V and one flat. Does anybody know what make and model of
lathe this could be for? (It isn't Clausing 5900 - that's a 70 degree
V-flat.)

Joe Gwinn

It's not a SB 10L. All three Vs appear to be around 92 degrees, just
checking it quickly.

--
Ed Huntress

In article , Ed Huntress
wrote:

On Fri, 14 Jun 2013 11:29:16 -0400, Joe Gwinn
wrote:

I came upon a steady rest designed for ways that consist of one
80-degree V and one flat. Does anybody know what make and model of
lathe this could be for? (It isn't Clausing 5900 - that's a 70 degree
V-flat.)

Joe Gwinn

It's not a SB 10L. All three Vs appear to be around 92 degrees, just
checking it quickly.

Yes, my recollection is that all SB lathes use 90-degree Vees.

Joe Gwinn

On Fri, 14 Jun 2013 12:22:03 -0400, Joe Gwinn
wrote:

In article , Ed Huntress
wrote:

On Fri, 14 Jun 2013 11:29:16 -0400, Joe Gwinn
wrote:

I came upon a steady rest designed for ways that consist of one
80-degree V and one flat. Does anybody know what make and model of
lathe this could be for? (It isn't Clausing 5900 - that's a 70 degree
V-flat.)

Joe Gwinn

It's not a SB 10L. All three Vs appear to be around 92 degrees, just
checking it quickly.

Yes, my recollection is that all SB lathes use 90-degree Vees.

Joe Gwinn

I thought so too until I put one of my steel protractors on them a
little while ago. I couldn't fit my vernier protractor in there, so I
had to use a sliding-leg protractor with no degree marks. It
definitely looked sharper than 90 degrees.

But I was working half in the dark -- my light fixture just went out.
g

I'll take a closer look this weekend.

--
Ed Huntress

"Ed Huntress" wrote in message
...

It's not a SB 10L. All three Vs appear to be around 92 degrees,
just
checking it quickly.

I thought so too until I put one of my steel protractors on them a
little while ago. I couldn't fit my vernier protractor in there, so
I
had to use a sliding-leg protractor with no degree marks. It
definitely looked sharper than 90 degrees.

Ed Huntress

The square end of a steel rule is a nearly light-tight fit in the
internal vee of my SB 10L micrometer stop.
jsw

On Fri, 14 Jun 2013 16:18:34 -0400, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .

It's not a SB 10L. All three Vs appear to be around 92 degrees,
just
checking it quickly.

I thought so too until I put one of my steel protractors on them a
little while ago. I couldn't fit my vernier protractor in there, so
I
had to use a sliding-leg protractor with no degree marks. It
definitely looked sharper than 90 degrees.

Ed Huntress

The square end of a steel rule is a nearly light-tight fit in the
internal vee of my SB 10L micrometer stop.
jsw

I'll transfer the angle to a vernier protractor and see. If I hadn't
gotten the same result on all three, I'd chalk it up to making a bad
fit.

--
Ed Huntress

On 14/06/13 16:29, Joe Gwinn wrote:
I came upon a steady rest designed for ways that consist of one
80-degree V and one flat. Does anybody know what make and model of
lathe this could be for? (It isn't Clausing 5900 - that's a 70 degree
V-flat.)

Joe Gwinn
Not a Harrison M300 as that has 75 degree V ways from my quick check.
Posting a picture would help as the style would help determine if it old
or new.

In article , David Billington
wrote:

On 14/06/13 16:29, Joe Gwinn wrote:
I came upon a steady rest designed for ways that consist of one
80-degree V and one flat. Does anybody know what make and model of
lathe this could be for? (It isn't Clausing 5900 - that's a 70 degree
V-flat.)

Joe Gwinn

Not a Harrison M300 as that has 75 degree V ways from my quick check.
Posting a picture would help as the style would help determine if it old
or new.

Hmm. I will remeasure the Vee angle. These measurements are a bit
clumsy to make, and errors are a danger. I think I'll try some
variation of the two rods (different diameter penetrates to different
depth in the V) approach.

I will also take some pictures and measure some dimensions.

I found no casting numbers anywhere. The only numbers found are the
numbers 68 and a star, both hand-stamped into the machined flat
adjacent to the Vee groove. I interpret the 68 as meaning that the
rest was made in 1968, and the star as indicating who made it, or
perhaps what part of the manufacturer's line it went with.

Joe Gwinn

"Joe Gwinn" wrote in message
...

Hmm. I will remeasure the Vee angle. These measurements are a bit
clumsy to make, and errors are a danger. I think I'll try some
variation of the two rods (different diameter penetrates to
different
depth in the V) approach.

Joe Gwinn

You could trim a small piece of sheet metal to nearly the correct
angle, press the straighter edge against one side of the internal vee
and scribe a line parallel to the other side.

Measure it, construct a more precise sheet metal template at the
suspected angle with a vernier protractor, and see if it fits
light-tight.

Can you tell that I have many years of experience making precise
measurements with office supplies and rinsed-out soda cans?
jsw

On Sat, 15 Jun 2013 12:53:04 -0400, "Jim Wilkins"
wrote:

I checked my SB again, with some light this time. g It is 90
degrees, not 92. Apparently the protractor was slipping as I tightened
the nut.

--
Ed Huntress

"Ed Huntress" wrote in message
...
On Sat, 15 Jun 2013 12:53:04 -0400, "Jim Wilkins"
wrote:

I checked my SB again, with some light this time. g It is 90
degrees, not 92. Apparently the protractor was slipping as I
tightened
the nut.

--
Ed Huntress

It's not an easy measurement.

If you built small things for a living these could be justified:
http://www.starrett.com/metrology/me...ortBy=none/asc

I bought a new 14D from a local supplier for $10, long ago, and a
pristine used 453C set for $7.99. The second knob on the 453C tilts
the blade up to 7 degrees to measure the draft angle in a punch press
die.
jsw

In article , Jim Wilkins
wrote:

"Joe Gwinn" wrote in message
...

Hmm. I will remeasure the Vee angle. These measurements are a bit
clumsy to make, and errors are a danger. I think I'll try some
variation of the two rods (different diameter penetrates to
different
depth in the V) approach.

Joe Gwinn

You could trim a small piece of sheet metal to nearly the correct
angle, press the straighter edge against one side of the internal vee
and scribe a line parallel to the other side.

Measure it, construct a more precise sheet metal template at the
suspected angle with a vernier protractor, and see if it fits
light-tight.

I did think of that, and I do have a vernier protractor, but the
two-rods method seems simpler and more accurate. Certainly less
fiddly.

But I do have the precisely-made rods (drill blanks) and a indicator.
That plus some math should yield a precise answer.

The two rods approach is a standard way to measure inside Vee angles,
according to some old toolmakers books I've read. (Don't recall which
one.)


Can you tell that I have many years of experience making precise
measurements with office supplies and rinsed-out soda cans?

Yes. It's certainly a good make-to-fit approach. Is rinsing necessary?

Joe Gwinn

In article , Joe Gwinn
wrote:

In article , Jim Wilkins
wrote:

"Joe Gwinn" wrote in message
...

Hmm. I will remeasure the Vee angle. These measurements are a bit
clumsy to make, and errors are a danger. I think I'll try some
variation of the two rods (different diameter penetrates to
different
depth in the V) approach.

Joe Gwinn

You could trim a small piece of sheet metal to nearly the correct
angle, press the straighter edge against one side of the internal vee
and scribe a line parallel to the other side.

Measure it, construct a more precise sheet metal template at the
suspected angle with a vernier protractor, and see if it fits
light-tight.

I did think of that, and I do have a vernier protractor, but the
two-rods method seems simpler and more accurate. Certainly less
fiddly.

But I do have the precisely-made rods (drill blanks) and a indicator.
That plus some math should yield a precise answer.

The two rods approach is a standard way to measure inside Vee angles,
according to some old toolmakers books I've read. (Don't recall which
one.)

Following up to my own post, I performed the rods measurement using
five different test rods.

Details: Clamped the rest upside down in a vice, so the base is on
top. Cleaned machined surfaces with acetone and a razor blade.
Clamped a magnetic base to the flat, with arm and digital indicator
over the Vee groove, with indicator probe moving vertically and more or
less perpendicular to the plane of the flat. Installed the 0.500" rod
and zeroed the indicator. Took indicator measurements on five rods,
being 5/8, 1/2, 13/32/ 23/64, and 5/16 inch diameter. Fitted a line to
the data, and also used a formula on measuring tapers using discs of
various diameters from Machinery's Handbook (27th edition, page 715, in
Angles and Tapers).

The consensus answer is 79.7 degrees included angle; one assumes that
the target was 80 degrees. One would assume that people don't sweat
getting Vee-groove angles exact on steady rests.

This measurement is likely accurate enough to exclude the 75 degrees of
Harrison lathes.

By the way, after I cleaned and inspected everything, I think I misread
the hand-stamped number. I had read it as 68, but I now think it's
actually 89, as in 1989.