On 2008-03-07, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

[ ... ]

Actually, a taper attachment is higher on my list. I did see a
telescoping taper attachment for a Clausing lathe other than 5900 series
listed on eBay yesterday, but gone today. Taper attachments are
model-specific, so I didn't pay much attention.

O.K. Though the ones for the 5400 series and for the 5900
series may be interchangeable -- depending on how the nut is
implemented.

Details, details.

Well ... you are talking of your nut being a cylinder, while
mine is a "Tee" so there could be interchangablity problems. This might
require the telescoping taper attachment to fit.

[ ... ]

I bet that Aloris keeps them pretty accurate, so their industrial
customers don't yell at them.

But the distance from the dovetails to the center of the bore
on a boring bar holder is not a critical dimension for use as designed.

Nonetheless, I bet it doesn't vary much.

Probably not -- but is it accurate enough for substituting for a
turret? (And you would need an easy way to lock the cross-slide so it
did not vibrate off center.

[ ... ]

Too late to check those out tonight. I'm due in bed. Been
tearing apart a dead HP LaserJet 5 color so I can get it down the
stairs. That thing is *heavy* when fully assembled. I'll keep typing
until my watch completes its try to contact WWVB to verify its time
setting at 2:00 AM. :-)

Reading patents can substitute for counting sheep.

Not according to my wife. :-)

Most of the problem seems to be in the nut. Maybe I'll make a new nut.
It was pretty simply shaped, and an Acme tap set is probably cheaper
than a new nut from Clausing. It's $48.50.

First thing to be careful about. The thread is 1/2-10 Acme
*LH*, and all of the combination roughing/finishing Acme taps have been
right-hand only. I did get a left-hand Acme tap of the right thread,
but IIRC it cost nearly as much as the nut at that time.

Hmm. Cut on the lathe?

Cut the leadscrew on the lathe -- with a follower rest. I tried
one in aluminum as an experiment, but I made the mistake of cutting it
right-hand thread, so the test failed. But it looks as though I can do
a good job.

It ought to work, although I would have to fabricate a follower rest for
the job as well.

O.K.


However, I think that trying to do internal threading with a
single-point tool for a 1/2" diameter leadscrew in bronze (nasty stuff
to thread with a flexing tool) might be beyond me.

Use a solid carbide internal threading boring bar?

Compare the price of a solid carbide internal threading tool
ground for left-hand thread 10 TPI Acme to a left-hand Acme tap at 10
TPI. :-)

Or, mount the nut on the slide and a bar between centers with HSS
toolbit in the center of the bar, perpendicular to the bar, the bar
passing through the nut. I've seen this setup used for line boring of
bearings on electric motors.

Again -- the bar is likely to be pretty skinny. The minor
diameter for a 1/2" 10 TPI Acme (LH or RH won't make much difference)
for class 2G threads is:

Max: 0.3800"
Min: 0.3594"

so -- with a 3/8" rod, and max diameter you would have 0.0025" clearance
for the chips -- and all other options are less. Anything smaller than
3/8" diameter would be even worse in terms of rigidity (and even windup
of the rod). I don't think that I would want to single-point that
thread.

[ ... ]

What does your nut look like? Mine looks like a plumbing Tee,
with the Acme thread through the two straight sides, and the upright of

[ ... ]

The nut I'm talking about is a cylinder with the threaded hole
crosswise. It is part number DL-471 (Compound Slide Nut) on page 30 of
the Clausing manual.

Hmm ... how does it attach? IIRC, my Clausing manual does not
cover that style. And it is too late to dig it out to be sure.

The cylinder fits snugly into a hole in the Compound Slide (704-34), and
is held in place by a single setscrew.

O.K. So the hole is a lot shorter than it is in the "Tee"
design and the cylinder is mounted with its axis vertical? That would
interchange with the original Tee -- but would wear a lot faster with
fewer threads engaged.

The T-shaped nut is part number 5900-37 (Cross Slide Nut Assembly) also
on page 30.

No page 30 in my manual. Mine stops at page 20 -- exclusive of
the un-numbered lubrication chart.

[ ... ]

So that's the distinction between telescoping and non-telescoping taper
attachments. What are the advantages and disadvantages of the two
approaches?

The non-telescoping one uses the standard leadscrew and threads
it into a nut which can be clamped either to the back of the cross
slide, or to the follower on the taper attachment.

Ahh. And it's bad karma to engage both clamps at once.

Yes -- though not too bad as long as you don't have the slide
clamped to the bed -- or if the taper bar is set to zero taper.


The telescoping style has the crank connected to a spline which
fits into the leadscrew, and the far end of the leadscrew threads into
the the follower and is mounted in a bearing in the cross slide, IIRC.
(I should dig up the manuals on PDF to see which is which, but the watch
has completed its resetting. It and the computer now agree to the
second, instead of being off by a full second. :-)

OK. Comparative benefits?

Telescoping: Cost is much higher for the telescoping version.

Telescoping: The backlash in the spline adds to the total backlash in the
handwheel.

Telescoping: No juggling of two clamps to determine whether you are
in taper or non-taper mode.

Non-Tele: Cost is lower.

Non-Tele: less backlash.

Non-Tele: A bit more rigid in non-taper mode, because you don't
have the path going out to the follower and back as you
do in the Telescoping. And in the Tele, is *always* in
taper mode -- other than locking the slide to the bed.

I would probably prefer the telescoping if I were switching back
and forth a lot between taper and non, but for occasional use I prefer
the non-telescoping (which happens to be what I already have,
simplifying matters.

[ ... ]

I have no way to know if what I have is true Clausing. What I have was
machined, not forged, and lacks Armstrong markings. Although the rocker
could have been forged. Or forged then machined. Not having the
rocker, it's hard to say.

It may be a shop-made replacement.

I think I was unclear. The slotted washer appears to have been made by
Clausing,

Why does it appear to have been made by Clausing?

Style and finish, basically. I cannot see a shopmade item going to all
that trouble, versus buying something from Armstrong.

O.K. But the only drawing of the lantern style toolpost is the
page offering "Carriage Saddle and Compound Assembly" (Page 19) in my
manual. And the drawing of the ring looks like it is fully dished -- no
hint of a single groove like yours. The ring is C-375, and the whole
lantern style toolpost, less wrench, is C-377-S. The rocker, FWIW, is
C-378.

Could you do a good set of close-up photos of the ring and drop
them in the dropbox (http://www.metalworking.com). Direct e-mail to me
won't work -- there is a size limit on incoming e-mail which would
bounce it.

By the way, I looked at the Armstrong website, and the rocker I bought
was not made by Armstrong, although it looks to be interchangeable with
Armstrong. What I have is marked with a flattened diamond and the
number "10". Any idea who makes or made this?

No clue -- unless that is an older Armstrong. The number of
toolpost parts which they currently make is a lot fewer than they used
to make. Everybody is going Aloris style or equivalent.

[ ... ]

O.K. Perhaps. But the ring sounds more like shop-made unless
you see markings to indicate that it was made by Clausing. Just because
it came with the lathe does not mean that it has always been with the
lathe. :-)

Clausing does not seem to mark the pieces of their lathes, only the
lathe itself. As mentioned above, I doubt that the ring was shopmade.

O.K. But the slotted version is not shown in the manual
drawings for the 5418 at least. Can you find drawings showing the
slotted version in your manual?

[ ... ]

Ouch. That Atlas was just a bit too light duty. What was being parted
off that caught the parting tool?

It was a length of square stock -- 4?? stainless steel as it
turns out, about 1-1/4" square which was too long to support the far end
by a tailstock center, and I had no steady rest even if I had the
ability to make a square to cylinder adaptor -- which I did not at that
time. And, I did not have a horizontal bandsaw at the time, either.
Nor did I have the patience to use a hacksaw on it.

I was cutting off about 1" from the 4-jaw chuck jaws. Really
asking too much of such a light duty lathe. :-)

I'll say. Interrupted cut and all.

Actually, I was into the continuous cut point before it failed.

With the new compound top, some other part would fail first, I
think. :-)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---