In article ,
"DoN. Nichols" wrote:

On 2008-03-09, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-03-08, Joseph Gwinn wrote:
In article ,
"DoN. Nichols" wrote:

On 2008-03-07, Joseph Gwinn wrote:

[ ... ]

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. :-)

But the carbide tool has more uses.

Not if if is ground to cut Acme thread profiles at the 10 TPI
size. There is not much else that it can do.

Right.

And solid carbide tools are *expensive*. I've got a 1/2" solid
carbide boring bar with a silver-soldered end which forms the pocket for
an insert (with flats on top and bottom to assure the proper rotational
angle and keep it from squitting out from under the clamp screws), and it
was something like $135.00 on an eBay auction -- and in catalogs it is
well over $200.00, so I figure that I got a deal at that price. And at
least that has replaceable inserts, so I can use it for boring for quite
a while. It is amazing how little chatter you see with as much as 6"
extension of that 1/2" diameter rod. So -- if you could find an Acme
insert, this would be the tool of choice for making internal threads,
except that it is too large to produce a 1/2" Acme -- and based on other
information later on, I think that the leadscrew in question is smaller
than 1/2". Hmm ... let me go down and check on that before it gets too
late.

Solid Criterion or Criterion-like bars turn up used around here for a
few dollars, but usually need some cleanup with a grinder.

And the Chinese are learning how to make these as well.


O.K. The spare compound has a 3/8-10 Acme leadscrew. Now how
much can you do with that and a between centers bar? A 1/8" tool bit
would not have *any* meat around it after leaving clearance for the
threads. Let's see -- total height of thread is 0.060" for 10 TPI,
times 2 = 0.120" subtracted from major diameter of 0.375 gives us
0.255". For a rod to fit into that, with a transverse square broached
1/8" hole leaves us 0.065" total wall thickness -- not much for a
setscrew to hold the bit -- and that leaves no clearance for the chips or
for withdrawing from the thread between passes.

There are smaller bits than 0.125", which is far larger than needed to
cut a 10 tpi acme thread. In round numbers, if the pitch is 0.100",
then the tool width is something like 0.060", which can be made from a
piece of 0.1" drill rod, leaving ample space for a small setscrew.


And 3/8-10 Acme is *not* a standard thread -- even right-hand,
and at least the compound leadscrew (unlike the cross-slide) is a
right-hand thread.

No -- I think that I would turn the needed thread in drill rod,
cut flutes, harden and draw it, and grind the flutes to sharpen it.

This is indeed the traditional approach.


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.

The center of the rod could be turned down for chip clearance without
badly reducing the stiffness.


It would be slow for sure, but the point of holding both ends with
cutter in the center is a substantial increase in rigidity compared to a
bar held from one end only.

And I left out of the calculations the fact that it would have
to be small enough to allow both the bar *and* the projection of the
tool to cut the full thread to slide into the bore before cutting
threads. And if it is *just* right in size, it makes how far you back
out of the thread prior to cranking back for the next pass more
sensitive.

I visualize it as having a small bit held in a cross hole, held by a
perpendicular setscrew. One may need to use a 1/8" bit, such as used
for jewelry lathes.

Covered above -- now that we are down to a 3/8" thread, there is
not even enough meat for this -- complete with about 1/16th inch of
sidewall for the threads for the setscrew. And the setscrew could not
be allowed to stick up above the bar, either.

Also covered above. Jewelers and clockmakers do this kind of stuff all
the time - same idea, but in miniature.


Yes -- but how do you adjust the tool protrusion for the
subsequent passes? That is the tricky part, especially with a bar small
enough to clear both the cutting tool and the bar diameter through the
bore. You *do* have to advance the tool out of the bar, you can't do it
with the cross-slide leadscrew.

Correct. The cross-slide does not move during this operation.

By loosening the setscrew and moving the bit, using a depth mike to set
the protrusion as one creeps up on the correct cut depth.

A tricky bit of work -- especially with such a tiny setscrew. I
would rather try making a tap to serve the function.

Not that tricky. But I'm coming around to the make-a-tap school as
well. One can also order taps made. I don't recall the price, but it
wasn't astronomical. This was discussed on RCM a while ago.


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

I missed that you said "Compound Slide" at first -- which
changes everything. The "Tee" shaped nut is for the main cross-slide,
not the compound. (Just to be sure -- which *is* it which is so loose?
My backlash was in the cross-slide -- the one which always moves at
right angles to the lathe bed, instead of the one which can be set to
different angles depending on need.

The looser axis is the one closest to the T-Slot, and which can be set
at various angles to the lathe bed ways.

The axis perpendicular to the bed ways is also loose, but far less so.


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.

So it appears - this axis is by far the loosest.

I should measure wear on the screw - perhaps all I need is to replace
the nut.


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.

Try page 19 in the 5418 manual. Both nuts are shown. The cylinder nut
is DL-471 and the T-shaped bronze nut is 990-069. The nuts on the 5914
look exactly the same.

Oh -- you are talking about the nut for the *compound*, not the
cross-slide. That looks even smaller in the drawings -- perhaps 3/8"
instead of 1/2". I thought that we were talking about the cross-slide
on the carriage, not the compound top slide.

How did we get that far apart?

I've been trying to follow the nomenclature in the Clausing manual, for
better or for worse, even when it seems counter-intuitive. But I
suspect that nomenclature isn't uniform between manufacturers, which is
why I started to give the actual part number as well.

O.K. Let me define *my* terms so we can be talking about the
same thing:

1) The "Longitudinal leadscrew" -- leadscrew under the front lip
of the lathe bed running behind and partially through the apron.

2) The "Saddle" or "Carriage" -- that which moves along the lathe
bed either under control of the leadscrew (when threading) or a
rack under the lip of the bed and a pinion in the apron (the
front of the carriage). The pinion can be turned either by the
handwheel, or by gearing driven by a keyway in the longitudinal
leadscrew.

3) The "cross slide" -- the part which moves at right angles
to the bed via a crank on the top area of the apron, driven
either by hand on the crank, or by gearing inside the apron
driven by the keyway in the longitudinal leadscrew.

4) The "Cross Slide Leadscrew" -- the leadscrew which moves the
cross slide above the carriage. Note that the dial on the cross
slide *may* be calibrated to read twice the actual motion, so it
represents diameter removed instead of radius. This makes sense
since it only moves at right angles to the lathe bed, so it will
always remove twice its motion in diameter from the workpiece.
Whether it reads diameter or radius is at the whim of the
manufacturer -- and you need to check when moving from one lathe
to another to avoid nasty surprises. :-)

5) The "Compound assembly" or just "Compound" -- bolts to the top
of the cross slide with provisions to adjust its angle relative
to the bed. It can move at any one angle depending on setting.

6) The "Compound Assembly Leadscrew" -- Here, the dial is usually
(but not always) set up to read the actual motion, since it can
be operated at any angle -- so it may represent diameter
removed, or length of stock removed, or some combination of the
two.

It's a logical system for sure. But honored in the breech, as discussed
below. This is why I try to say how far from the T-slot or bed way an
item is.


On the 5914, the slide is flat-topped, not humped.

You mean the compound, not the cross-slide? I wonder why?

In the 5914 manual (page 30), that T-slotted part is flat-topped and is
called the "Tool Post Slide" (704-033), and is dovetailed to the
"Compound Slide" (704-034), which in turn rotates upon the "Cross Slide"
(704-032).

In the 5418 manual (page 19), that same part is humpbacked and is called
simply the "Slide" (C-330), and is dovetailed to the "Lower Compound"
(DL-460), which rotates upon the "Cross Slide" (DL-458).

So, even within Clausing, the nomenclature varies. Thus the confusion.

Thus my listing of my own usage of the terms above -- so we can
talk about the same thing.

And the taper attachment only works with the cross-slide
leadscrew, not the compound leadscrew.

Yes. Makes sense, and the drawings support this. Any you have one and
can look at it.


OK. Comparative benefits?

[ ... ]

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.

Sounds like non-telescoping would be best for me as well.

And -- it should cost less, too. :-)

Yep. And now to find one.

It took me two or three years, of following eBay auctions to
find one which I *thought* would work -- and then some time to figure
out how it was supposed to work (and what parts I needed to make to
complete it) once I got it. Later, I got a manual for both it and the
telescoping one and discovered that I was right -- and only slightly off
in one thing -- a washer under the clamp for the "traveling nut" which I
made on the surface grinder to be the right thickness should really have
been bent from the proper sheet steel to this shape (be sure to view
with a fixed pitch font like Courier to avoid distortion of the image):

/|_______/|
// O //
|/ |/
+--------+

Note that the hole designated by the 'O' should be centered in the
bottom plate -- but I would have to make the ASCII drawing much larger
to allow that -- and I still could not keep the scale right, so I'll
leave it as it is.

I assume that anti-rotation is the intent, and that one could make this
washer with a vertical mill as well.


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.

Will do, although it will be hard to see that the bottom of the slot is
spherical versus cylindrical.

That was not what I was trying to determine. I just wanted to
see what it looked like so I could tell whether it felt Clausing-made to
me.

OK.

We may no longer need this, if we both agree that it is possible
that it was not a Clausing original.

OK. Yes - no proof either way.

It would make sense for Clausing to buy the toolpost assembly, versus
making it themselves.


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.

One assumes that the name somehow involved or implied the word
"diamond".

I don't find anything useful with a Google search using the
words Diamond and toolpost. Actually, I find mostly woodworking tools
in the first hits. :-)

That was my experience too. But I've seen that trademark before on
tools.

O.K. My original thought when "diamond" was mentioned was about
the non-slip texturing of the surface on which the tool holder rests.

It has those to, but this is clearly a trademark symbol, not a
functional feature.

I'm going to Aloris as well.


Or even from some other brand of lathe entirely. All I really know is
that the post itself looks like what's in the Clausing manual, and that
the washer was not made by Armstrong.

O.K. But the post is a very common design -- or at least was
back then.

Maybe the cheap fix is to buy an Armstrong washer and rocker to fit the
existing lantern post. J&L carries Armstrong toolposts et al.

Or -- to turn a ring to match the rocker which you have?

That would work too.

But the toolpost ring (J&L ART-89423L) is $18 and the rocker
(ART-89443D) is $11, so maybe I'll just buy them.

By the way, their seat radius is 2-7/8 inch, which may well work with
the slotted ring I hav.

So -- turn a disc of that radius and see how it fits. Perhaps
start oversized so you can creep up on the proper dimension.

Yep.


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

I wouldn't make it _too_ strong, as subsequent parts are ever larger and
more expensive to replace.

Well ... it is stronger mostly thanks to the materials which I
was able to find -- a good tough tool steel instead of cheap cast iron.
I wasn't setting out to make it stronger -- that is just what happened.
:-)

I think I would have made the replacement out of good quality cast iron,
not steel, so if something is to break in the future, it will be the
T-slot, not the saddle or whatever. Think of the T-Slot as a mechanical
fuse.

At the time -- cast iron was not available to me. I was working
with scrap available at the local shop at work (along with the tools to
shape it) and had no idea where to order such things.

Now -- it looks so much nicer than the original (thanks to the
surface grinder final finish) that I am reluctant to change it -- and I
don't use that lathe any more, anyway. (There are enough other problems
so it is not worth the effort, and it is in the cellar, not the garage
which became the shop. For things that small, I have the 5" CNC lathe
by Emco-Maier which is a much better machine than the old
Atlas/Craftsman with the bronze spindle bearings and the worn
flat top ways.

OK. That makes sense.

I suppose I will outgrow the Clausing someday, but it won't be that soon.

Joe Gwinn