Hi,

I've noticed that I haven't been getting much
support from my tailstock when turning longer items,
so I set up an indicator to measure just how much
support I wasn't getting, and found that at 4"
extension, the end of the ram could move .012 with
hand pressure, unclamped, .010 clamped. Retracting
to 0" extension, I could move it about .004",
clamped. In both cases, I was measuring front-to-
back, but imagine the vertical number would be
similar. Adding washers under the clamp handle had
no effect.

Now the remedy: If this were something common like a
Southbend, Logan, or Monarch, I'd just try to track
down another tailstock. It's a 14" Hendey, 1890's
vintage. Probably not going to happen, so probably
best to try to repair what I've got.

Removing the ram and playing with a mic, I get 1.622
diameter everywhere I measured it. I haven't measured
the bore yet. I just got some telescoping gages, so
will have actual numbers on that later.

My options as I see it a
1. Bore out the tailstock and make a new ram.
Probably the simplest option, as the ram itself is
fairly simple, 9-1/8" long, 1-5/8" diameter, MT3
socket, LH acme thread on the back for about an inch
or two, one 1/8" keyway on the bottom, one oil groove
on the top. Possible fly in the ointment: making the
new ram without a good tailstock. I do have a steady,
but I haven't used it yet.

2. Rebore and have the ram plated and reground. Sounds
like this could get expensive in a hurry since I would
have to have someone else do this.

3. Rebore and sleeve to fit existing ram. If I do
this right, I may be able to bore out to fit standard
tubing, pressfit or locktite in place (as I'm not
experienced enough to trust my ability to get a good
press fit on this), then rebore this insert in place
to fit the ram?

4. Shim the clamp end of the tailstock bore with
something like sheet brass or aluminum, locktited in
place. A hack, if it would work at all.

Which would you choose, and why? Are there others
that I haven't thought of? (I can hear the rumble
of "yeah, get a newer lathe" from the back, and
while this may yet happen, it won't be soon).

In most these cases, I am looking at reboring the
tailstock. Would you expect being able to get
anything approaching reasonable results with a boring
bar held in a chuck and running in a steadyrest on
the far side of the tailstock? The handwheel end
of the tailstock casting looks like it doesn't come
off, so that end of the bar would have to fit through
the root diameter of the leadscrew, maybe 1/2", if
that. I'd expect that rigidity could be a problem
(understatement). At least the diameter from the
chuck up to the cutter could be larger, possibly up
to 1-1/2". Any other not-to-obvious gotchas?

Thanks,
--Glenn Lyford

Glenn Lyford writes:

3. Rebore and sleeve to fit existing ram.

I'm wondering if you couldn't turn the ram smaller, epoxy on Teflon or
Turcite sheet, and turn that to the original bore size. That's how flat
ways are rebuilt to original sizes, and the techniques aren't difficult.
Might even improve on the original rigidity.

In article ,
Richard J Kinch wrote:

Glenn Lyford writes:

3. Rebore and sleeve to fit existing ram.

I'm wondering if you couldn't turn the ram smaller, epoxy on Teflon or
Turcite sheet, and turn that to the original bore size. That's how flat
ways are rebuilt to original sizes, and the techniques aren't difficult.
Might even improve on the original rigidity.

You might be able to use Moglite?

--
Free men own guns, slaves don't
www.geocities.com/CapitolHill/5357/

Just wondering if you've considered or if anyone else has an experience with
something like Brownell's Electroless Nickel plating. Plate it until the
fit is tight again. Would seem like this would be a good application.

Steve.


"Glenn Lyford" wrote in message
. ..
Hi,

I've noticed that I haven't been getting much
support from my tailstock when turning longer items,
so I set up an indicator to measure just how much
support I wasn't getting, and found that at 4"
extension, the end of the ram could move .012 with
hand pressure, unclamped, .010 clamped. Retracting
to 0" extension, I could move it about .004",
clamped. In both cases, I was measuring front-to-
back, but imagine the vertical number would be
similar. Adding washers under the clamp handle had
no effect.

Now the remedy: If this were something common like a
Southbend, Logan, or Monarch, I'd just try to track
down another tailstock. It's a 14" Hendey, 1890's
vintage. Probably not going to happen, so probably
best to try to repair what I've got.

Removing the ram and playing with a mic, I get 1.622
diameter everywhere I measured it. I haven't measured
the bore yet. I just got some telescoping gages, so
will have actual numbers on that later.

My options as I see it a
1. Bore out the tailstock and make a new ram.
Probably the simplest option, as the ram itself is
fairly simple, 9-1/8" long, 1-5/8" diameter, MT3
socket, LH acme thread on the back for about an inch
or two, one 1/8" keyway on the bottom, one oil groove
on the top. Possible fly in the ointment: making the
new ram without a good tailstock. I do have a steady,
but I haven't used it yet.

2. Rebore and have the ram plated and reground. Sounds
like this could get expensive in a hurry since I would
have to have someone else do this.

3. Rebore and sleeve to fit existing ram. If I do
this right, I may be able to bore out to fit standard
tubing, pressfit or locktite in place (as I'm not
experienced enough to trust my ability to get a good
press fit on this), then rebore this insert in place
to fit the ram?

4. Shim the clamp end of the tailstock bore with
something like sheet brass or aluminum, locktited in
place. A hack, if it would work at all.

Which would you choose, and why? Are there others
that I haven't thought of? (I can hear the rumble
of "yeah, get a newer lathe" from the back, and
while this may yet happen, it won't be soon).

In most these cases, I am looking at reboring the
tailstock. Would you expect being able to get
anything approaching reasonable results with a boring
bar held in a chuck and running in a steadyrest on
the far side of the tailstock? The handwheel end
of the tailstock casting looks like it doesn't come
off, so that end of the bar would have to fit through
the root diameter of the leadscrew, maybe 1/2", if
that. I'd expect that rigidity could be a problem
(understatement). At least the diameter from the
chuck up to the cutter could be larger, possibly up
to 1-1/2". Any other not-to-obvious gotchas?

Thanks,
--Glenn Lyford

Glenn Lyford wrote in
:

Glenn,

The way our production machines are repaired, is to grind enough stock off
of the quill to clean up any wear, then bore, sleeve and rebore the
tailstock housing.





--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

In article , Glenn Lyford says...

Removing the ram and playing with a mic, I get 1.622
diameter everywhere I measured it. I haven't measured
the bore yet.

First off you should be *absolutely sure that the clamp
mechanism is functioning the way it should.

Some of them clamp via a slit alonside the casting, so that
the clamp bolt actually tightens up the bore. There are
others that have a two-piece clamp that self-centers in a
vertical hole, and pinches the ram. What kind of setup
does this Hendy have?

My experience is that the bores and the rams wear at about
equal rate. So finding the ram dimension constant along
its length implies to me that the bore might be OK. The
amount of slop that you see when the clamp is snugged down
is pretty large - large enough to imply to me that something
is wrong with the clamp setup.

If the bore really *is* bell-mouthed then you probably need to
worry about opening it up and fabricating a new steel ram.
This is not trivial to do, as you need to get the MT socket
in the center of the ram to be right on axis, on both planes.

Boring the tailstock casting is tough because of the rigidity
issues you mention. Plus you want to take as small a cut
as possible of course, so the bar is subject to chatter. I think
it would be informative to figure out how those bores are formed
in the first place.

I wonder if a reamer would provide an accurate enough hole - would
it follow the existing hole axis close enough, and cut to size
even though the existing hole is bell-mouthed?

Jim


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Nick Hull writes:

You might be able to use Moglite?

Casting Moglice doesn't seem appropriate for this closed geometry.
Applying and machining Teflon or Turcite is relatively simple by
comparison.

On 11 Dec 2004 10:14:13 -0800, jim rozen
wrote:

In article , Glenn Lyford says...

Removing the ram and playing with a mic, I get 1.622
diameter everywhere I measured it. I haven't measured
the bore yet.

First off you should be *absolutely sure that the clamp
mechanism is functioning the way it should.

Some of them clamp via a slit alonside the casting, so that
the clamp bolt actually tightens up the bore. There are
others that have a two-piece clamp that self-centers in a
vertical hole, and pinches the ram. What kind of setup
does this Hendy have?

My experience is that the bores and the rams wear at about
equal rate. So finding the ram dimension constant along
its length implies to me that the bore might be OK. The
amount of slop that you see when the clamp is snugged down
is pretty large - large enough to imply to me that something
is wrong with the clamp setup.

If the bore really *is* bell-mouthed then you probably need to
worry about opening it up and fabricating a new steel ram.
This is not trivial to do, as you need to get the MT socket
in the center of the ram to be right on axis, on both planes.

Boring the tailstock casting is tough because of the rigidity
issues you mention. Plus you want to take as small a cut
as possible of course, so the bar is subject to chatter. I think
it would be informative to figure out how those bores are formed
in the first place.

Now that's a good question !

I had mine nickel plated twice and ready to lightly polish in the
other lathe , haven't got around to that part yet , but it holds tight
now backwards. It has a slit on the back side like Jim said above and
from the same era as yours.

If you bore it out I'd like to see pictures of the set up and how the
TS is driven. I've thought about doing it that way , but I don't think
my lathe is really worth the trouble. Hmmm , bolt the carriage and TS
together and a SR. Still , the ram would be hard to remake.


I wonder if a reamer would provide an accurate enough hole - would
it follow the existing hole axis close enough, and cut to size
even though the existing hole is bell-mouthed?

Jim

I vote for building up the worn part with hard chrome and having it
cylindrically ground to size. - GWE

In article , Grant Erwin says...

I vote for building up the worn part with hard chrome and having it
cylindrically ground to size. - GWE

But the ram is not worn. It has constant diameter over its
whole length.

Jim


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Glenn Lyford wrote:
....
Now the remedy: If this were something common like a
Southbend, Logan, or Monarch, I'd just try to track
down another tailstock. It's a 14" Hendey, 1890's
vintage. Probably not going to happen, so probably
best to try to repair what I've got.
....

From the other replies it seems as though your repairing this one might
be kinda tricky. Maybe you should reconsider a replacement, but with a
twist: how about adapting a SB, Logan, whatever to your lathe. Get a
slightly smaller one and machine a plate adapter. It seems to me that
the machining would be less demanding. Not that I've ever done this, so
maybe somebody else can comment.

Bob

jim rozen wrote:

In article , Grant Erwin says...

I vote for building up the worn part with hard chrome and having it
cylindrically ground to size. - GWE

But the ram is not worn. It has constant diameter over its
whole length.

Jim

Perhaps the implications of increasing the tailstock ram diameter
by plating slipped by? Common practice would be to rectify the
tailstock housing and plate & grind the ram to suit.

Tom

jim rozen wrote:

In article , Grant Erwin says...

I vote for building up the worn part with hard chrome and having it
cylindrically ground to size. - GWE


But the ram is not worn. It has constant diameter over its
whole length.

OK, Jim, I know you are no dummy. What *is* worn? If you have a funky
worn bore in your tailstock body then I vote for boring and resleeving.

If the bore's OK but the ram is worn then I vote for plating and then
regrinding. Tricky, that, because you don't want to plate the ID taper ..

Grant

In article , Tom says...

But the ram is not worn. It has constant diameter over its
whole length.

Perhaps the implications of increasing the tailstock ram diameter
by plating slipped by? Common practice would be to rectify the
tailstock housing and plate & grind the ram to suit.

The hard part is repairing any out-of-round condtion in the
bore of the casting, IF there is any.

Because this has yet to be measured, I have to withhold any
other suggestions.

But to reply to your point, I guess I would fabricate an new
ram from scratch, rather than chrome the old one.

Jim


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From the other replies it seems as though your
repairing this one might be kinda tricky. Maybe
you should reconsider a replacement, but with a
twist: how about adapting a SB, Logan, whatever
to your lathe. Get a slightly smaller one and
machine a plate adapter. It seems to me that
the machining would be less demanding. Not that
I've ever done this, so maybe somebody else can
comment.

OK, I've heard of others doing this too. And I'd
still have the original tailstock to play with, too...
--Glenn Lyford

Removing the ram and playing with a mic, I get 1.622
diameter everywhere I measured it. I haven't measured
the bore yet.

OK, playing with my new telescoping HF bore gages
I get the following:

Inches ===== Measurement plane =====
in from Horiz. Vert., Vert.,
end unclamped clamped
------ ------ ------ ------
0 1.626 1.628 1.625
1 1.626 1.625 1.624
2 1.625 1.625 1.623
3* 1.623 1.623 1.622
4 1.623 1.622 1.622
*- End of the clamp slit.

Some of them clamp via a slit alonside the
casting, [...] What kind of setup does this
Hendy have?
The slit type, not the two-piece type.

If the bore really *is* bell-mouthed

Numbers pretty much say it is.

I think it would be informative to figure out
how those bores are formed in the first place.

Took another look at the assembly, and there is a
hole on the bottom side of the bell end where the
handle attaches. A blind hole. A spanner hole.
Ten seconds later, the entire handwheel and end
bell assemble is loose in my hands, and I'm looking
through a large bore, straight through the
tailstock. _Much_ better! Now I can go way up with
my boring bar ability. The only possible concern
here is the threads for the end bell are directly
in the tailstock bore, so I'd have to stop whatever
process I use short of mangling those threads.

I wonder if a reamer would provide an accurate
enough hole - would it follow the existing hole
axis close enough, and cut to size even though
the existing hole is bell-mouthed?

Enco has an adjustable reamer that goes up to
1-13/16ths for $35. Since I don't have to worry
about end-bell clearance, an adjustable would work,
and it looks like the majority of hand and chucking
reamers stop at 1-1/2. But I would expect boring
would give me a more accurate hole should the wear
not be even front-to-back or top-to-bottom, whereas
the reamer would follow the hole as worn, yes?
--Glenn Lyford

Richard J Kinch wrote:

I'm wondering if you couldn't turn the ram smaller, epoxy on Teflon or
Turcite sheet, and turn that to the original bore size. That's how flat

I've never used Turcite so can't comment on that but I've done lots with
Teflon. Teflon will cold flow so doesn't work well anywhere significant
pressure is involved. UHMW polyethylene would be much better in this
application.

Ted

Ted Edwards writes:

Teflon will cold flow so doesn't work well anywhere significant
pressure is involved.

Despite this oft-heard glib dismissal, plain Teflon (PTFE) works well for
reconstructing machine tool ways.

"Cold flow" is a misnomer. The phenomenon is properly called creep, an odd
mechanical property where the yield strength for plastic deformation is a
function ot time. But for PTFE, this is still only significant only at
1000s of psi, which is not present in ways.

Machine tool bearing surfaces do not typically exceed more than a few 100s
of psi transiently, and much less statically. This is by design to ensure
rigidity and lubrication. This makes them good candidates for PTFE
rebuilding. Indeed, machine ways are carefully designed to ensure that
forces are never concentrated anywhere on the bearing surfaces. The same
principle fits PTFE properties quite well.

In article , Richard J Kinch
says...

Machine tool bearing surfaces do not typically exceed more than a few 100s
of psi transiently, and much less statically.

Except for the clamping action of a the tailstock casting
on the ram. I would say that pure ptfe is a poor choice
for that application.

Jim


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jim rozen writes:

Machine tool bearing surfaces do not typically exceed more than a few
100s of psi transiently, and much less statically.

Except for the clamping action of a the tailstock casting
on the ram. I would say that pure ptfe is a poor choice
for that application.

If you mean the narrow longitudinal strip of the ram which is engaged by
the clamp, yes, you would leave that as bare metal. It's not a bearing
surface anyway.

Note that with a polymer bearing surface, you could create a negative
clearance on the ram vs bore. This would eliminate both play and stiction,
which are typically why you need a clamp at all.

If you have a saw slit with a clamp screw which clamps the quill, you
should measure the width of the slit at a point away from the clamp
screw, towards the back of the tailstock. Whatever this dimension is,
put a shim in the slot near the mouth of the quill with that dimension,
and clamp on the shim. The hole will then be near the original size.
Now the "T" gauges will measure the hole diameter correctly. If it is
off, then bore the hole out to get parallelism and ensure EXACT center
height for the hole.

Using the new bore dimensions, make a new quill. Make the quill with
steps in this order. First bore a through hole in a piece of steel
which is the root diameter of the thread at the back of the quill.
Thread the hole to match the screw. Put an accurate, 60 degree chamfer
to match a dead center around the perimeter of the threaded hole. Turn
the quill blank around and bore the hole to the small diameter of a
dead center (2 morse taper, or three morse taper or whatever). Using
the center rest, bore the morse taper to match a test taper. If you
can get a finish reamer, use it to get the final taper perfect. Insert
a dead center in the taper, and mount the quill between this dead
center and another in the taper at the threaded end. Turn the OD to
match the hole in hole in the tailstock casting. The weapon of choice
here is a post grinder if you have one.

If you have done everything correctly,. the hole in the taper will be
concentric with the outside of the quill, and the hole in the tailstock
casting will be at center height.

brownnsharp

In article .com, brownnsharp
says...

Using the new bore dimensions, make a new quill. Make the quill with
steps in this order. First bore a through hole in a piece of steel
which is the root diameter of the thread at the back of the quill.
Thread the hole to match the screw.

Another approach is to leave the threading to the last, and then
bore the backside to accept a cylindrical bronze nut that is
pinnned in place. This makes the ram threads easily replacable,
and it separates the fabrication job into smaller bites.

Jim


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In article , Glenn Lyford says...

Inches ===== Measurement plane =====
in from Horiz. Vert., Vert.,
end unclamped clamped
------ ------ ------ ------
0 1.626 1.628 1.625
1 1.626 1.625 1.624
2 1.625 1.625 1.623
3* 1.623 1.623 1.622
4 1.623 1.622 1.622
*- End of the clamp slit.

...I would expect boring
would give me a more accurate hole should the wear
not be even front-to-back or top-to-bottom, whereas
the reamer would follow the hole as worn, yes?

Yes it would I think. If you just stuffed a reamer in there,
the tailstock would probably droop by quite a lot afterwards.
So boring it is a good way to go.

Do you know anyone with a milling machine with a long enough
travel, to simply set it up and do it in one shot? In this
case of course you would want to indicate to the ways on the
underside of the tailstock, or to the bottom part of the
upper casting, if it's a split casting. The latter would
be a bit better if the tailstock way surface were worn.

Jim


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jim rozen wrote:

Another approach is to leave the threading to the last, and then
bore the backside to accept a cylindrical bronze nut that is
pinnned in place. This makes the ram threads easily replacable,
and it separates the fabrication job into smaller bites.

That is a very good suggestion. My Smithy tailstock was made that way
with a threaded cast iron bushing locked into the end of the ram. When
the threaded bushing wore out I made a new one from bronze. Details may
be seen at
http://www.metalworking.com/dropbox/_2001_retired_files/TAILSTOK.TXT
and associate drawing and photo.

Although my problem was different than the OP's, the conversion would
make the job easier.

Also, if the OP has a boring head, it could be mounted in the lathe
chuck. The tailstock could be positioned such that it could be moved
with the longitudinal feed and the tailstock could be bored on the
lathe. This should make for excellent alignment.

Ted