Threading on a "slow to stop" lathe
 

"Ignoramus25487" wrote in message
...
I tried threading a 3/4" shaft with it recently.

My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

What is the standard approach to this problem.

First, turn a "land" at the point where you wish the threads to stop. Make
the diameter just at, or a couple-thou under the minor diameter of the
thread.

IF you have a threading dial, and don't have to reverse your lathe to get
back to the start of the threads --

When the tool enters the land, disengage the longitudinal feed (halfnuts),
then stop the lathe with the tool still in the land.

Watching carefully, you can stop in a land barely more than one thread pitch
wide.

If you don't have a threading dial, be right quick on the cross-feed, and
back the tool out rapidly when it hits the land. Then stop the lathe,
reverse, etc.,etc..

LLoyd

In article , Ignoramus25487 says...

What is the standard approach to this problem.

1) leave a runout zone for the threading tool to dwell in
when you unlatch the half nuts, or

2) use a dial indicator on the carriage that winds to zero
where you want the thread to stop. Unlatch the halfnuts
at that point and allow the tool to make a circular groove
there, after the thread is done go back and put a radius
at the bottom for strength - or,

3) use three phase power and plug reverse the lathe to
a stop at the desired location.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

Ignoramus25487 wrote:
On Mon, 23 May 2005 15:11:59 GMT, Lloyd E. Sponenburgh
wrote:

"Ignoramus25487" wrote in
message ...
I tried threading a 3/4" shaft with it recently.

My problem with it is that the lathe is very slow to stop. When I
turn
the lathe off, it takes a few revolutions for it to stop. There is
no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

What is the standard approach to this problem.

First, turn a "land" at the point where you wish the threads to
stop. Make
the diameter just at, or a couple-thou under the minor diameter of
the
thread.

IF you have a threading dial, and don't have to reverse your lathe
to get
back to the start of the threads --

When the tool enters the land, disengage the longitudinal feed
(halfnuts),
then stop the lathe with the tool still in the land.

Watching carefully, you can stop in a land barely more than one
thread pitch
wide.

If you don't have a threading dial, be right quick on the
cross-feed, and
back the tool out rapidly when it hits the land. Then stop the
lathe,
reverse, etc.,etc..

Thanks. What about simply reversing the lathe, would that not keep the
bit exactly where it needs to be on the thread?

i
NO!
Backlash will have it all over the place.
Ken.

Shut the lathe off early and let it cruise to near the end of the threading
section and finally move it by hand to the proper stopping point.
That's one way to do the job.

--
Why isn't there an Ozone Hole at the NORTH Pole?

On 23 May 2005 14:37:15 GMT, Ignoramus25487
wrote:

I am still trying to identify my lathe pictured at

http://igor.chudov.com/projects/clausing/01-home/

specifically:

http://igor.chudov.com/projects/clau...e/dscf0014.jpg
http://igor.chudov.com/projects/clau...e/dscf0015.jpg
http://igor.chudov.com/projects/clau...e/dscf0016.jpg
http://igor.chudov.com/projects/clau...e/dscf0017.jpg

It is likely Clausing Mk something.

I tried threading a 3/4" shaft with it recently.

My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

What is the standard approach to this problem.

i
Stopping? Why are you stopping during threading? Blink blink?

You put a long shank dial indicator on the ways below or next to the
headstock, and when you reach where you want to be..you disengage the
half nut handle, back off the compound two turns, hand feed back to
the hard stop you put to start from, and repeat as needed. The spindle
never gets shut off until you are ready to remove the work from the
chuck.

Threading up to a shoulder is nearly ...nearly impossible with these
types of lathes, but you should be able to come pretty darned close if
you are turning slow enough. Always plan for a bit of relief at the
end of your thread if running up to a shoulder.

Gunner

"Considering the events of recent years,
the world has a long way to go to regain
its credibility and reputation with the US."
unknown

On Mon, 23 May 2005 09:01:20 -0700, "Bob May"
wrote:

Shut the lathe off early and let it cruise to near the end of the threading
section and finally move it by hand to the proper stopping point.
That's one way to do the job.

I know one fella who made a crank that gets shoved into the spindle
from the backside just for this purpose. Does the last few turns by
hand, thus stopping at any given point is a snap.

On Mon, 23 May 2005 18:21:42 GMT, Gunner
wrote:

On 23 May 2005 14:37:15 GMT, Ignoramus25487
wrote:

I am still trying to identify my lathe pictured at

http://igor.chudov.com/projects/clausing/01-home/

specifically:

http://igor.chudov.com/projects/clau...e/dscf0014.jpg
http://igor.chudov.com/projects/clau...e/dscf0015.jpg
http://igor.chudov.com/projects/clau...e/dscf0016.jpg
http://igor.chudov.com/projects/clau...e/dscf0017.jpg

It is likely Clausing Mk something.

I tried threading a 3/4" shaft with it recently.

My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

What is the standard approach to this problem.

i
Stopping? Why are you stopping during threading? Blink blink?

You put a long shank dial indicator on the ways below or next to the
headstock, and when you reach where you want to be..you disengage the
half nut handle, back off the compound two turns, hand feed back to
the hard stop you put to start from, and repeat as needed. The spindle
never gets shut off until you are ready to remove the work from the
chuck.

Threading up to a shoulder is nearly ...nearly impossible with these
types of lathes, but you should be able to come pretty darned close if
you are turning slow enough. Always plan for a bit of relief at the
end of your thread if running up to a shoulder.

Gunner

Cuz' a lot of the 3-in-1's like my older Smithy don' have half-nuts
and cant be retro'd so its not an option.

snip
My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.
What is the standard approach to this problem.
================================================== ===============
Standard US practice is to simultaneously withdraw the tool using
the cross slide and snap the half nut out of engagement with the
lead screw. This required a good deal of practice and
concentration.

The longitudinal slide is then cranked back to the starting
position, the cross slide cranked back to its starting position
[a thread stop is very hand here] and the cut deepened with the
compound [top slide in the UK] set at ½ the included thread
angle. This puts the cutting almost entirely on the tailstock
side of the cutting tool [assuming a RH thread]. This avoids a
very wide chip that tends to result in chatter and having two
chips meeting in the center of the tool causing jams. This also
gives the affect of positive rake because you are moving into the
work toward the headstock. Some very good machinists suggest
setting the compound slide a few degrees less than ½ the included
thread angle to give a burnishing action to the side of the
thread away from the headstock and the added contact is stated to
reduce chatter. I have not found this necessary.

There is an accessory [actually a necessity] called a "thread
indicator" which is a small gear that engages the lead screw.
The gear turns a dial with a number of lines that indicate the
position of the half-nut relative to the lead screw. Pick any
one of the moving lines and snap the half nut in when the fixed
and moving index marks are aligned. I suggest using a magic
marker to highlight which moving line you are using.

Note: This works as long as you are using an inch leadscrew to
cut inch threads or a metric leadscrew to cut metric threads.

I suggest that you buy some of the older lathe books such as
Milne's Machine Shop Methods [c.1944] see
http://www.lindsaybks.com/bks/milne/index.html
The Sheldon lathe manual also from Lindsay is also very good.

If you will send me an email with a valid address, I will send
you a scan in pdf of the section of an atlas craftsman lathe
manual that covers threading.

Hope this helps.

"Gunner" wrote in message
...
On 23 May 2005 14:37:15 GMT, Ignoramus25487
wrote:

My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

Stopping? Why are you stopping during threading? Blink blink?

Perhaps the most common reason (for those of us with half-nuts on our
lathes) is the cutting of metric threads (which account for 95% of my
threading operations).

- Michael

The Sheldon lathe manual also from Lindsay is also very good.

Which would that be? Someone here was looking for a Sheldon manual.
I did not see it on Lindsey's site.

Rex

On Mon, 23 May 2005 15:47:11 -0500, Rex B wrote:
The Sheldon lathe manual also from Lindsay is also very good.
Which would that be? Someone here was looking for a Sheldon manual.
I did not see it on Lindsey's site.
Rex
==============
Lindsay's web site is somewhat tricky to navigate as the
hyperlinks are not clear [at least to me]
From home
click on great machine shop books
the machine shop
then running a regal lathe
at the bottom of the first [real] paragraph you can click on how
to run a southbend lathe ... and another page with the
Sheldon, southbend and Colvin info will come up.

If you don't want to go through all of this see
http://www.lindsaybks.com/bks/lathebk/index.html

I have all three of these books and they are well worth the
money.

Very good.

Did you catch that, Al?

- -
Rex Burkheimer
WM Automotive
Fort Worth TX

F. George McDuffee wrote:
On Mon, 23 May 2005 15:47:11 -0500, Rex B wrote:

The Sheldon lathe manual also from Lindsay is also very good.

Which would that be? Someone here was looking for a Sheldon manual.
I did not see it on Lindsey's site.
Rex

==============
Lindsay's web site is somewhat tricky to navigate as the
hyperlinks are not clear [at least to me]
From home
click on great machine shop books
the machine shop
then running a regal lathe
at the bottom of the first [real] paragraph you can click on how
to run a southbend lathe ... and another page with the
Sheldon, southbend and Colvin info will come up.

If you don't want to go through all of this see
http://www.lindsaybks.com/bks/lathebk/index.html

I have all three of these books and they are well worth the
money.

On Mon, 23 May 2005 16:04:01 -0400, LP
wrote:

On Mon, 23 May 2005 18:21:42 GMT, Gunner
wrote:

On 23 May 2005 14:37:15 GMT, Ignoramus25487
wrote:

I am still trying to identify my lathe pictured at

http://igor.chudov.com/projects/clausing/01-home/

specifically:

http://igor.chudov.com/projects/clau...e/dscf0014.jpg
http://igor.chudov.com/projects/clau...e/dscf0015.jpg
http://igor.chudov.com/projects/clau...e/dscf0016.jpg
http://igor.chudov.com/projects/clau...e/dscf0017.jpg

It is likely Clausing Mk something.

I tried threading a 3/4" shaft with it recently.

My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

What is the standard approach to this problem.

i
Stopping? Why are you stopping during threading? Blink blink?

You put a long shank dial indicator on the ways below or next to the
headstock, and when you reach where you want to be..you disengage the
half nut handle, back off the compound two turns, hand feed back to
the hard stop you put to start from, and repeat as needed. The spindle
never gets shut off until you are ready to remove the work from the
chuck.

Threading up to a shoulder is nearly ...nearly impossible with these
types of lathes, but you should be able to come pretty darned close if
you are turning slow enough. Always plan for a bit of relief at the
end of your thread if running up to a shoulder.

Gunner

Cuz' a lot of the 3-in-1's like my older Smithy don' have half-nuts
and cant be retro'd so its not an option.

I thought we were talking about real lathes?

Gunner, ducking and running

"Considering the events of recent years,
the world has a long way to go to regain
its credibility and reputation with the US."
unknown

On Mon, 23 May 2005 20:37:33 GMT, "DeepDiver"
wrote:

"Gunner" wrote in message
.. .
On 23 May 2005 14:37:15 GMT, Ignoramus25487
wrote:

My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

Stopping? Why are you stopping during threading? Blink blink?

Perhaps the most common reason (for those of us with half-nuts on our
lathes) is the cutting of metric threads (which account for 95% of my
threading operations).

- Michael

Metric???? Only them damned furriners use that Metric stuff.
When I want to do metric..I simply change that little knob on the
HLV-H to metric.

G

Gunner

"Considering the events of recent years,
the world has a long way to go to regain
its credibility and reputation with the US."
unknown

That lathe looks like a *******ised version of a a Clausing Model 106, which
had 17" between centers. The carriage/apron and headstock look the same but
the QC gear box is different than what I see in an old brochure. The QC
difference I see could just be camera angle & perspective, though.

Apparently some (all?) the Model 100 series lathes came with a friction
clutch/brake, which could certainly be useful to you.

You really ought to spend a few bucks and get a manual from Clausing. It
would probably run you $10 to $25, plus postage.

Mike

"Ignoramus25487" wrote in message
...
I am still trying to identify my lathe pictured at

http://igor.chudov.com/projects/clausing/01-home/

specifically:

http://igor.chudov.com/projects/clau...e/dscf0014.jpg
http://igor.chudov.com/projects/clau...e/dscf0015.jpg
http://igor.chudov.com/projects/clau...e/dscf0016.jpg
http://igor.chudov.com/projects/clau...e/dscf0017.jpg

It is likely Clausing Mk something.

I tried threading a 3/4" shaft with it recently.

My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

What is the standard approach to this problem.

i

On Mon, 23 May 2005 16:51:51 -0500, Rex B wrote:

Very good.

Did you catch that, Al?

- -
Rex Burkheimer
WM Automotive
Fort Worth TX

I did Rex, thank you!

AL

In article ,
Ignoramus25487 wrote:

I am still trying to identify my lathe pictured at

http://igor.chudov.com/projects/clausing/01-home/

specifically:

http://igor.chudov.com/projects/clau...e/dscf0014.jpg
http://igor.chudov.com/projects/clau...e/dscf0015.jpg
http://igor.chudov.com/projects/clau...e/dscf0016.jpg
http://igor.chudov.com/projects/clau...e/dscf0017.jpg

It is likely Clausing Mk something.

I tried threading a 3/4" shaft with it recently.

My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.

What is the standard approach to this problem.

i

Set your cross slide so that the crank is oriented in a way that
mashing down on the handle will back the tool out. Once you get to
where you need to stop, spin the cross slide handle a couple of turns to
back the tool off. While you're backing out the tool (or after it's
backed out) disengage the half nuts. If you consistently come to your
zero mark from one direction every time you should place the tool in the
same physical location each time with no backlash errors.
I was told that I should do both actions (back out and disengage half
nuts) simultaneously, but I found that to be a pain to get right
consistently and disengaging the half nut before backing out tended to
break tools in later passes, whereas the other way around did no damage
and terminated the thread aesthetically. So, for me, it's back out the
cross feed, then disengage the half nuts, reposition everything for the
next pass. Repeat until done.
The lathe I learned with also had to coast to a stop, and when in low
gears it could literally take a minute or so to come to a halt. I just
kept it running throughout the threading process.

--
B.B. --I am not a goat! thegoat4 at airmail dot net
http://web2.airmail.net/thegoat4/