The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this.

i

In article ,
Ignoramus25542 wrote:

The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. How much backlash does the closed half-nut
have? (This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe Gwinn

Joseph Gwinn fired this volley in news:joegwinn-
:

In article ,
Ignoramus25542 wrote:
....
If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. How much backlash does the closed half-nut
have? (This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe Gwinn


Iggy, odds are you'll find almost no thread at all in the half-nuts. As
they become severely worn, the will tend to "hop" out of engagement.
There's only one solution -- replace them; if you're really in a pinch,
you can re-make the parts, but I'd look for replacements first.

LLoyd

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
.70...
Joseph Gwinn fired this volley in news:joegwinn-
:

In article ,
Ignoramus25542 wrote:
...
If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. How much backlash does the closed half-nut
have? (This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe Gwinn


Iggy, odds are you'll find almost no thread at all in the half-nuts. As
they become severely worn, the will tend to "hop" out of engagement.
There's only one solution -- replace them; if you're really in a pinch,
you can re-make the parts, but I'd look for replacements first.

LLoyd

And one additional point: If it does come down to making the replacements,
and you have to make them on the same lathe, MAKE THEM NOW! Once the
half-nuts won't hold engagement at all, you're screwed.

--
Ed Huntress

On Feb 4, 8:11*am, Ignoramus25542 ignoramus25...@NOSPAM.
25542.invalid wrote:
The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this.

i

First things first. Have you ever cleaned them? I've seen half nuts
pack up with swarf and gummy oil so much that they would not engage
fully. A good cleaning may make them almost as good as new. Or not.

John Martin

On 2010-02-04, Joseph Gwinn wrote:
In article ,
Ignoramus25542 wrote:

The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. How much backlash does the closed half-nut
have? (This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe... Thanks... I called Clausing and talked to Tito. He told me to
first clean the leadscrew very well and check the wear on slots of the
round slotted circle that closes half nuts.

This leadscrew proved exceptionally difficult to clean, in fact, I may
just take it off and use a powerwasher or take it to a hot shower. I
spent a lot of time cleaning it and it is still not as clean as it
should be.

The half nuts are $100 from Clausing, so even if they are bad, it is
not the end of the world.

i

On 2010-02-04, Ed Huntress wrote:

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
.70...
Joseph Gwinn fired this volley in news:joegwinn-
:

In article ,
Ignoramus25542 wrote:
...
If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. How much backlash does the closed half-nut
have? (This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe Gwinn


Iggy, odds are you'll find almost no thread at all in the half-nuts. As
they become severely worn, the will tend to "hop" out of engagement.
There's only one solution -- replace them; if you're really in a pinch,
you can re-make the parts, but I'd look for replacements first.

LLoyd

And one additional point: If it does come down to making the replacements,
and you have to make them on the same lathe, MAKE THEM NOW! Once the
half-nuts won't hold engagement at all, you're screwed.


A few points of note.

1) New half nuts are $100 from Clausing (and I think they include a
new slotted circle for engaging them)
2) I have an extra pair of worn half nuts that came with the lathe
3) I think that you guys are right, I will try to take off the
carriage and apron and look at half nuts. Taking that stuff off will
be beneficial in other ways, such as cleaning the sliding surface,
etc.

"Ignoramus25542" wrote in message
...
On 2010-02-04, Joseph Gwinn wrote:
In article ,
Ignoramus25542 wrote:

The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. How much backlash does the closed half-nut
have? (This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe... Thanks... I called Clausing and talked to Tito. He told me to
first clean the leadscrew very well and check the wear on slots of the
round slotted circle that closes half nuts.

This leadscrew proved exceptionally difficult to clean, in fact, I may
just take it off and use a powerwasher or take it to a hot shower. I
spent a lot of time cleaning it and it is still not as clean as it
should be.

If you have the lathe running, set it to a slow speed/feedrate and wrap a
piece of heavy cotton cord ONCE ONLY around a groove in the leadscrew at one
end; pull hard on the cord; traverse the cord to the other end.

Soaking it in paint thinner, or, in a pinch, WD-40, will help clean out a
lot of gunk.



The half nuts are $100 from Clausing, so even if they are bad, it is
not the end of the world.

i

"Ignoramus25542" wrote in message
...
On 2010-02-04, Ed Huntress wrote:

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
.70...
Joseph Gwinn fired this volley in news:joegwinn-
:

In article ,
Ignoramus25542 wrote:
...
If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. How much backlash does the closed half-nut
have? (This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe Gwinn


Iggy, odds are you'll find almost no thread at all in the half-nuts. As
they become severely worn, the will tend to "hop" out of engagement.
There's only one solution -- replace them; if you're really in a pinch,
you can re-make the parts, but I'd look for replacements first.

LLoyd

And one additional point: If it does come down to making the
replacements,
and you have to make them on the same lathe, MAKE THEM NOW! Once the
half-nuts won't hold engagement at all, you're screwed.


A few points of note.

1) New half nuts are $100 from Clausing (and I think they include a
new slotted circle for engaging them)
2) I have an extra pair of worn half nuts that came with the lathe
3) I think that you guys are right, I will try to take off the
carriage and apron and look at half nuts. Taking that stuff off will
be beneficial in other ways, such as cleaning the sliding surface,
etc.

And look for settled gunk in the apron.

--
Ed Huntress

On 2010-02-04, Ed Huntress wrote:

And look for settled gunk in the apron.


Regarding taking off apron: I did try this once.

It did not work: the "carriage locking screw" would not unscrew all
the way.

I did not want to force it and I had other issues, so I gave up and
moved on to other things, but now is the time to look at it.

The carriage locking screw connects to a plate under the carriage, so
that when you tighten it it grabs the bed.

The screw unscrews, but stops midway and I wanted to know if I am
doing something wrong or should just use a bit more force.

i

"Ignoramus25542" wrote in message
...
On 2010-02-04, Ed Huntress wrote:

And look for settled gunk in the apron.


Regarding taking off apron: I did try this once.

It did not work: the "carriage locking screw" would not unscrew all
the way.

I did not want to force it and I had other issues, so I gave up and
moved on to other things, but now is the time to look at it.

The carriage locking screw connects to a plate under the carriage, so
that when you tighten it it grabs the bed.

The screw unscrews, but stops midway and I wanted to know if I am
doing something wrong or should just use a bit more force.

i

Good question. I hope someone who knows your lathe can give you an answer,
because it would be a bugger to strip a special screw trying to find out.

--
Ed Huntress

On Feb 4, 11:29*am, "Ed Huntress" wrote:
"Ignoramus25542" wrote in message

...



On 2010-02-04, Joseph Gwinn wrote:
In article ,
*Ignoramus25542 wrote:

The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. *How much backlash does the closed half-nut
have? *(This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe... Thanks... I called Clausing and talked to Tito. He told me to
first clean the leadscrew very well and check the wear on slots of the
round slotted circle that closes half nuts.

This leadscrew proved exceptionally difficult to clean, in fact, I may
just take it off and use a powerwasher or take it to a hot shower. I
spent a lot of time cleaning it and it is still not as clean as it
should be.

If you have the lathe running, set it to a slow speed/feedrate and wrap a
piece of heavy cotton cord ONCE ONLY around a groove in the leadscrew at one
end; pull hard on the cord; traverse the cord to the other end.

Soaking it in paint thinner, or, in a pinch, WD-40, will help clean out a
lot of gunk.



The half nuts are $100 from Clausing, so even if they are bad, it is
not the end of the world.

i

AND DON"T WRAP THE CORD AROUND EITHER HAND!!

Attaching the cord ends to the end of a board and holding the board
would add a safety factor, and let you pull harder.



Dave

John Martin wrote:
On Feb 4, 8:11 am, Ignoramus25542 ignoramus25...@NOSPAM.
25542.invalid wrote:
The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this.

i

First things first. Have you ever cleaned them? I've seen half nuts
pack up with swarf and gummy oil so much that they would not engage
fully. A good cleaning may make them almost as good as new. Or not.

John Martin

The half nuts on my Wards/Logan were gunked like that . Crud between the
halves blocked them closing all the way . Makes 'em wear faster too .

--
Snag
New ones for mine were
about the same price .

Ignoramus25542 wrote:

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this.


If your half nuts are in good shape, crap/chips embedded in the half nuts.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

"Ed Huntress" wrote:


If you have the lathe running, set it to a slow speed/feedrate and wrap a
piece of heavy cotton cord ONCE ONLY around a groove in the leadscrew at one
end; pull hard on the cord; traverse the cord to the other end.

Soaking it in paint thinner, or, in a pinch, WD-40, will help clean out a
lot of gunk.


That is an excellent suggestion! Btw, if you haven't seen his model of lathe, it has a
rather fine pitched lead screw so a bit of dirt is a lot of dirt.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

"Wes" wrote in message
...
"Ed Huntress" wrote:


If you have the lathe running, set it to a slow speed/feedrate and wrap a
piece of heavy cotton cord ONCE ONLY around a groove in the leadscrew at
one
end; pull hard on the cord; traverse the cord to the other end.

Soaking it in paint thinner, or, in a pinch, WD-40, will help clean out a
lot of gunk.


That is an excellent suggestion!

An old, old trick. g

Btw, if you haven't seen his model of lathe, it has a
rather fine pitched lead screw so a bit of dirt is a lot of dirt.

Wes

I don't remember it, but that would make it even more suitable. That's how I
clean the screw on my SB.

--
Ed Huntress

"Ed Huntress" wrote:

That is an excellent suggestion!

An old, old trick. g

I know, and I've heard it before but the other day when I looked at my screw that is the
same only other then shorter, I couldn't remember that trick for cleaning.

I guess you win the been around long enough to know that one award. No monetary value.

Btw, if you haven't seen his model of lathe, it has a
rather fine pitched lead screw so a bit of dirt is a lot of dirt.


I don't remember it, but that would make it even more suitable. That's how I
clean the screw on my SB.

That is going to be my way on my lathe also.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

Ignoramus25542 wrote:
The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this.
Classic case of worn half-nuts. But, take the whole mechanism
apart, there may have been a detent mechanism that has gotten
gummed up or worn. If not that, then it is likely due to wear
of the half-nut threads that are now pushing the nuts apart.
It could also be a misalignment of the nuts to the leadscrew,
swarf packed into the half nuts preventing them from fully closing
or something like that.

Jon

Ignoramus25542 wrote:
On 2010-02-04, Ed Huntress wrote:
And look for settled gunk in the apron.


Regarding taking off apron: I did try this once.

It did not work: the "carriage locking screw" would not unscrew all
the way.

I did not want to force it and I had other issues, so I gave up and
moved on to other things, but now is the time to look at it.

The carriage locking screw connects to a plate under the carriage, so
that when you tighten it it grabs the bed.

The screw unscrews, but stops midway and I wanted to know if I am
doing something wrong or should just use a bit more force.
Geez, I'm not sure. Is this a classic Atlas, or a Clausing industrial
lathe? I know the Atlas pretty well, I'm the moderator of the
Atlas-Craftsman group on Yahoo. I wouldn't be too surprised if
there is something to prevent the clamp plate from completely unscrewing
and falling into the half-nut mechanism. I don't think the Atlas had
such a protection. Anyway, you should be able to run the carriage at
least partly off the right end of the bed to examine the parts. Take
the tailstock off and then remove the right-end leadscrew bracket.

Jon

Ignoramus25542 wrote:

This leadscrew proved exceptionally difficult to clean, in fact, I may
just take it off and use a powerwasher or take it to a hot shower. I
spent a lot of time cleaning it and it is still not as clean as it
should be.

One trick is to grind a small screwdriver or similar piece to match the
thread, and then run the lathe at low speed and hold the tool in the
groove. A keyed Acme screw is a little harder to clean this way, but it
definitely works. If swarf is packed totally hard in the screw, water
won't get it out, anyway, and that is likely part of the threading
trouble. If the screw is packed with rammed-in chips, the nuts will
be worse!

Jon

Ed Huntress wrote:

Btw, if you haven't seen his model of lathe, it has a
rather fine pitched lead screw so a bit of dirt is a lot of dirt.
Hmm? It would almost have to be either 8 or 16 TPI for Imperial
thread pitches.

Jon

On 2010-02-04, Ignoramus25542 wrote:
The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this.

I can think a few possible causes:

1) A large chip embedded in the Acme thread of the leadscrew (or
the long key groove used to power the power feed in some
machines).

2) A bent leadscrew, bumping the half-nuts open.

3) Badly worn half-nut threads. (It is possible to
cast new ones in Babbit metal.)

4) Missing detent spring in the half-nuts lever assembly.

5) Is the interlock between the half-nut lever and the power
feed lever working properly? It should not be possible to
engage both at the same time. Each should lock out the other.

Good Luck,
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 ---

On Feb 4, 7:39*pm, "DoN. Nichols" wrote:
On 2010-02-04, Ignoramus25542 wrote:

The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this.

* * * * I can think a few possible causes:

1) * * *A large chip embedded in the Acme thread of the leadscrew (or
* * * * the long key groove used to power the power feed in some
* * * * machines).

2) * * *A bent leadscrew, bumping the half-nuts open.

3) * * *Badly worn half-nut threads. *(It is possible to
* * * * cast new ones in Babbit metal.)

4) * * *Missing detent spring in the half-nuts lever assembly.

5) * * *Is the interlock between the half-nut lever and the power
* * * * feed lever working properly? *It should not be possible to
* * * * engage both at the same time. *Each should lock out the other.

* * * * Good Luck,
* * * * * * * * 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 ---


I found that a tooth brush is pretty good for cleaning the lead
screw. Just hold it against the screw at an angle. If the crap is
packed really tight in the (fine) threads a brass brush would be
better. Don't think I'd use a steel implement to run in the threads.

My olde 6" Atlas would develop a similar symptom and it turned out to
be crap collected in the threads thereof.

A good cleaning and oiling and we were good to go.

As Jon wrote above, On this lathe the whole carriage can be removed
by sliding it off the right hand end off the bed. Only had to remove
the lead screw bearing to to this.

Wolfgang

"Jon Elson" wrote in message
...
Ignoramus25542 wrote:
On 2010-02-04, Ed Huntress wrote:
And look for settled gunk in the apron.


Regarding taking off apron: I did try this once. It did not work: the
"carriage locking screw" would not unscrew all
the way. I did not want to force it and I had other issues, so I gave up
and
moved on to other things, but now is the time to look at it. The carriage
locking screw connects to a plate under the carriage, so
that when you tighten it it grabs the bed. The screw unscrews, but stops
midway and I wanted to know if I am
doing something wrong or should just use a bit more force.
Geez, I'm not sure. Is this a classic Atlas, or a Clausing industrial
lathe? I know the Atlas pretty well, I'm the moderator of the
Atlas-Craftsman group on Yahoo. I wouldn't be too surprised if
there is something to prevent the clamp plate from completely unscrewing
and falling into the half-nut mechanism. I don't think the Atlas had such
a protection. Anyway, you should be able to run the carriage at
least partly off the right end of the bed to examine the parts. Take the
tailstock off and then remove the right-end leadscrew bracket.

Jon

My Atlas 1/2nuts always are disconnecting from the drive screw. What should
I look at there?

In article ,
Ignoramus25542 wrote:

On 2010-02-04, Ed Huntress wrote:

And look for settled gunk in the apron.


Regarding taking off apron: I did try this once.

It did not work: the "carriage locking screw" would not unscrew all
the way.

I did not want to force it and I had other issues, so I gave up and
moved on to other things, but now is the time to look at it.

The carriage locking screw connects to a plate under the carriage, so
that when you tighten it it grabs the bed.

The screw unscrews, but stops midway and I wanted to know if I am
doing something wrong or should just use a bit more force.

I took mine apart and cleaned it without difficulty. It was very dirty.
The carriage clamp bolt just unscrewed, so I bet that you are being
blocked by some spooge on the ordinarily unused part of the bolt thread.
Do not try to force it, at least not initially. Instead, use a scriber
or pick to break the deposits up first. Soaking with acetone also helps
a lot, as does ordinary methylene chloride based paint stripper. Once
the bulk deposits are removed, a little force is OK - the parts are all
made of steel.

I just looked at the manuals for 5900 and 6900 series lathes. The
carriage clamps are identical, as shown on page 31 (pdf page 38) of the
6900 series manual. It's just a bolt screwing into a block.

Joe Gwinn

Bill McKee wrote:

My Atlas 1/2nuts always are disconnecting from the drive screw. What should
I look at there?



First, clean the screw and nuts and associated mechanism. You may need
an awl or something to pick the most stubborn bits of swarf out of the
teeth. If the half nuts or the cam that engages them are badly worn,
there may not be much you can do to help them. If you have a 3/4"
leadscrew, replacement parts are available from the Clausing Service
Center for what seems a reasonable price. If the leadscrew is bent, it
need to be straightened. Also check that the leadscrew is running
through the center line of the nuts. if the bed has been ground or
something it might be off-center.

My recollection is now hazy, but I seem to recall a detent ball and
spring that helps retain the cam and engagement handle in position.
So you can check the condition of that.

If the teeth of the nuts are worn very much, they form a ramp that
drives the nuts apart. Also, a really badly worn leadscrew can get
the same way. The only hope there is replacement.

Jon