In article ,
Ignoramus17831 wrote:

On 2010-03-09, Joseph Gwinn wrote:
In article ,
Ignoramus8009 wrote:

On 2010-03-09, Joseph Gwinn wrote:
In article ,
Ignoramus8009 wrote:

On 2010-03-08, Joseph Gwinn wrote:
Right. One has to wait for the leadscrew to turn to the correct
angle
for
the nut to engage. One way to do this is to watch the threading dial
and
operate the lever only when the dial says it's time. After a little
practice
this become a fluid motion.

The issue is that if I apply any significant force on the half nut
lever, the pin would bend. I just spoke to Clausing, they no longer
have those pins, but can supply drawings for $5. Since replacing them
is such a pain, I should be careful with the one I have now.

To stay safe, I may change the handle on the half nut lever, to
something very tiny that would be very difficult to force. Maybe a 1
inch long handle made of a socket head cap screw. That would be harder
to accidentally force enough to bend the internal pin. It will not
look as great, but it will keep me safe, and I will of course save the
old handle.

I would leave it alone. The guy that bent the pin was a gorilla - more
muscle
than brain.

You will find that it is not at all hard to get the half-nut engaged
without
forcing anything. You make the move just before the correct line on the
threading dial goes by. Any you don't force it -- you do it by feel.

What such a small handle would do, is protect me from my own
mistakes. Or, say, if I invite a friend over and he would try to force
the lever, that would not happen if the handle was tiny.

Developing the feel and the rhythm is critical, and a too-small lever will
interfere with this.

Ignoring the direction in which one moves the lever, pretty much all lathes
work
the same way when engaging the half nuts, and Clausings are not exactly
made of
tinfoil.

On reflection, what I suspect happened is that as the half-nuts became
packed
with chips, it became harder and harder to engage them well enough that
they
wouldn't pop out of engagement, so the level of force used rose gradually.
What
people were doing is pack layer after layer of chips into the threads,
until no
more chips would fit.

How hard would it be to disassemble and clean only the half-nut assembly?
I may
do this on my 5914. Even though I have not had any problem engaging and
disengaging the half nut, and the interlock works, I'm suspicious that
there may
be some chip packing because I did find a lot of chip packing under the
saddle,
and because the leadscrew was not exactly clean.


Joe Gwinn

I would estimate that if you go slow, on my lathe it takes 1 hour
to take apron off and one hour to put it back.

That's not that bad, although apron removal is required it seems.


New half nuts are only $100 from Clausing, I would say it is a no
brainer to get them when they are still available.

Nor is that.


With the apron and leadscrew off, you can take your time to clean the
leadscrew, etc.

I have already cleaned the leadscrew. Actually, one is supposed to clean it
once a week with kerosene, according to a manual I have.

If I do this repair, I may buy the half nut set in advance, to reduce down time.

As I continue in my educational program to become a machine tool tech.

Joe Gwinn