I have a venerable 1949 South Bend 9" lathe. Sadly, its cross-slide nut (or
screw, or both) have a fair amount of wear, as I can grab the cross-slide table
and move it nearly 1/16" with my hands. I'm whittling down a block of 303
stainless and it seems like it's taking forever. The machine is cutting the 303,
but I can only advance the cutter about .010" between passes, and reducing the
diameter .020" at a time is going to mean a lot of lathe work. I don't really
have to do it, of course, but it has led me to wonder if the slop in my
cross-slide screw actually contributes to lack of rigidity while turning. I have
always figured as long as the slack in the screw was taken up, it wouldn't make
any difference whether there were .004" of backlash or .040". Yet I don't have a
complete understanding so I thought I'd post this to the group. There is an
advertiser in HSM that offers new cross-slide nuts and screws for my lathe at
what seems like a reasonable price.

GWE

I recently replaced that nut on my Atlas 10" lathe. I had about the
same amount of slop. Glad I did it.
My big problem was that with all that slop, the tool could dig in at
the drop of a hat, making for inaccurate work. I guess that could easily
look like a rigidity problem.

Pete Stanaitis
-----------------

Grant Erwin wrote:
I have a venerable 1949 South Bend 9" lathe. Sadly, its cross-slide nut
(or screw, or both) have a fair amount of wear, as I can grab the
cross-slide table and move it nearly 1/16" with my hands. I'm whittling
down a block of 303 stainless and it seems like it's taking forever. The
machine is cutting the 303, but I can only advance the cutter about
.010" between passes, and reducing the diameter .020" at a time is going
to mean a lot of lathe work. I don't really have to do it, of course,
but it has led me to wonder if the slop in my cross-slide screw actually
contributes to lack of rigidity while turning. I have always figured as
long as the slack in the screw was taken up, it wouldn't make any
difference whether there were .004" of backlash or .040". Yet I don't
have a complete understanding so I thought I'd post this to the group.
There is an advertiser in HSM that offers new cross-slide nuts and
screws for my lathe at what seems like a reasonable price.

GWE

All lathes unless equipped with ball screws have backlash in the crossslide
& compound screws. While turning there is continous pressure against the
tool so backlash really doesn't matter, assuming your tool is above or at
center. If you let your tool below center it can get dragged into the work,
for instance when parting off.

I wouldn't worry about it unless the backlash is more than 3/4 of a turn, &
then only because it becomes difficult to remember where the correct reading
is when approaching the surface of the work.

Rigidity comes more from the snuggness of your gibs.

Tony

"Grant Erwin" wrote in message
...
I have a venerable 1949 South Bend 9" lathe. Sadly, its cross-slide nut
(or
screw, or both) have a fair amount of wear, as I can grab the cross-slide
table
and move it nearly 1/16" with my hands. I'm whittling down a block of 303
stainless and it seems like it's taking forever. The machine is cutting
the 303,
but I can only advance the cutter about .010" between passes, and reducing
the
diameter .020" at a time is going to mean a lot of lathe work. I don't
really
have to do it, of course, but it has led me to wonder if the slop in my
cross-slide screw actually contributes to lack of rigidity while turning.
I have
always figured as long as the slack in the screw was taken up, it wouldn't
make
any difference whether there were .004" of backlash or .040". Yet I don't
have a
complete understanding so I thought I'd post this to the group. There is
an
advertiser in HSM that offers new cross-slide nuts and screws for my lathe
at
what seems like a reasonable price.

GWE

Grant Erwin wrote:

I have a venerable 1949 South Bend 9" lathe. Sadly, its cross-slide nut (or
screw, or both) have a fair amount of wear, as I can grab the cross-slide table
and move it nearly 1/16" with my hands. I'm whittling down a block of 303
stainless and it seems like it's taking forever. The machine is cutting the 303,
but I can only advance the cutter about .010" between passes, and reducing the
diameter .020" at a time is going to mean a lot of lathe work. I don't really
have to do it, of course, but it has led me to wonder if the slop in my
cross-slide screw actually contributes to lack of rigidity while turning. I have
always figured as long as the slack in the screw was taken up, it wouldn't make
any difference whether there were .004" of backlash or .040". Yet I don't have a
complete understanding so I thought I'd post this to the group. There is an
advertiser in HSM that offers new cross-slide nuts and screws for my lathe at
what seems like a reasonable price.

GWE

Use a tool that pushes toward the chuck without exerting any forward
pressure. It will work much more effectively and you will get a
strighter cut since you have a mimimum of pressure to deflect the piece.

Any loseness in the compound and cross slide will be a lot less of a
problem.




John