1938 SB 9C leadscrew play

Manual Mac

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I’m trying to remove play (.006) on the leadscrew on my SB 9C.
The play is where the large collar on the leadscrew abuts the front bracket.
Other than making a shim I do not see any adjustment?
Any ideas?
 
I think there is an adjustment nut(s) inside the change box, I also have one that is loose and needs adjustment. If you can find a parts list online, it should show this detail.
 
Doing a bit of research, I see that the model C is the loose change gear machine,m while mine is a model A; on it, visible with a mirror are 2 locknuts in the change box, on the model C there is a nut on the end of the lead screw, whether it is capable of adjustment, I do not know, you may just have to make a new thrust washer to remove (most) of the end play. A small amount of end play is not generally a problem in operation.
 
Thanks benmychree for the reply’s.
.006 side play does not sound like much and it isn’t if cutting coarse threads or or taking heavier cuts.
Where it is problematic is very fine threads or fine feeds where it kinda stops for a moment (in mid thread or feed) for slack to take up then resumes feed. I don’t know how to dial out this slack, it just happens intermittently. Do not know why.
To be fair, this is an old lathe with MUCH use.
I think .006 or .007 thrust washer shim is in my future.
Then all should be good again.
Thanks, Steve
 
I was taught in school to put a slight drag on the carriage handwheel with my fingers to smooth things out, it is likely the unbalanced handwheel causing the problem as it flops over its out of balance center.
 
The hand on the hand wheel is the recommended fix.
I had end play in my Clausing lathe’s lead-screw and I did make a shim for it. Tried 5 thousandths Brass shim Stock first but it was just too much trouble to punch a hole in it without distorting the brass so I made a delrin washer. It’s held up just fine and did the trick. I’m actually not sure if it was a need to do repair....but it’s done now and it’s staying there. Not worth overthinking this stuff.

I honestly don’t remember even paying attention to see if my 9” SB has the same issue. I’ll have to check that....;)
 
As a follow-up to this problem, it appears I was chasing a red herring.
The .006 side play in the leadscrew had nothing to do with anything.
In my anal quest to get the backlash out of the change-gear train, something was a little tight & would bind intermittently, causing the leadscrew to move.
Loosened up all the gears, problem solved. My Bad.
And I just installed the rebuilt halfnuts, (thanks Jawhawkman) & all is good now.
Sorry about the confusion.
 
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