10k leadscrew play

Hello, I have fairly recently acquired a 10k (first lathe) that while filthy, overall appears in good to very good condition. The worst problem I've found so far is that before I began disassembly and rehab was the lead screw had a lot of longitudinal play/slop, nearing a quarter of an inch. The leadscrew gear took some damage due to this, but I've cleaned up the teeth somewhat and removed the largest burrs. However, the leadscrew itself looks very good as do the half nuts, but I noted a loose locknut in the gearbox on the end of the leadscrew. I'm finally beginning reassembly of the lathe now, and I put a new locknut on the leadscrew tonight, and noted that while the play was dramatically reduced, it was still quite a lot and I was able to get about 0.075" feeler gauges into the gap between the leadscrew shoulder and the gearbox casing (externally). There were no shims/washers present on this area at disassembly. It looks to me that the leadscrew needs to be shimmed between the casing and shoulder (outside the gearbox) for proper alignment of the gears in the box (see pics). I've ordered some round shim stock (steel) to adjust this, but wanted to make sure I was on the right path to fixing this issue, and what amount of play would be considered appropriate?

Thanks for the help.

Yep, trail on! I'd set for 5-10 thou. You'll never see that, or 50 thou for that matter, when thread cutting unless for some interesting you need to reverse the lead screw to finish the cut. That would bite....

Pete

Thanks. I checked that the lead screw gear was tight up against its shoulder in the gear box, and yes it is keyed as well. i'll get some shims going on the outside of the box to reduce the play.

See that pin...you are lucky usually you can't see it..its a taper pin, find the small end and drive it out...you can then slide that collar to take up the excess clearance and redrill for the taper pin, or use a straight pin too....but a shim will work too.

Hmm.

Why does it look like that nut is missing?

The really long threaded portion seems to be highly suspicious.

Is the bore of the gear threaded?

I agree, looks like a nut may be missing.

If I am reading this right, we need a #31 collar, a washer, and a nut.
If it were me, I'd be real sure that gear is as far onto the leadscrew as it can get. I can't imagine something getting out of the factory like that. The doc I got this from says it is for the 9 and the 10k..

yes, there is a nut, I just had it off for the pics. the lathe had a 1/2-13 nylock nut on the leadscrew which had gotten loose. I am replacing that with same, although I don't know if the nylock nut was factory or not (this is a fairly late production machine, s/n 40177K I believe). I suppose I could use a standard nut w/ spring washer if needed. the lead screw gear is completely up against it's shoulder in the pics. even with the nut tightened, it looks identical to the above. I moved the lead screw shaft left and right to show the clearance for the pics, but will have to shim externally, as otherwise they will interfere with the gears in the box. The shims should be here today. Any other ideas are welcome.

Just to update if anyone else runs into this problem. The 3/4" ID arbor shims from amazon worked well for the application, and I was able to shim to about 0.004" clearance, which was the tolerance listed in another thread on the board from several years ago. Total shim stack thickness was 0.075" (0.050 + 0.025 shims). Thanks for all the help.

Did you remove the tapered pin from the collar? I'm wondering if the tapered pin might be partially sheared?

No, that was about the only thing I didn't take apart on this lathe. I just finished reassembly yesterday but still have to install the drive arrangement (horizontal mount). Once I have it under power I can confirm it works well.