Threading half nuts

[rock_breaker]

Due to the long throw on my Grizzly G9295 ? lathe I was missing the mark and subsequently not producing usable threads. Grizzly service suggested tightening an adjustment screw or new half-nuts. After tightening the screw the powered feed did not engage properly, things were re-adjusted somewhat to workable and I found that threading could be done by moving the half-nut lever to near engagement position then moving the lever a much shorter distance to engage the nuts. Has anyone else encountered this problem?

 

[Tony Wells]

I can't speak to the Grizzly issue directly, but most every lathe I have run has a little "slop" in the half-nut engagement. As the chasing dial comes around, just before it aligns with the number/letter targeted, I begin to lower the engagement lever. I can feel the half-nuts riding on top of the screw, and when it drops in, I feel that and push the lever to full engagement. If you wait until the mark comes fully into alignment with the mark, it probably isn't perfectly aligned with the screw, and won't engage properly. It seems to help older lathes to run the chasing dial driven gear a little closer to the screw, taking some slack out.

 

[rock_breaker]

Thanks Tony, your procedure is what I am doing now. missed the number once so waited for it to come around again. Sorry for the delay in the response, seems like the world is moving faster each year.

Ray

 

[GK1918]

Just as Tony said they all have a sweet spot, even properly meshing thread dial, it never seems to be
perfect. So to overcome this little error, a simple big big washer with an index mark just placed over
the thread dial now engauge half nut and just dial in the washer so the witness marks line up. I did
have to turn a little off the downside of the washer for relief for the dial not to rub. Then my big lathe
has a pretty large dial and a bearing retainer painted black white witness mark works like a champ.