Threading Leadscrew adjustment

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Gunnermhr1

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Hi All,

Recently I've noticed an exceptional amount of end play in my threading leadscrew, I believe this is what is causing unevenness in my thread thickness. The manual doesn't show how to adjust the endplay and I really don't want to cause more damage than good. Has anyone had to make adjustments on the endplay and if so what is the best way to do it.

Thanks in advance,
Mike

20190228_062827.jpg
 
So your saying you can move the leadscrew left and right? The half nuts can be adjusted which would eliminate some backlash but it depends where the slop is at.
 
Yes, I can move the leadscrew a lot, at least what I consider a lot, maybe .050". I'll measure it tonight. If you look at the photo, the top shaft in the rear has a nut then a gear then 3 Washers, i would assume if i tighten that nut it will eliminate the end play. But I'm not sure, and if that is the way to do it i'm not sure how tight to make it?

I guess if someone could check their leadscrew for end play it might help to answer my question if that's where the issue is or if it's a half nut adjustment
 
Just tighten it up until slop is taken up, without feeling any binding; I'd have thought that likely there would be two nuts, or some way of locking the nut on the threads so as to keep things from loosening.
 
I'll give it a try! I called PM this morning, they referred me to the manual. There is no mention of adjustment for end play. I'm planning on stopping by their shop next week to grab a few things, I'll do some asking and looking while I'm there
 
When you say you have 50th slop is that the total amount the saddle wobbles if you wobble the hand wheel on the saddle ?

Normally during threading the slop is taken out as you run into the cut. Sort of like the way you manage back lash on cross slides etc.

Have you started a "whats wrong with my threads" thread yet ? Might be worth posting some pics and getting opinions.

Stu
 
If there is no convenient adjustment method, a brass or bronze washer of the appropriate thickness added on the end of the lead screw
might take out the slop.
 
Gunner so if you put your hand by the shear pin connection to the lead screw and push/pull it has play? If so then yes that should be able to be taken up by where you describe. As for how tight I would disengage as much as possible so you single out that assy. When tightening I would seat the bearing then back off a touch. Probably put a indicator on shear pin hub and check for endplay and adjust till near zero. Does the tail stock end have a bushing or bearing assy. Depending on how much you pull it in may change preload of bearing if it’s equipped with one.
 
I have a similar lathe and on mine you simply tighten that nut to take up slop. The nut on mine is a locknut instead of two nuts.

Sent from my SM-G930F using Tapatalk
 
Gunnermhr1 said:
Hi All,

Recently I've noticed an exceptional amount of end play in my threading leadscrew, I believe this is what is causing unevenness in my thread thickness. The manual doesn't show how to adjust the endplay and I really don't want to cause more damage than good. Has anyone had to make adjustments on the endplay and if so what is the best way to do it.

Thanks in advance,
Mike
Click to expand...

I agree w/ Stupoty. A small amount of end play in the lead screw will not impact thread quality. I have a 1340GT and when I started out threading I quickly learned that it is easy to partially close the half nut on the lead screw and advance the carriage through the thread pass. You mentioned the half nut adjustment. I reduced the half nut gib tension and this made closing the half nut much easier allowing me to hit the dial marks consistently. Making that adjustment was, for me, a huge improvement.

However (and this is where backlash in the lead screw will get you) if you are cutting metric threads and decide not to back out the compound (or cross slide) before reversing the spindle to run the carriage back to the start, the threading tool will not track the thread root and will ruin the work.

Let us know what you find.
 
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