leadscrew nut re taper attachment

[petertha]

I took a picture of how my lead screw nut sits relative to the cross slide as a preamble to my question. The nut has a vertical extended tab protrusion that positions into a matching notch of the cylindrical fitting. That fitting resides in the cross slide, appears to be a press fit, I couldn’t push it out with finger pressure. The leadscrew nut is retained in the fitting slot by a cap screw, then assembly gets aligned on the dovetails, nut engaged on lead screw & screwed on. Then a washer bolt on the end of the lead screw as a stop, then the gib strip adjusted.

I don’t have a taper attachment on this lathe & now I think I understand why it was required to be specified upon order on my particular brand. (And I chose wrong!).

Even if I had the taper attachment business installed, it could freely not push the cross slide as-is with nut engaged. I could tear down the lathe to this level, remove the nut, re-assemble thus leaving cross-slide free to slide. Bu that’s a huge pain.

Now I’m wondering out loud, could I somehow modify this system so that if I undid the capscrew, the nut was no longer engaged? Idea-1: I thought the nut could rotate so that its tab part was no longer ‘up’. But doesn’t look like enough room in the casting trough to rotate enough. Idea-2: if that cylindrical bolt plug thing could be slid up & out of the cross-slide enough, then it’s extending notch is out of the way & nut would not engage it? But maybe it is a press fit to ensure tight leadscrew action? If it was a slip fit I would lose accuracy?

Whew! Any comments or pics of how other lathes deal with this issue as an example?

[Brian]

Hi

On my lathe I remove the feed screw from the front, leaving the nut in place.

Brian.

[Mayhem]

Removing the cross slide screw, as described by Brian, was the way that I understood taper attachments to be used.

It is certainly an easier task than removing the nut.

[petertha]

>Removing the cross slide screw...

I was wondering that too, possibly removing bolts (5) & collar (7) & uncrewing out. The handle & graduation dial & detant ball/spring thingy has to come off first, it seems similar to the compound assembly I took apart. But mostly I'm concerned about the bearing cluster staying intact with the assembly & didnt want to mess with that if I didnt have to.

They show that cylindrical part (77) I was referring to seperately but maybe it just for illustration purposes. I think its pressed in & supposed to stay put. That seemed like the easiest thing to focus on. If it was temporarily up & out of the way with cao screw removed, the leadscrew nut would no longer be engaged to the table & it would slide

[TomG]

On my lathe, I just remove the screw that attaches the cross slide to the nut to use the taper attachment. Making the tab on your nut a slip fit shouldn't hurt anything since the screw locks it down anyway. The only possible purpose I can see for it would be to keep the nut from rotating when the screw is tightened, but that seems like over engineering to me since the lead screw does the same thing.

Tom

[petertha]

Interesting. I looked at the parts sketch for the current King 14x40 lathe model. There appears to be no vertical tab on the lead screw nut, just retained with the bolt as you say.

[stevec]

(10-24-2012, 09:57 AM)petertha Wrote: >Removing the cross slide screw...
But mostly I'm concerned about the bearing cluster staying intact with the assembly & didnt want to mess with that if I didnt have to.

If by bearing cluster you are referring to the 2 #6s on either side of #7. I don't think yoneed to worry they should be thrust races with a caged ball thrust in between them and once The capscrews have been removed from #7 you should be able to slip the handwheel back on and just wind the whole assembly out of the cross slide nut.
Unless I'm missing something.

[stevec]

I think the "tab" (which I would call a key) is a good thing and wouldn't recommend filing or milling it off.
Just my take.

[TomG]

Just to add, I wouldn't remove the tab because it would help with extreme pressure situations like knurling, but there is no reason why it would need to be a tight fit in the slot.

Tom

[EdK]

(10-24-2012, 01:50 PM)stevec Wrote:

(10-24-2012, 09:57 AM)petertha Wrote: >Removing the cross slide screw...
But mostly I'm concerned about the bearing cluster staying intact with the assembly & didnt want to mess with that if I didnt have to.

If by bearing cluster you are referring to the 2 #6s on either side of #7. I don't think yoneed to worry they should be thrust races with a caged ball thrust in between them and once The capscrews have been removed from #7 you should be able to slip the handwheel back on and just wind the whole assembly out of the cross slide nut.
Unless I'm missing something.

You're not missing anything Steve. Or we both are.

Ed