Slotted Lead Screw Question

[ShagDog]

Well I just took the cross feed lever assembly off and messed with the push rod under it. The rod just pushed in and out with a heavy spring. I turned it and no change. Put the lever assembly back on, and again confirmed that the lever only appears to operate the cross feed. Just makes no sense to me.

Bear, the lever will not move out and to the right. Looking at the Select "Part List Of Precision Bench Lathe". There is no indication of any key that would go into the leadscrew. Here is a photo of the page.

Edit: Just added a photo of the parts list also. Hopefully the photos will shed some insight.

 

[682bear]

Ok, there is only a single worm... there has to be a key in the worm or your cross feed wouldn't work, either. I would guess the key is a permanent part of the worm, so the drawing doesn't show it as being a seperate part.

I noticed that the lever that closes the half nuts is labeled as 'longitudinal feed and threading control'...

So, I guess you were correct to start with... the half nuts control the longitudinal feed.

-Bear

 

[ShagDog]

...

I noticed that the lever that closes the half nuts is labeled as 'longitudinal feed and threading control'...

So, I guess you were correct to start with... the half nuts control the longitudinal feed.

-Bear

Unfortunately, I think you are correct. Although I wasn't really sure, I really wanted to be wrong . Still makes me wonder why the slotted leadscrew.

Thanks to all that responded.

 

[682bear]

The slot in the leadscrew engages a key in the worm to drive the cross slide feed.

-Bear

 

[jcp]

From the parts breakdown it's would appear that you do have only a choice of cross feed engaged or disengaged, the half nuts providing longitudinal feed.

 

[ShagDog]

The slot in the leadscrew engages a key in the worm to drive the cross slide feed.

-Bear

I get it now . Thanks, Bear and jcp.

 

[MyLilMule]

That center lever may need to be pulled to the left and then down to allow for the half nut to be engaged.

 

[ShagDog]

That center lever may need to be pulled to the left and then down to allow for the half nut to be engaged.

Thanks; but, there is no leftward movement.

 

[MyLilMule]

I am in agreement with the others. Based on that parts diagram, it looks like your half nut is also used as a carriage feed. Your lead screw may have been replaced by a previous owner with one for a slot. Or the manufacturer made all lead screws the same, and depending on the model it was placed in, it used the keyway or not. The only way to know for sure may be to remove the apron or get a mirror to inspect behind it.