Sheldon EXL56 tailstock alignment issue

First, yes the lathe is level. Let's get that out of the way.


I decided to align my tailstock to dead nuts. I started by indicating from the chuck to a dead center in the tailstock that's when I saw the following: I aligned the tailstock to .000 on left and right and then as soon as I loosened the tailstock the indicator sprang .005. Ok that's to be expected, but when I tightened it back down it stayed out .005. I recentered it to .000 and loosened the tailstock and retightened, boom, exact same thing.

I have taken apart the tailstock and cleaned everything and all the lathe bed ways and it is still happening. This tailstock design doesn't have the 2 screws setup it has 1 lead screw through a threaded boss on the base.


left at 0:


right at 0:


The spring back after loosening and retightening.


Tailstock adjust screw:


Any thoughts? Also I have learned tailstock is low by .003, how much does that affect concentricity?

Cheers,
OldTom

You might blue-up the ways under the tail to see how it contacts.
Consider if you are over-tightening.
With it not tight at all push-pull by hand and see how it stays set or rocks in some manner.
Check to see the indicator rod held in the chuck runs true.
If you OD turn a part held in the chuck and then put your indicator on it the chuck end will run dead true to the centerline of the spindle.

Often there are two offset screws that oppose each other. Does this machine have any adjustment on the front of the tailstock?

michiganbuck said:

You might blue-up the ways under the tail to see how it contacts.
Consider if you are over-tightening.
With it not tight at all push-pull by hand and see how it stays set or rocks in some manner.
Check to see the indicator rod held in the chuck runs true.

Click to expand...

Ding Ding. I always just wrench right down on it. Never thought about it. Went out and worked with it to develop a feel for "just tight enough". After that I set up again with the indicator. Repeatedly less than .001 unlocking the tailstock, moving it, moving it back, locking it, and indicating.

Also took care of what I thought was the tailstock being lower. When I was over tightening before I must have been imparting some serious distortion.

Thank you!

Old tom, - something or nothing

Another thing that can happen is wear / bad seating in the TS body / TS base interface.

Suffering similar symtoms to yours with my SB clone (10'' Boxford) I traced the problem to the interface which on the Box' is clamped down by the TS locking ''bolt''

I overcame my problems by drilling and tapping a couple of locking bolts up through the T/S base in to the body, ..the heads of which when they have to be adjusted (seldom) can be reached with a socket & ext'n up through the bed ways.

In my case firmly clamping the T/S base to the body improved matters no end.

jim rozen said:

Often there are two offset screws that oppose each other. Does this machine have any adjustment on the front of the tailstock?

Click to expand...

No, just a single lead screw. I was surprised myself. I disassembled and cleaned the whole thing to make sure.