How to Fix Headstock/Tailstock alignment?

[goldendj]

I have a JWL-1236, bought 20+ years ago wheny wife indicated it might be a woodworking activity we could enjoy together. Got it assembled & then she got really sick with our first (of three). ICU-level sick with all three, and then raising them, military moves, family ... Finally started using it a few years ago, mostly pen turning. I've noticed the holes, and turned blanks, don't seem to be quite round. It looks like the headstock is slightly lower than the tailstock, which I don't know how to fix. Doesn't seem to be anywhere I could shim it up.




The tailstock also seems to point off-axis towards the back.


I picked up a double-headed MT2 thing to check alignment, and it's definitely off. The tailstock only accepts a short section before binding

No clue what to do. Any suggestions?

 

[monophoto]

Not an uncommon problem.

The first thing to do is check alignment with the tailstock ram extended as far as it goes. The reason for that is that misalignment will be amplified as the ram is extended, and tuning up the lathe with the worst-case extension will mean better alignment at all extensions.

Also, separately check both horizontal (front to back) alignment and vertical alignment (top to bottom). Front to back is easy to correct - the JWL1236 appears to have a rotating headstock, but the exploded parts diagram shows a ring with detents that fix the positions where it can be locked down. If you can't just realign the headstock in the horizontal plane and lock it down, then you need to look for some screws that can be loosened that allow you to tweak the horizontal alignment of the detents.

But you should also check the tailstock for horizontal 'wobble'. Wobble comes about when the protrusion on the bottom of the tailstock casting is microscopically more narrow than the spacing between the bedways, and a very slight deviation in those dimensions can allow the tailstock to rotate very slightly - just enough to throw off the alignment. If that is the case, there's not much that you can do other than to learn to compensate.

Misalignment in the vertical plane is harder to correct. Your photos suggest that the headstock is slightly lower than the tailstock, and in that case, it may be possible to add some shims under the plate that the headstock rotates on. It probably won't take much, and it would probably be wise to undercompensate with shims, and then just learn to deal with the residual error.

Final point - its a wood lathe, so its not going to be as precise as a metal lathe. I suspect that most wood lathes have some misalignment that users have to learn to work around.

 

[jttheclockman]

Louie gave good advice but let me add one thing before you dive into all that. Make sure the lathe is level all ways around and the table it is sitting on is. Could make a difference because they do get racked. Good luck.

 

[goldendj]

Thanks, monophoto and JT! I already checked the lathe bed lengthwise and crosswise to make sure it's level and untwisted, to within <0.1 deg each way. I also used a dial indicator to check headstock runout at <0.001" +/-.

I pulled off the headstock completely to see if there was a convenient place to shim it up but didn't really see anything. It's just a solid casting that rests on a cast dovetail ring with two dovetail bars to hold.it down. I suppose, since I have almost never rotated the headstock, I could just place some shim material around the ring and redo it if I ever move it.

The tailstock definitely rotates slightly when I lock it down. I've tried pushing it CCW when I lock it down, but there's still a bit of misalignment.

I'm not expecting machine shop tolerances but I would like to be able to drill and turn without noticeable out of round ...

Will try shimming the headstock when I get home
Would it help to try shimming the sides of the tailstock guide, or will that just come off each time I move it?

 

[smik]

On a 1014 lathe I used a penny wrapper under right side of tailstock. Brought it right in.

 

[jrista]

Louie gave good advice but let me add one thing before you dive into all that. Make sure the lathe is level all ways around and the table it is sitting on is. Could make a difference because they do get racked. Good luck.

This is an important one that John recommended to me when I asked some time ago. It was part of my alignment issues, and definitely helped when I fixed this.

 

[jttheclockman]

Another tip that has helped people through the years and that has to that tailstock nut and how it positions the tailstock everytime you lock it down.

https://www.penturners.org/threads/tail-stock-slipping-back.162502/#post-2051435