Help, lathe doesn't run true

[Chris Yarish]

For general purposes, my lathe performs nicely.
For smaller detail work, like pens, I don't think it runs as true as I once thought.

My pen mandrels have a wobble, more obvious as you near the tailstock, and my finished pens have a slightly elliptical shape, only being out 1/32 or less. Upon inspection, my tailstock center sits just a hair below my headstock center. The head and tail centers both run parallel to one another and parallel to the lathe bed, so the "out" is on the vertical axis relative to the bed.

My question is...can I shim my tailstock with some card-stock, paper, or other material, or is there a more "professional" method to correcting this...or is my lathe just going to be out indefinately?

Any advice would be appreciated.

[Steve Mellott]

Chris:

I purchased a Jet 1642 lathe about 6 months ago and had the same problem. I tried the following solutions:

1. Cleaned all the packing grease from the ways and the underside of the headstock and tailstock.
2. Replaced the tail stock center with another to ensure that it was not defective.
3. Checked the tail stock center rotation in the tail stock to ensure that it was turning in a true manner.
4. Individually adjusted each foot leveler to see if that would fix the problem.
5. Put the headstock and tailstock at each end of the lathe and lifted the lathe in the center.

Unfortunately, none of these solutions solved my problem, although they have helped others. You may want to try them with your lathe. After I explained the problem to Jet, they sent me a new tailstock and that solved my problem.

Steve

[David Walser]

Chris,

Are you sure your lathe is out of alignment as opposed to your pen mandrel being bowed or bent? If you put too much pressure on the mandrel with your tailstock, the shaft will bow -- giving you the result that you're seeing. Sometimes the mandrel's shaft will spring back after you release the pressure, making it appear that the mandrel's straight when you examine it.

If a bent or bowed mandrel is not your problem, yes you can shim your tailstock. However, if your lathe used to be in alignment, there's very little you could do that would make it go out of alignment. So, make sure you've checked all the standard things -- like making sure your lathe is level (so your way's aren't twisted) before you start shimming.

Good luck!

[Gordon Seto]

Or does your lathe has a swivel headstock?

[Keith Christopher]

For general purposes, my lathe performs nicely.
For smaller detail work, like pens, I don't think it runs as true as I once thought.

My pen mandrels have a wobble, more obvious as you near the tailstock, and my finished pens have a slightly elliptical shape, only being out 1/32 or less. Upon inspection, my tailstock center sits just a hair below my headstock center. The head and tail centers both run parallel to one another and parallel to the lathe bed, so the "out" is on the vertical axis relative to the bed.

My question is...can I shim my tailstock with some card-stock, paper, or other material, or is there a more "professional" method to correcting this...or is my lathe just going to be out indefinately?

Any advice would be appreciated.

I know this is going to sound obivious, but are you sure your tailstock is always 'seated' completely in the end of the mandrel ? I had a problem with my Rikon tail stock coming loose slightly and the resulting problem was wobble along the mandrel. Make sure the point of the tailstock is fully seated (not tight) but fully seated.

[Vern Little]

I purchased a mandrel from Woodcraft where the centering indent in the end was off center. It took a while to figure out why my pens were not round.

[Chris Yarish]

When I bring the tailstock to the headstock, they align on the plane parallel to the lathe bed.....but the tail stock is just a hair lower than the headstock. To me, this rules out any problems with the seating of the mandrels or the trueness of the mandrels but, nevertheless, the mandrels I have are all new (I have 3), and I seat the tail center on the inverted cone in the mandrel first...then I push it gently toward the headstock.

So....again...is shimming it a good idea, or is this a hack fix?

If it's a hack fix, I'd entertain purchasing a mini dedicated for pens.

[Scott Conners]

You should be able to get some brass shim stock at the hardware store. I'm not sure about how to attach it, and it'll wear down as the headstock slides, but it'd be better and more permanent than cardstock or similar. You can also turn pens without a mandrel, just using the bushings on either side and turning between centers. If your mandrel is part of the problem this might help.