How to re-align tailstock?

[Gary A. Wills]

Hi Rendoman,
Do you have a pair of centers? One for the head stock and one for the tailstock? If you have place a six inch,(150mm), rule between the two with a light pressure. Looking at the rule and how it lies will tell you if alignment is out and in what plane.
Rough set/align and then chuck up a bit of scrap. Center drill the end and turn the outside round for about an inch. Part-off a bit about 1/2" long. file/stone off any pip. place parted off piece back in place where it came from and bring up center in tailstock to hold firm.
Rotate chuck while holding parted off piece staytionary with thumb and forefinger. You will be able to feel any mis-alignment very easily between the two faces,(radial displacement).
Short of having test bars and quality D.T.I.'s this is the easiest method I know. Note most tailstaocks are not true in the verticle plane from the factory.

There is a fairly easy way to align the tailstock , Chuck up a piece of metal larger then the diameter then the tailstock spindle. Turn the stock to the same size as the tailstock . Press tailstock spindle up to the turned metal , using a dial indicator zero out on turned part move carriage to spindle adjust the tailstock to zero and it should be good , top to bottom if out you will need to shim the tailstock.
Works about the best of all ways to realign.

[metric_taper]

As Stilldoinit and Toolmaker posted, LEVEL the lathe first. This is critical. It don't matter how much cast iron is there, the ways will be twisted if not level. If it sat in a twisted state for many years, you may have to give it time to resettle, and keep checking the level until you have it zeroed out. What is the floor it's sitting on, if not poured concrete, you will have problems. Then you can proceed with making sure the lathe spindle is parallel to the ways, then the tailstock quill is aligned with the spindle.
Lots of good techniques here.