After putting something in the 3 jaw chuck, and nipping up it up, but not really tight, with the dial indicator, keep turning to each to each key hole and tighten slightly. Rotate to next and repeat, and repeat...
The scroll will have some clearance, and very often, you can get it spot on using this method. Give it a try. Works for me.
You can also lap the jaws by putting a piece of mild steel in the tailstock, tightening the three jaw gently at first, add some grinding paste the start the spindle. The diameter in the jaws should the size of job you chuck mostly.
Run for a bit. Stop add more paste, run again. It works really well.
It is very inportant to use MILD STEEL so that the paste embeds itself in the surface.
I have achieved 1 thou at a foot with a chuck in good condition.
