Did you take apart the chuck? On a 3 jaw chuck, the jaws NEED to be in proper order. Or it will not hold parts on center.
Yep I did, however I had no clue that they need to be in the right order! I only remember myself wondering how they all end up in the right position in the end... I'm quite happy I didn't quite manage to describe my issue properly, I'm learning way more like this!
If the test rod starts true, then progressively becomes more eccentric as it furthers the headstock (cone shaped pattern), the chuck or spindle is wonked. If the test rod orbits in a cylindrical pattern, the jaws are not installed in the correct order, as Chips and More explains above.
It sadly does get more eccentric as it furthers the headstock, both with the 3jaw-chuck and with the collet chuck.
Your last description was pretty good.
Does the collet fit into the bore, or does it fit into a collet chuck that threads on the spindle.
I am thinking the spindle face has a ding in it or something causing the chuck to mount cock-eyed.
It's a collet chuck, screws on the same thread as the 3jaw. So I kinda guess the only thing that's left is, as you say the spindle face or the thread. I can't quite see the thread causing it though!?
Post a picture of the lathe and chuck. that might help .
I thought I'd best do that anyways when I'm with it tomorrow (it's by my grandmother). You might all just spot many more things that aren't quite right.
Thanks a lot everyone, it's very seldom that you get this much help!