Just got a Phase II tool post piston type. I like it a lot but I see
the difference with it's repeatability. You have to hold the tool
holder in position the same each time to be as close as you can be
before you tighten it. Not bad though but the next one for my other
lathe will be a wedge. Anyway, it has a threaded hole in one side of
it. This may be a dumb question but, what is it for?