The only adjustable reamers I've seen have been for hand use, they've
got a square on the driving end. There's a number of different types,
if you've got the common(and cheap) import ones with two threaded
sleeves and a number of moving blades, they need a bunch of tuning
before you can get good work out of them. Typically you'll get 3
blades that cut, maybe one that scrapes a little out and the others
will just be along for the ride. They will tend to chatter when
they're like this, the only solution I've found has been to selectively
stone down the ones that cut until the others also cut. Takes a lot of
patience and you have to get the blades back into the same slots. I've
never used one under power, I'd suspect that the body would tend to
disintegrate on the smaller numbers. I've found that a half-thousandth
is about the max cut I want to make with one, more than that and it
tends to either chatter or bind up. An expansion reamer isn't a
precision tool, but it can improve the surface finish of a hole to a
tolerable degree and will take that last little bit out where you need
a close fit. Don't expect it to improve the accuracy of your hole
location. I like to use them in the lathe after boring a hole, locking
the headstock and using a T-handled tap wrench between the hole and the
talestock with a center in it.

Stan