Thanks to all who replied to the original post.

The part is a tool holder for my lathe, hence the need to clamp and
unclamp it repeatedly. There was a lot of milling, drilling and
tapping that went into the pieces before messing them up, so salvaging
them was desirable.

I had access to a college shop during the fall and that's where I did
the milling work. When I saw the way this the first one cut, the shop
teacher said it should still work fine, but I should have trusted my
own instincts and stopped there. Instead, I messed up a bunch of them.
Later, when I slit the first one with a hacksaw, I found that the
..025" slit was not quite enough to tighten it to the tool post.

I made a jig that allowed me to put the part on the lathe and I bored
the rest of them that way and it worked beautifully. Problem is that I
have a bunch that are in need of work. Sounds like the only realistic
approaches are 1) find a way to slit them wider and hope that works,,
2) boring the hole a bit wider and machining a sleeve that can be
permanently installed into the hole, or 3) tossing them.

I've only been hobby machining for a short time and there were a lot
of new things to learn in this project. I've learned a couple more
things just reading the responses to this (e.g. the use of a beer can,
although I never drink the kind of beer that comes in cans).

-Bruno

Bruno wrote:

I was trying to put a 1.125" hole through a piece of steel that's 1.5"
x 2.5" x 1". I was using a mill and the only 1 1/8" cutter that the
shop I was in had. It made a really lousy rough cut that's also about
.012" oversized. This piece needs to be split to clamp down tight on a
1 1/8" post.

Anyone have a suggestion for how to fix it up?

I've never used JB Weld... would it work to line the hole with that
and then bore it to 1 1/8"? I've made a jig so I could put the piece
on the faceplate of the lathe to bore it there; I may not have access
to a mill for quite a while now, so a lathe approach is best.

I was also thinking about a sleeve, but I'm not sure if there is
enough room to bore it out to fit a sleeve in there. If I did, what
size OD on the sleeve would work out? Or should I say, how thin could
the sleeve wall be?

Last resort is to smooth the hole out as well as possible and then
slit it much wider than I had planned, but that's not the best way.

Thanks.
-Bruno