How are you measuring the bored hole? I only ask this because I had a bit of fun to start with when measuring a hole and expecting a good fit- to my horror the hole came out larger than I wanted despite me taking much care in boring it. That's when I learned that the dial indicator I used would read three thou small, with the hole therefore being three thou larger than indicated.
I don't know if this is a standard, but this slight overlap of the inside jaws prevents the thing jamming when you try to open it from fully closed. If this small overlap wasn't there, the inside jaws could 'pass' each other, preventing the caliper from opening.
If your final passes are to test fit something, you can take a few passes to remove small amounts of material each time, then test fit. Easy enough. But if the hole has to be a fixed size smaller than the thing that fits it, such as when needing a shrink fit of parts, or a press fit, then you'll have to be able to know exactly how large your bored hole is strictly by measurement. Do some experimenting on scrap to find out this difference in your indicator's reading between inside and outside measurements, and only then can you rely on it to tell you the true diameter of a bored hole.
Just thought I'd bring this up again for those who didn't know, or who have forgotten to factor this in.
[This message has been edited by darryl (edited 06-13-2005).]
I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-