At 08:49 PM 5/24/2011, Alistair Bell wrote:
>cut the bolt and drill a new hole...

Better do it carefully.  Counting the depth of the thread you've got
less than 1/32" of meat on either side of a 3/16" hole in a 5/16-18
bolt.  .025 inches actually, assuming National Form threads (good
assumption, I think).

Suggest you a) grind a flat on the side of the bolt and b) use a
smaller hole or better yet c) a larger bolt.  If you have to stick
with 5/16, going to fine thread (24 tpi) will gain you nine thou on
each side of the hole, for a total of .035 or the thickness of nine
Post-It notes on each side instead of six-plus.

Yrs,
d