does the original hole really have such a thin wall thickness at
tangent? (rhetorical question)

should see if you can use a 3/8" bolt, enlarge the other holes.

alistair

On 24-May-11, at 6:33 PM, David Beierl wrote:

> 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