"Steve Smith" wrote in message
...
| Your holes should be nice snug fit to the bolts. I'd suggest maybe some
| reading about shear strength would be a good idea. Getting a value from
| someone else doesn't provide nearly the understanding that figuring it
| out yourself does. Same applies to the frame.
|
| Just my thoughts,
| Steve

Great point. I will also add that the place most bolts fail in tension
is where the shank meets the threads. High stress there, and bolts in shear
will fail at that spot or under the bolt head, where the bending forces are
at the worst, thus leading to the explosive failure noted. Best bolt
practice says no threads in bearing, which means the bolt has to just the
right length. SAE bolts have lots of threads, which means you usually have
a lot hanging out, but that very requirement is why most aviation fasteners
have so little thread. The tighter the hole the better as well.
Interference fit is actually the very best, but harder to actually do in
practice.
A way to make up for it is to use a hollow spacer whose length is just
the smallest amount shorter than the length of the bolted joint. The spacer
takes up the load and the bolt merely holds it all together. Needless to
say the spacer shouldn't be soft seamed pipe, but then again a larger
fastener equivalent is better than a smaller one, providing you have
sufficient hole edge margin. Again, the snug fit is better.

There's a web site out there called bolt science.... I think. Hang
on... here it is: http://www.boltscience.com/ This is the good stuff!