"Ed Huntress" wrote
On Mon, 14 May 2012 22:28:13 -0400, "Existential Angst"
wrote:

Iffin you REALLY wanted to be sure that a nut won't fall off a
screw, or a
screw will loosen, wouldn't plain ole 2-part epoxy be the best bet?

There are epoxy thread-lockers made for volume production. They're
hollow phenolic beads, half of them filled with resin and half of
them
with hardener. The threads are dipped in a weak adhesive and then in
the beads, whereupon they can be stored for as long as you want.
When
you tighten the nut the beads crush, the epoxy and hardener mix, and
the mess hardens.

For non-production use, Loctite is much more convenient.


Also, if an epoxied screw/nut did have to come off, wouldn't a
little heat
do it?

A fair amount of heat. And the epoxy doesn't melt. It may get soft,
but it chars.

Five-minute epoxies can handle less heat than the slow-cure types.


What Ed wrote, but also..

Split Lock washers DO NOT work and should not be used. Steve W.'s link
http://www.boltscience.com/index.htm has a graph showing that they
fail quicker under vibration than a straight bolted conection.
Basicaly when fully compressed they act as a flat washer giving two
surfaces that can slip. Once slightly released, they activly permote
the rotation of the bolt or nut.

Star washers I think work as long as the conection is tight enough to
actualy cut into the two surfaces.

Look at how cars are put together now. IIRC for critical areas they
use belvel washers with embosed squares or stars that alow for higher
clamping force upon compression.

--
Stephen B.