As a further contribution to this thread, there are many applications coming on line in the shipbuilding,automotive and aircraft
industry in the metal to metal bonding area. These epoxies are not available to the general public. An example is the chassis of
the Lotus Elise. It is fully bonded aluminum without welds. In the ship building industry, the major detractor to adhesive use is
not structural. It is insurance and IMO regulation issues relating to heat vulnerabilities during fires.
Steve

"Existential Angst" wrote in message ...
Awl --

First, is "two-part epoxy" redundant? Does "epoxy" nec. imply two parts?

Next, does the strength of a two-part epoxy vary with its setting time? Intuitively, I would think the longer the stronger.

The classic is "5-minute epoxy", but I believe I have seen 60 sec epoxy, and I have 90 minute epoxy.
I find 15 minutes to allow for a few parts without rushing, and without waiting forever to cure. Altho I have also found that
the epoxy is not really hard in that time.

The stuff I have now is Permatex (a 30 min epoxy), but DevCon and Loctite are big players, with big-time industrial uses, such
as epoxying bearings, instead of press-fitting them into their housings. I believe DevCon stated that epoxying bearings is in
fact the preferred method, being stronger than press fit.

The shear strengths are enormous, but require at least .010 on the radius for good bonding. So a slip-fit for epoxy would be
counterproductive.

In some of my proposed assembly methods, I could use set screws, pins, epoxied pins, or just epoxy -- typically nominal 7/8 alum
round in 16 ga SS tubing, or some such.

I thought epoxying would be slam dunk, and indeed it saves machining, but goddamm, you gotta pick yer poison, it seems. I could
see arguments for actually using a mechanical method AND epoxy, in some applications.

A feature of epoxy, which could be both good and bad, is its instability to heat. I think boiling water, or at least not that
much hotter, can undo epoxied parts.

Iny thoughts?
--
EA