This may not matter much, but strength and stiffness are not necessarily proportional. Epoxy stiffness (not necessarily industrial strength epoxy):
https://netcomposites.com/guide-tools/guide/resin-systems/strength-stiffness/

Stiffness of epoxy from chart is 3.5gpa which is ~508ksi, compared To 10700ksi for aluminum or ~30000ksi for steel.

Therefore, regardless of strength, a layer of epoxy will be 21 times more flexible than an equivalent layer of aluminum and 59 times more flexible than steel. Given a thin enough layer of epoxy, this may not have a significant impact on rail mounting. But, a 500lbf bolt preload over a 1in^2 of .25" thick epoxy will cause ~.0002" of deflection in the epoxy layer.

Quote Originally Posted by hanermo View Post
I disagree.
So do all major industrial manufacturers of specialist epoxies.
Hysol (locktite) 3478 is one example.

Rated strength in crush is 1000 kg / cm2.
So my 2200 mm long rails, 2 of, 35 mm wide, have a 3.5 x 220 x 2 x 1000 = 770.000 kg crush rating. Each.
== 1.5 Million kg.