"Michael Koblic" wrote in message
...

"Ed Huntress" wrote in message
...


[...]

I forgot one important thing: If you want to try epoxy, keep in mind that
its maximum strength, particularly in metal-to-metal bonding, is achieved
with a bond layer approximately 0.002" thick. Any thinner, and the
strength goes to pot -- especially peel/cleavage strength. I often leave
a little sanding grit in the joint to be sure I'm not starving it out.

It can tolerate a thicker layer, up to around 0.006" or so, without
losing a lot of strength.


Thank you and all the others.

I was not aware of copper being a problem with glues.

I have your "scratch-in" method saved in my works folder from last time
you mentioned it here and was going to try it next. The only reason I was
hesitating is that the reverse side of the brass foil is supposed to look
intact and in the past any speck of dust or other mechanical disturbance
produced blemishes which were impossible to get rid of. However, I guess
now is the time to try again, very carefully.

I'd try the Scotchbrite, on a flat piece of glass or something similar.


As for the optimum layer of glue I wonder if going to a coarser abrasive
would help by producing more pronounced peaks and valleys on both sides of
the material - perhaps just on the steel side.

It sounds like a reasonable idea. I've experimented a bit with grades of
sandpaper, however, and I prefer using finer grits. But you may be on to
something there.


I was going to try the solder paste method as a last resort. I have played
with a couple of different kinds and I don't like them for ordinary
soldering/silver soldering. However, this may be the right place for it.

--
Michael Koblic,
Campbell River, BC

Good luck. Let us know how it works out.

When you're bonding metal with strong adhesives, it's good to keep the
peel-strength/cleavage-strength issue in mind. That's one weakness of those
adhesives in metalwork. As an aside, this is what rivet-bonding is all about
in making aircraft wings. If you look at how the rivets are placed it's
clear that they're not being used for the sake of their shear strength, as
aircraft rivets normally are. They're there solely to keep the edges of the
wing skins from lifting and starting a peel failure.

--
Ed Huntress