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Soldering large pieces

More advice during my work on my sculpture if anyone can help I am
working on a sunday deadline and will very much appreciate the help.
I have three copper pieces, etched sheet, that I need to fasten to a
welded frame over a metal framed glass sheet. I am used to working
with silver solder but I know that this is not really the best
application…so I have purchased tin/silver solder to do the job of
attaching the copper placement brackets to the sheet pieces so I can
screw them into the steel frame…But never having worked with this
solder I need advice and direction…or determent if this won’t

I braze heavy sections of steel and copper all the time with
excellent = results. Use Harris 56% silver brazing rod and the
corresponding white = silver brazing flux. For very heavy sections
the Black Flux can be = handy and soaks off in hot water a little
easier. These can be picked up at most welding stores. I would not
use the Tin/solder for this structural purpose. It may be enough but
it is far weaker than a well brazed joint (4500psi per square inch
compared to 25,000 psi). Hope that helps.

Dave Bohm
Bohemian Bicycles

Wouldn’t brazing be the normally preferred method of joining copper
to steel? Also, brazing is good at gap filling, and it’s difficult to
get a really close joint on a large sculpture. Of course, the brass
might show if the joint is visible on the finished piece.

You didn’t say so, but I suspect you are having trouble raising the
temperature of the large copper pieces to the necessary level. A
large oxyacetylene or oxypropane torch should work, or Harbor Freight
has a massive propane torch (actually marketed as a weed burner or
driveway ice melter) for $20 which is great on large pieces.

You might also use firebrick to create a makeshift kiln to help hold
the heat while soldering your piece. (You’re probably already hip to
this if you often work on large pieces).

Richard Bynum
Oakland, CA

Dear Catherine, this sounds like the perfect time to use a cold
joining method like rivets.The steel will require allot of heat even
with low temp solder. Rivets ( simple lengths of copper wire)can be
low temp soldered to the back of the copper sheets then if minimum
force if required to protect the glass they can simply be bent over
after going through a drilled hole in the steel. Hope this helps.
Sam Patania, Tucson