OK, so I found (thanks Jesse) the solder division of Handy& Harmon
and talked to some guy there. They DO make a solder that works at 700
F. which is PERFECT temp. for what I need. The problem is not that
it’s 95% cadmium-which I was told will not release cadmium fumes below
1400 F- but that the 'small ’ unit of flux costs $75 and a minimum lot
(2 0z. ) of solder is about $40. AS IF!!
Plan…D, E?..mix my own darn solder (deja vu anyone?) . This
time I used, by weight, 50% flow 45 (the red colored , cadmium bearing
solder for Gold Filled) and Englehard’s “Silvabrite …appx. 95 % Sb
(Tin) ,4.5% Cu, and .5% Ag. Just cut up little pieces of each and
melted them in a carved out recess in a soft firebrick with a torch
and lots of Staybrite flux. Pounded out the ingot and chopped it up.
This was for a 6” by 4" honeybee wing cut and emboss die, where I
solder a piece of round wire onto the cutting face of the die. Then
when the die is pressed, it’s set on a plate of soft polyethylene
plastic; it cuts the part and embosses the line (where the round wire
is) into the sheet metal part at the same time.
So , I tinned the die with the solder first, then set the wires down
, added lots of Staybrite flux and some more solder and torched it.
This solder mix does not flow , but it can be manipulated into
position well enough for the project at hand with a soldering pick. It
operates up at the heat limit of the flux , as this all took place
mostly obscured by the thick black film of overheated flux…but it
worked!!. I’ve done this several times, but had never actually
accurately measured ingredients. I did not measure temperature, just
went by past experience and feel. 50/50 ended up working within my
desired temp. range. Low enough that Staybrite flux worked , high
enough to incorporate some strength from the 45 braze solder.
This approach relies on using enough solder volume to buttress the
round wire rather than just on the adhesive ability of the solder. The
pressure encountered in forming parts in a press ripps off wires
(too quickly) soldered only with pure soft solder or with only small
amounts of this sort of hybrid solder. Dar www.sheltech.net