Thanks, Charles
you could use a hard silver solder
Well, thing is, that I want to use a gold solder. I am looking for a
golden seam in an otherwise steelish blue ring.
But maybe I can have anything I want 
Oh, well…
One thing I remember from high school machine shop is being told
that the cutting tips on metal lathe tools are often soldered to the
tool shaft with hard silver solder. That amounted to license to
proceed in whatever ways I found necessary, where welding, braze
welding with bronze rod, or using low-temp soft solders were not
good options. No big deal ; I never ran into steel soldering problems
I couldn’t solve.
FFW to the other day, assembling the teensy tiny little pieces of a
peace sign pancake die, 3/4" diameter, with holes. The Dreaded 3/4"
Peace Sign… the remake;
the unspeakable horror , come to haunt me again. Doing this design
as a pancake die presents a dozen serious challenges, which are only
slightly less challenging after years of pancake die making. Someday
I will write it all down, but will keep the gory details to myself
for now, for lack of time. One of the very difficult things about
the job is soldering the parts that cut the holes to the plate that
acts as their hinge. The fact that it’s a steel soldering job is not
the difficult part, compared to positioning the parts, but it is what
I want to share a little tidbit about just now.
Important Thing Number One about silver soldering steel is that the
parts are clean and oxidation free. This is not easy after heat
treating the steel parts, since wrapping the parts in stainless foil
is not something I take the time to do on pancake dies, because it
interferes with their handling, and proper cooling, and would slow
me down too much. I do have to clean out the drill holes that are for
alignment pins, in the itty bitty peace sign hole parts, and I can
file the front and back surfaces of them, but the sides remain
oxidized. Even though no solder is required to adhere to these
sides, there’s a chance the oxides could detach and contaminate the
flow in critical areas, so I tried something a little different this
time.
I wanted to use hard solder this time, for strength, over the easy
I’d used before, and which had come undone. I wanted the joints to
be really clean, so what I did was get a good thick layer of white
paste flux on there and keep it molten long enough for it to clean
off the sides of the parts. I kept it just at the transparent liquid
phase, and in a couple minutes the sides of the parts turned from
dark, dark gray, to the nice, light gray of clean steel. The molten
flux cooked off and dissolved the oxides. The added few hundred
degrees needed for hard solder quickly reoxidized the steel and the
flux became a black soup as the solder hit that maximum fluidity
stage, but the flux had done it’s job, thank you very much.
Dar Shelton
Dar,
Why not skip the hardening step if you are going to solder on the
die. Any hardness you put into the steel by heat treating is lost
when you raise it to silver soldering temperatures.
James Binnion
James Binnion Metal Arts
Hi Dar.
Try the black brazing flux. Available at welding supply houses. Made
by Harris, just like the white paste flux, except it’s pitch black,
and works better on steel. Looks nasty, works great. (for steel)
Regards,
Brian Meek
Dar - What are you soldering on steel with ? if its tin based lead
you need the pink fluid from the stained glass supply more commonly
known as ruby fluid and a 50-50 tin lead solder (from stained glass
supply )this works really well ( 60-40 doesnt work on steel too much
tin ). All early motorcycle gas tanks Indians, harleys were stamped
steel sheet lead soldered at the seams. You will need a wire brush
and torch and soft natural bristle brush don’t overheat the steel
there is a bit of technique involved much like tinning copper
cookware. if using silver on steel there should be no trouble using
the standard paste flux used for soldering silver jewelry products
goo
That’s not necessarily true, even though it’s something we’ve all
heard since we were little and is accepted wisdom, and it’s
persumably true to whatever degree it is, when talking about tools
that are harder than the pancake dies I make. Experience with the
exact conditions I’m describing shows a bit of a different reality.
Tempering takes a couple of minutes to have a lot of effect
(according to a metallugy book I have, most tempering takes place in
the first few minutes, so we can assume it doesn’t happen in
seconds), and if soldering is done quickly the steel retains some
hardness.
Also, I doubt that heat treating after soldering is a good idea, so
I’m not going to try it. I know how soft the 0-1 is without heat
treating and it’s not an acceptable degree of toughness to charge
people money for, for dies that are supposed to last. I’ve soldered
a lot of donut die parts that were already heat treated , and
especially if a lower temp silver solder is used, the steel will
retain a significant amount of hardness. Just take my word for it,
even after soldering, the steel is still significantly tougher than
with no heat treating.
Pancake dies shouldn’t be hardened very hard to begin with, if you
want long life without breakage. Even though I don’t harden them
very hard, I still see more breakage than deformation of cutting
edges due to steel softness. Another thing to consider is that the
suggested method of annealing hardened 0-1 is to take it up to the
quenching temp, and then slowly reduce the temp over the course of
several hours, like a day. That’s what it takes to remove all the
hardness
Dar
Yes I’ve tried the black flux. I like white because it’s easier to
see what’s going on and if used right, works great.
DS