Suggestions from the brilliant minds here? Will that butane
minitorch do the job? Some adaptation for the propane?
The butane mini torches will do small modest jobs in silver, but are
only barely hot enough in my experience. Some are better than others.
The Ronson Multiflame (I think that was the name) that I had years
ago was considerably larger in flame size than, say, the smaller
"Blazer" style ones one sees today, and I've seen even smaller
"pencil" styles ones that are likely good for lighting a fire in the
fireplace or your cigar, but won't solder much more than small wire
work joints. so it depends on just what butane torch you've got. The
fuel itself burns a bit cooler than does propane, but more important
is how much of it the torch is burning at any one time. Many of the
current crop of small hand held butane torches are just a bit to
small to be really useful.
But propane and air does work just fine, though not with the
pinpoint control you may be used to with propane and oxygen. Any
local hardware store will happily sell you a propane plumbers torch
that uses disposable small tanks. These are relatively safe to use
and store, and are hot enough for decent jewelry scale soldering,
though again without quite the pinpoint control you may be used to.
46or silver, though, with it's high heat conductivity meaning you
usually want to heat a wider area anyway, they can do just fine, once
you get used to them. A refinement of this type of torch adds a hose
between the torch handle and the tank, and this may be the better type
for you. Whether you can run this off your existing propane tanks, I
don't know. But I'm pretty certain that there must be some torch type
out there that is designed just for propane and air, and which DOES
hook up to just a propane tank such as you've already got, though I
don't have a brand name right at the tip of my brain to offer you as
I write this.
My personal choice for your situation would be to go with air
acetylene, however, You can get either the somewhat larger B size
tanks, which will last for a very long time, or the smaller R (I
think that's it) sized tanks, and hook this up to a Smiths Handi
heat, a prestolyte, or some similar air acetyelene torch, and you'll
have few limits on what you can do. With larger tips, these can melt
significant amounts ot silver, and with smaller ones, do fine wire
soldering. While acetylene means storing another tank, like Propane,
it's a low pressure tank without the high pressure dangers of an
oxygen tank, and in case of a leak, it dissipates very rapidly,
unlike the much more dangerous (in my opinion, at least) Propane.
And another choice worth considering is a Little torch. While
normally these get used with larger tanks, you can get this with
adapters/regulators that fit the small disposable size propane tanks,
as well as similar sized disposable oxygen tanks. These small tanks
are then pretty safe, simply because the small amount of total gas
they contain. More costly because buying gas in those small
disposable cannisters is hardly economic, but it does give you a
very small, relatively safe package with which you can do occasional
soldering, and if you've a preference for a very small precise torch,
the little torch of course is an obvious preference. At one time I
was doing art fairs and the like, and desired some means of sizing
rings on the spot for customers. That setup worked just fine for me
then without needing a lot of space in the car to transport.
Hope that helps.