On 15/06/2019 12:11, Chris Green wrote:
I know this is a bit of a 'how long is a piece of string' question but
I need some sort of way of working out what gas brazing torch I need
to do something.

I want to fix a small crack in a transaxle casing from a mower, the
casing is maybe 8" in diameter and made of 1/8" thick (or a little
thicker) aluminium.

I have a "laser 4707" aluminium brazing kit and my trial on a bit of
1/8" thick aluminium angle worked pretty well (I'm used to soldering
and welding so something sort of half-way wasn't too difficult). I
did that with a Bernzomatic TS2000 torch which I bought a long while
ago for odd plumbing jobs.

However the Bernzomatic TS2000 won't get the transaxle casing hot
enough, it's fairly close but not enough to get the material to 'tin'
nicely.

So, would a bigger/better torch which uses the same gas canisters as
the TS2000 be enough. The Bernzomatic site seems to suggest that the
TS4000 (which Screwfix sell -
https://www.screwfix.com/p/bernzomat...ng-torch/71976)
is quite a lot beefier than the TS2000 and it can use the MAPP gas
bottles which are also hotter I believe.

Still looks a bit small to me, although I agree that MAPP will give you
some more "oomph".

My "big" propane torch has a nozzle about an inch in diameter and I
suspect that this might struggle with your transaxle. I'm making the
assumption here that aluminium casting alloys "suck" heat away faster
than iron or steel.

My other "secret weapon" for brazing ferrous or cuprous bits is a
selection of vermiculite "fire bricks" as sold for solid fuel stoves,
with these you can build some containment and reflection for many shapes
(although a transaxle is probably quite difficult).

I do have the cheap Lidl inverter welder, if I had your problem I might
be tempted to get a TIG torch for it.