On Sun, 22 Jan 2006 12:31:02 +0100, (Nick Müller)
wrote:

Don Foreman wrote:

The key here is gas velocity, set your pressure for whatever torch you
use to provide a low-velocity flame. 4 psi is a pretty good
guideline.

Sorry for dropping in. But this puzzles me a bit.
I mostly have my Oxy-regulater at 2.5 bar (36 psi) and the Ace-regulator
at 0.5bar (7 psi). That is what I have learned and I only change that
setting when I need some wired setting.
The kind of flame I want is regulated at the torch.
If I want a soft flame, I use a big tip and throttle Oxy and Ace down.
If I want a sharp flame, litte tip, oxy fully opened and adjust flame
with ace.

And also, I got better results when aluminium welding with a sharp
flame. That is because I can keep the puddle smaller. Al tends to have a
big (easily huge :-)) puddle because of the good conductivity.

And, while we are at Al welding: Preheat the work. Heat it up until a
wooden stick drawn over the part is dropping little sparks. It then has
the right temperature for OA-welding.

Heating up (to about 100°C) helps getting better first few inches when
MIG-welding Al.


Nick

Whatever works!

I also use the valves on my torch rather than observing any
particular regimen re pressure from the regulator. 2.5 bar of oxy
would be far too high for my torches, YMMV. Truth told, I pay no
attention to the gages at all. I only adjust regulators if I can't
get my torch to work right with the valves. I don't recall the last
time I adjusted the regulators. I know it's best to relax them when
shutting down after use, but I never do it. My bad.

I also sometimes use a wooden splint as a rough temp indicator, but
my usual visual cue is the behaviour of the flux. A useful
substitute for a wooden splint is a soot smear from a raw acetylene
flame. When the soot disappears, you're at about the same temp as the
wood stick test.