"Terry Coombs" wrote in message
...

"Cydrome Leader" wrote in message
...
I finally dug out the $2 garage sale Craftsman (really Harris)
oxy-acetylene cutting torch. It came with a cutting head of unknown
size
which I just cleaned out and #7 torch tip.

It passes the soapy leak test when pressurized, and the o-rings
appear ok.

I've not used one of these before but have run into a problem.

I set the acetylene until the flame is not a smoky mess. Then I add
oxygen
at the cutting attachment valve (It's wide open on the torch
handle) then
I push the cutting lever and the flame gets really vicious. When
let go of
the cutting lever, the thing goes BANG and the flame goes out.

What might be going on here? I've got a new set of torch side
flashback
preventers to attach before I play with this more.

The welding forums go on about how this is backfire vs. backflash
and that
the torch is leaking air or the O2 pressure is too low or something
is
broken. It's all vague.

I had the O2 as about 10PSI at the regulator and the acetylene
around 5.
Not sure if these are correct-ish.

Suggestions?


Acet around 5 is OK , bump that O2 pressure to more like 20-25 and
try again . The preheat flame should not change when you depress to
oxy feed to start a cut . To set acet pressure open the torch valve
all the way , increase pressure until the flame starts to pull away
from the head then back off until it comes back . Should be no
smoke/soot from it if properly adjusted . Oxy pressure is going to
vary with the tip size and thickness cut , but 20-25 is a good place
to start .
--
Snag
I got this info from somewhere on the net , probably either here or
SEJW , and while I don't recall the author I did respect his opinion
.

Since s.e.j.w hasn't helped I'll repost this he

I bought an old Victor portable welding kit with a J28 torch, 2-W-J
welding tip and Uniweld 17-15 rosebud, which apparently consume
acetylene much too fast for the MC tank in the carrier. According to
Victor only a size 000 tip is within spec, but which size tip do
people really use for light welding like thermocouples and auto body
rust repair?

http://victortechnologies.com/IM_Upl...B)_Jul2011.pdf

jsw