I use a cutting torch only rarely. And getting to see someone else
use a torch (and looking over their shoulder) is even rarer for me.

When I try to cut anything more than a thin plate (say over 1/4 inch
thick) the slag flows behind the cutting tip and into the cut. I
spend too much time trying to recut the slag. I have tried different
angles of holding the cutting tip relative to the part to be cut with
no noticeable improvement. Knowing that skilled people can cut thru
plates that are numerous inches thick with the right equipment - I
figure that I should be able to do better also.

If you are inclinded to ask what brand/model/tip size of a torch - I
don't know much more than my primary torch is a Victor and pretty good
sized and my second torch (came with a collection of welding stuff I
bought at auction) is a Meco (also midsized). I am at work and my
workshop is 10 miles from home and I will not be there until Wednesday
evening when I want to cut a plate. FWIW, recently I used the Meco
for the first time and I had the same issue of the slag flowing behind
the tip and into the kerf.

fired this volley in news:722a319c-4cba-4a7b-9984-
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slag flowing behind
the tip and into the kerf.


Increase your O2 pressure, and be sure the tip is very clean and well-
reamed to provide a solid jet of oxygen. The molten metal should be
blown clear of the kerf.

You may also be using too small a tip for the thickness of work. As the
work size increases, the kerf must be wider.

Third, I find that tilting the torch slightly backwards so the jet cuts
further ahead deeper in the work will help clear the kerf. Running dead-
vertical or dragging will tend to blow the melt back into the cut.

Cutting anything thicker than a couple of inches is always tougher than
thin work.

LLoyd

You may also be using too small a tip for the thickness of work. As the
work size increases, the kerf must be wider.

Third, I find that tilting the torch slightly backwards so the jet cuts
further ahead deeper in the work will help clear the kerf. Running dead-
vertical or dragging will tend to blow the melt back into the cut.

Hmm, my experience is just opposite. I usually have a "1" tip in the
torch and have trouble with remelt filling in if I don't change to a
"0" on thin stuff. I often angle in extra on a quick part rather than
make the tip change

Karl

Thanks for the suggestions and insight. I had my O2 at about 20 lbs
so I'll up that a bit. I know that I bought a selection of torch tips
(20+ years ago when I bought the torch set) and I will check what tip
I have been using. I don't think that I am going too slow - I have a
habit of overrunning into cold metal and having to stop to reheat. I
typically have about a 60 to 75 degree angle of torch tip to work so
that the flame is cutting into the work - but that by itself did not
do the trick.

I agree that practice is something that I am lacking. I use the smoke
wrench much more for heating - either heat & beat or to free a rusted
or pressed on part. I don't have a rosebud tip and years ago I even
used the cutting torch (set to a "cool" acetylene rich flame) to heat
the sheetmetal bonnet on my Triumph so that I could hammer form a
power buldge to clear the tripple Webers that I added (that ended up
being a 2 inch deep deformation and the metal is **real** thin (real
tinny when I tap my finernail on it) at the deepest draw).