oxy cutting without acetylene

hi all, i remember some years ago a person i worked with telling me that once the cut is started you need only oxy to maintain it and can turn off the fuel. Ive been experimenting with this a bit at work lately as we have a bit of spare time. I've had mixed results.

The plate im working with varies from about 1/2" to 2". Im using an electric style plate cutting machine. There are all the usual adjustments for height, travel speed, etc. I start the cut as usual with a suitable tip and neutral flame, then once the cut is proceeding well i start to reduce the acetylene. Ive had some excellent results by reducing the acetylene to an extreme oxidising flame, to the point where the flame almost goes out. i reduce the travel speed a little at this point. The cuts im obtaining are really great - almost laser like. They are dead clean, with no slag at all and a very neat edge that doesnt need grinding. As a side benefit, there is less heat distortion on the cut, on full plate length cuts you can notice that the cut off section moves away from the main section by very little. It is noticeably cooler, to the point that you can handle it without gloves within 10 minutes. using less acetylene is only a minor benefit to me.

I cant completely turn off the fuel though, or the cut wont sustain itself very long, maybe a couple of inches. does anyone have experience with this type of cutting? Is it common? can anyone give some general rules to follow or possible hints, is it possible to cut without any flame at all once the cut has been started? As a general rule, would you keep the same oxy pressure as for a flame cut? should travel speeds be about the same?

Any hints or book reccomendations would be appreciated!

Reply to
Shaun Van Poecke
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For burning you might find maap to be a better choice.

Reply to
beecrofter

Don't know of a book; but you can cut carbon steel with practically any oxy-FUEL flame.

Places I have worked in / for have used propane and / or natural gas as the fuel for cutting. I have also heard that you can get equipment that uses gasoline for the fuel.

Wolfgang

Reply to
wfhabicher

The first time I have seen this done was with REAL heavy stuff. The guy was burning a 4" diameter shaft out of a 4 foot diameter wheel. They preheated with a big rosebud (maybe 2), then applied an "Oxygen Lance" which was a piece of 3/8" water pipe, fed right from a pair of oxygen cylinders running at 120 psi. With a hole that big in the pipe, you can guess how long those cylinders lasted! Sparks and slag shot out about 20 feet. Real spectacular at night. This, of course is not quite what you are doing, since the heat is contained pretty well inside the hub of the wheel. We use a small oxygen lance to clean out a plugged tap hole when pouring cast iron or making blooms. But in these cases, the cupola provides plenty of red to white hot iron to make the oxygen happy.

Pete Stanaitis

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Shaun Van Poecke wrote:

Reply to
spaco

"Shaun Van Poecke" wrote: (clip) The cuts im obtaining are really great - almost laser like. They are dead clean, with no slag at all and a very neat edge that doesnt need grinding. As a side benefit, there is less heat distortion on the cut, on full plate length cuts you can notice that the cut off section moves away from the main section by very little. It is noticeably cooler, to the point that you can handle it without gloves within 10 minutes. (clip) ^^^^^^^^^^^^^^^^^^^^ The characteristic described here are definitely NOT obtained with an oxygen lance. I believe Shaun is onto something that the rest of us could benefit from, if we would pay attention to what he is saying.

Reply to
Leo Lichtman

the book on the subject.@!

Reply to
Jerry Wass

hey, you overestimate the value of what im saying ;-)

Im just trying to lift my game when it comes to cutting. call me lazy if you like, but i dont like grinding that much, and we do a lot of plate cutting in our shop, most of it heavy. It can be frustrating for me sometimes, because ive seen some really excellent cutting in my time, and i know there is something i could be doing better to get results like that but cant quite put my finger on it.

Shaun

Reply to
Shaun Van Poecke

Reply to
woodworker88

The instructor in my machinist course (circa 1978) Told us "When a particularly difficult job comes in, the smart foreman gives it to the lazyist guy in the shop, cause he'll figure out the easiest way to do it".

Words to live by?

Mickey

Reply to
Mickey Feldman

Only if he is lazy like a fox.

Wes S

Reply to
clutch

Shaun,

From what I understand, there should be little difference in shutting off the acetylene during a cut. The heat is generated from the O2 burning the iron which allows the cut to continue. I can't say as I've actually tried it, but I know it does work. I see no reason why there would be less slag though.

Wayne Sippola

Reply to
Wayne S

Oh crap, now ill have to try to be less lazy at work so i dont get given too many jobs. thanks a lot Mickey!

Shaun

Reply to
Shaun Van Poecke

I had another 10 hour day of plate cutting today.... I am getting very neat consistent cuts that are clean. im settting neutral, then once the cut is esteblished, i turn down the acetylene as low as it will go without actually going out. It really does reduce slag, im guessing that less heat means the slag has less chance to rejoin the original material. there is the very slightest slag on the bottom of the cut, but it doesnt need grinding. a quick scrape with a paint scraper and it all pings off. the cut is very square and sharp at the top edge, and the face of the cut shows a much cleaner, lighter shade of grey than a regular cut. This is the way im going to be cutting from now on.

Shaun

Reply to
Shaun Van Poecke

we have a couple of plasmas at work, and most places ive worked at had them. we also each have our own oxy setup with our own torches and tips and a few spare oxy setups for plate work. my take on the two is that if you have a low level operator on an oxy and one on a plasma, then the plasma will come out ahead. if you have an expert operator on both machines though, the oxy is better in my opinion. The oxy gets better and better as the plate thickness increases, especially for things over 1". I've never used a plasma that could cut 3" though i think they do make them. the main problem i find with plasmas is if they dont have a perfectly clean and dry source of air, and also that the arc is rarely dead straight. it usually leans off to one side.

for stainless and copper and aluminum cutting, the plasma is of course the only option. for sheetmetal its also better. lasers on the other hand are another topic entirely ;-)

Shaun

Reply to
Shaun Van Poecke

Sounds reasonable. I've had lots of problems with the plasma cut ending up much wider at the bottom than at the top, even noticible in

1/2" plate. ww88
Reply to
woodworker88

. I see no reason why there would be less

Possibly because the oxygen combines with only steel, not acetylene? Does a better job of burning the steel.

Harold

Reply to
Harold and Susan Vordos

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