Cheap Cast Iron - too cheap to oxy cut?

Tried to cut a bigger hole in the disk of a 35 lb "cast iron" barbell
weight.
No matter how much preheat, acetylene or oxygen I threw at it - it would not
burn. This stuff only blackens and then slumps. Even the trick of
superheating the little slag balls with the preheat and then squeezing
oxygen flow onto them to get them burning and then the underlying metal
going didn't help, the metal only softens but doesn't burn.
The weight is about 1.5" thick, I've cut steel nearly this thick with this
torch. Is this just not using a big enough tip and waiting long enough to
preheat or is this another "mystery metal alloy" effect caused by the
tossing of anything remotely metallic into the mold by the foundry?
Graham
Reply to
Graham Parkinson
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Thats interesting. Does this mean that the carbon in steel is somehow necessary to the burn?
Can you burn wrought iron? There must be something in the structure of the cast iron that prevents burning of the iron or poor heat conduction perhaps? Is it the slag that forms that protects the metal underneath?
Reply to
Graham Parkinson
I'd say it is all about the grain myself. Check out the manuals here - nice pictures and pdf.
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This is the 'English' en version. Go the the main site and pick a language - there are several.
Martin
Graham Park> Thats interesting. Does this mean that the carbon in steel is somehow
Reply to
Martin H. Eastburn
Yes. From what I remember from that part of the class, in order for the oxygen to cut you need the carbon to oxidise. I don't think you can cut stainless steels, either, although I have never worked with ss so, I am not too sure about that.
Reply to
Marc Jones
You cannot flame cut cast iron or stainless steel. The cast iron has too much carbon in it. The stainless form chromium oxide which blocks the cut. A waster plate can be attempted if you are really determined. The idea is that you place a mild steel plate on top and cut through both at the same time. Cutting is still difficult. If you have an arc welder, you might try striking up on the inside of the hole then burn and push the resulting slag down and out of the hole. With a sawing action you could open up the hole. Randy
Reply to
Randy Zimmerman
Cast iron does not cut with a torch. It is relatively easy to drill. A good hole saw would have made short work to enlarge your hole. It would probably need a wood guide clamped to the weight. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net
Reply to
DanG
Well, according to my 1943 edition of "The "Oxy-Acetylene Handbook" cast iron can be cut with an oxy-acetylene torch. Some cast iron is easier to cut than others. In general, it requires much higher preheat, more oxygen pressure, and a different torch technique. Its too much to describe here. If you want to pursue this, I suggest you get a copy of the book.
FWIW IMHO you would be better off pursuing another course if this is a one-off. It all sounds like something one would want to practice before trying to cut something important.
Reply to
Footy
Well the good news is that both can apparently be done but the technique is so deiiferent from the regular carbon steels that a step by step article is required.
If you happen to have this publication "The Oxywelder's Handbook" 15th edition, copyright 1939 by the Linde Air Products Company, New York, NY.
All of Chapter 37 "Special Cutting Techniques" will be very useful. Actually may make a good article for the welding FAQ site, wonder if Linde would mind if we used this information the published?
I have a couple of spare hours this weekend once I finish doing a takeoff for a horse race track grandstand, I think it would be a good idea to duplicate the information in this chapter. Now I just have to find my scanner, still packed away somewhere and the pictures are very handy to understand what they are describing.
Now as far as the format I have PDF, MS Word here and Word Perfect at work or just plain text will be available that is if it is possible to distribute this without ending up in a nice friendly court.
John
Reply to
john noon
Thanks for all the info on cutting cast iron.
Awards for the most definative answers should go to John Noon for his recipes for torch cutting cast iron or stainless and also to Dan for his reccomendation about the hole saw, which I am going to try!
- Graham
Reply to
Graham Parkinson

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