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Thread: Oxy Acetylene torch cutting cast iron?

  1. #1
    John Madarasz's Avatar
    John Madarasz is offline Stainless
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    Default Oxy Acetylene torch cutting cast iron?

    Considering trying to cut through some 3/4" cast iron on a repair I'm doing...I'll need to cut through not only the 3/4" cast iron, but also some nickel rod repair in the same area. I have a tip for my torch that's rated for 1"...should I even bother trying, or look at another avenue for repair, refab of part.

    I can post pictures if needed, but really just want to know if it's possible to cut cast iron and built up weld. This is s structural repair...a broken foot pedal arm on an old heavy duty hollow chisel morticing machine that gets a lot of use fwiw

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    J.R. Williams is offline Hot Rolled
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    Default Cast Iron

    John
    My vote is to use your angle grinder to do the cutting. The area is now ready for welding or brazing.

    JRW
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    Mud's Avatar
    Mud
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    You can heat it red hot and blow blobs out a little at a time, but it doesn't cut like steel. It's a mess.
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    USMCPOP is offline Titanium
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    Mike C. is offline Diamond
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    I'm for the grinder, too. Not only will you make a mess, you are going to cause the repair area to be all screwed up and almost ensure a failure. Grind it (even better, file it to finish), reinforce the joint with a couple of plates and screws, and then braze it.

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    gbent's Avatar
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    That is what arc-air torches are for. Plasma too, if its a big-un. This is one time your oa torch is useless.
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  7. #7
    Richard Rogers is offline Titanium
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    If you cut that much cast iron with an angle grinder, wear some sort of dust mask. Cast iron dust can really make one sick if much of it gets inhaled.

    Post #6 is pretty much right. A plasma with sufficient capacity would be wonderful for this job.

    Richard

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    John Madarasz's Avatar
    John Madarasz is offline Stainless
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    Thumbs up Thanks for the info

    Thxs to all for the good info... a big help. I didn't even try to O/A flame cut based on the excellent replies here, instead cut out my pocket on the band saw, then drilled across the cuts in a line and broke the cast out, quick cleanup on the Bport and ready to fit in new part. A quick, easy and efficient job...

    Thxs agn everyone, and Best Wishes for a Happy, Healthy and successful New Year!


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    sandman2234 is offline Titanium
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    Air arc's are great when it come to cutting stainless also. Using one is like lighting a bunch of fireworks in your hand and waving them around. You also aren't likely to run one off a Tombstone buzzbox, as they do require a generous amount of power and air, but you can run them all day without having to change out bottles.
    David from jax

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    altered is offline Aluminum
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    Arc-Air should be avoided on cast iron because the air jet make the cast iron to harden. There is cut rods from different manufacturer that does a great job really fast. You can gouge and cut and it's relativly clean. Plasma is good too the air that flush the material is hotter than the arc-air....

  11. #11
    S_W_Bausch is offline Diamond
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    This thread is years old, but I can add this:

    Handbook-Manual Cutting

    Where it is said:
    Cutting Cast Iron Oxygen cutting of cast iron is difficult, but it can be done if you know how. It’s the graphite in cast iron which causes the trouble; although a form of carbon, normally thought of as combustible, graphite simply won’t burn; it must literally be washed away. To cut cast iron is slow work, and requires a special technique and plenty of patience. To cut cast iron, use a nozzle of the size you would use for cutting steel of the same thickness. Select a nozzle with maximum preheat capacity; a nozzle designed for minimum acetylene consumption simply won’t do the job. Adjust the preheat flames, with the cutting oxygen flame open, so that they have a decided excess of acetylene (the excess acetylene ”feather” should have a length at least twice the length of the inner cone). Make the flames as strong as possible. Then preheat the edge to be cut, all the way from top to bottom. The more you preheat, the easier it will be to get the cut started. Once you have done this, concentrate the preheat flames at a spot on the top surface and heat a circle at least 8 mm in diameter until the metal is actually molten. Open the cutting oxygen valve for an instant, just to blow the slag off the surface of the puddle. Then turn your torch so the nozzle is pointed 45 deg. away from the direction of the cut line, open the cutting oxygen valve wide, and start to move the nozzle back and forth in a progressive series of short arcs which intersect the cut line.
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  12. #12
    jimcolt is offline Cast Iron
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    I would use my plasma.....it will cut it like it was carbon steel. The nickel won't even be noticed. If you do not have access to plasma ten a cutoff when on an angle grinder should do the trick.

    Jim Colt Hypertherm


    Quote Originally Posted by John Madarasz View Post
    Considering trying to cut through some 3/4" cast iron on a repair I'm doing...I'll need to cut through not only the 3/4" cast iron, but also some nickel rod repair in the same area. I have a tip for my torch that's rated for 1"...should I even bother trying, or look at another avenue for repair, refab of part.

    I can post pictures if needed, but really just want to know if it's possible to cut cast iron and built up weld. This is s structural repair...a broken foot pedal arm on an old heavy duty hollow chisel morticing machine that gets a lot of use fwiw
    S_W_Bausch and John Madarasz like this.

  13. #13
    getth is offline Plastic
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    Quote Originally Posted by S_W_Bausch View Post
    This thread is years old, but I can add this:

    Handbook-Manual Cutting

    Where it is said:

    It is make easy to learn plasma cutting

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