Problems with oxy fuel cutting.

[DDoug]

I tried everything when I was attempting to cut 10 or 11 gauge sheet. Hot and fast doesn’t mean anything unless you have some evidence to back it up? What size tip and how fast was the travel speed?

11 is 0.132 and 10 is 0.118 and that is quite accurate when I measure my sheets.

I was cutting brand new clean sheets and there is no way I would be removing mill scale before cutting any new sheet.
The torch on a CNC needs to be exactly vertical, not practical to angle it 40° unless you are only making straight cuts. The OP was hand cutting so could apply to his situation. However keeping a torch angled correctly around a circular shape is quite difficult. Those that suggest the method should try it first on a round shape.

" Hot and fast doesn’t mean anything unless you have some evidence to back it up?"
Uhm...am I on trial here ?...
It works, I did it, repeatably, and got good parts.

I run Oxy propane, and I run Nitto Koiki hi-speed tips.
I don't recall my settings, But I did follow the chart.

You can change your pre-heat flame a rather large amount for each tip size.

As far as new material, hot rolled has scale for even that thin of material, yes it's very tightly adhering, yes it's smooth.

but it still is scale.

 

[Wlhequipment]

I tried eveything guys, everyone's suggestions I'm sure are valid, but nothing worked at all for me. Hot, cold, fast, slow, scale, no scale, smooth side, diamond plate side, preheat, no preheat, higher pressure, lower pressure, I even tried a couple tips. This is just going to remain a mystery for me. I've made the part I need to make, so the point is kinda moot, but it's frustrating not to know what's going on, in case I run into this again. With the exact same setup, I can go from cutting 16ga to 3/8, and be fine. A little sloppy on the 16ga, and a little slow on the 3/8. but it cut. Why the hell not the 1/8? Some wierd alloy? Chinese potmetal? Tinfoil hat? It's probably the crack I had for breakfast.

 

[cyanidekid]

some things shall remain un-knowable... some of us do appreciate your responding with your results, even if you didn't get it sorted..
one thing left, try a different piece of that thickness.
...and so, Canuckian steel gauge is different than US???

oh, and im not saying routinely remove the scale on everything, but if and when you are having a particular problem. if you were doing precision cuts, you would probably be using pickled and oiled sheet anyway.

 

[memphisjed]

Diamond plate can be a588/847 (corten). The copper means you melt and not burn the metal. Or you got some with high chrome from the rebar rot gut mill.

 

[M. Moore]

Memphis,
I have cut 1/2” and 3/4” Cor-ten steel and it cuts fine with normal gas pressures and cut speeds using oxy-propane. So I don’t think it has anything to do with copper in Cor-ten steel. I had the exact same problems with 10 and 11 gauge steel and I was using a cnc.

Cyanide, the point was that there are no steel sheets marketed and sold as 0.125”, there is only 10 or 11 gauge which are not listed as 0.125” in thickness.
Coming from the wood industry it is just an oddity that defies explanation. Switch to aluminum and they do have gauge sizes to 0.102“ and then bingo 0.125”!
Hot rolled flats start at 0.125” but obviously do not match any gauge sheet sizes.

 

[BT Fabrication]

I tried eveything guys, everyone's suggestions I'm sure are valid, but nothing worked at all for me. Hot, cold, fast, slow, scale, no scale, smooth side, diamond plate side, preheat, no preheat, higher pressure, lower pressure, I even tried a couple tips. This is just going to remain a mystery for me. I've made the part I need to make, so the point is kinda moot, but it's frustrating not to know what's going on, in case I run into this again. With the exact same setup, I can go from cutting 16ga to 3/8, and be fine. A little sloppy on the 16ga, and a little slow on the 3/8. but it cut. Why the hell not the 1/8? Some wierd alloy? Chinese potmetal? Tinfoil hat? It's probably the crack I had for breakfast.

melting back together is 99% of the time that the travel speed is too slow. basically that thin is as fast as you can drag it. As you get thinner you need to angle it more towards the material to be cut. how long is the star pattern on a plate when set?

 

[cyanidekid]

Memphis,
I have cut 1/2” and 3/4” Cor-ten steel and it cuts fine with normal gas pressures and cut speeds using oxy-propane. So I don’t think it has anything to do with copper in Cor-ten steel. I had the exact same problems with 10 and 11 gauge steel and I was using a cnc.

Cyanide, the point was that there are no steel sheets marketed and sold as 0.125”, there is only 10 or 11 gauge which are not listed as 0.125” in thickness.
Coming from the wood industry it is just an oddity that defies explanation. Switch to aluminum and they do have gauge sizes to 0.102“ and then bingo 0.125”!
Hot rolled flats start at 0.125” but obviously do not match any gauge sheet sizes.

yes, I agree on the absolutely ridiculous irrational nature of sheet and wire gauge standards, and it's actually much much worse than you have seen so far!
the steel sheet gauge standards were historically derived from weight per square foot arbitrarily assigned numbers, and not from thickness.
apparently its different in Canada and the USA? I wasn't aware of this, but maybe north of the border, the British standard is still in common usage?(11Ga. is .1205 US, and .1160 in British standard wire gauge, I have no idea where M.Moore's .132 comes from).

the non- ferrous gauge is of course completely different, and based on a gauge plate made by Brown and Sharpe in the mid 1800s, and is also seemingly arbitrary.

take a seat and hold on, for example 16 gauge is;
in US standard steel sheet gauge, .0598,
in US steel wire gauge its .0625,
in British standard wire gauge its .064,
in Brown & Sharpe (non-ferrous) its .0508,
in music or piano wire its .037,
in Birmingham or Stubs its .065,
in Birmingham Gauge for sheets and hoops its .0625
in Stubs steel wire gauge its .175
in galvanized sheet gauge ts .0635,
in zinc gauge its .045