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