I'm restoring an antique cast iron stove that was apparently overheated at one time as one of four cast iron grates are bent. I'm wondering if I can place this bent grate into a charcoal fire till it's red hot, bend it straight, then return it to the fire and let it cool slowly as the fire cools over many hours? If not advisable is there an established proceedure for straighten deformed cast parts like that described above?

If it is a true antique, correct age and all that, don't try to straighten the grate it will almost certainly break and then you have devalued the antique.

I have worked with cast iron and have never successfully bent it. I think the reason these grates bend is because it happens very slowly at a high temperature; over weeks or even years. You idea might work but I would support the grate with fire bricks below with a heavy block of steel on top. The weight on top would do the straightening and the bricks underneath would stop it going too far. In theory anyway, I think I would live with the bends.

mmm this is interesting....

i like Geof's idea... using constant weight to "relax" the bars... i wonder if you could heat it with some oxy acet... (very slowly)

maybe the best thing would be to get a small sample of cast iron and heat try to bend that one...

davef,

although I havent tried it, I would be inclined to heat it cherry red in your charcoal fire/forge and the press it flat very slowly, reheating frequently. I have built presses using hydraulic bottle jacks in a welded rectangle of small "I" beam or channel. I suspect that a scissor type car jack would be sufficient, the idea being not to put too much pressure on it, bit at a time, re-heat cycles and let it cool with the fire. You will have to have a fire big enough to heat the whole grate evenly.

Matthew