I've been using an old piece of 2 1/2" black iron pipe clamped in a pipe vise, heated by a hand-held torch for bending, and it works pretty well. But I've been hankering for a larger-diameter (or even teardrop or oval) shaped bending iron to get some curves smoother. I was in HD yesterday, and picked up the hardware to make another bending iron using a light bulb as the heat source (picked up 150 and 200 Watt incandescent bulbs at the same time). As the actual iron, I picked up a length of galvanized dryer vent and a cap.
I know that galvanized iron can cause zinc poisoning if it's heated to above 700F or so, which is why you need to be really careful welding it. I don't expect a bending iron to get anywhere near that, though it could easily get to above 200F, even using a bulb as a heat source. (After I'd bought a regular light switch, it occurred to me that I could have bought a dimmer switch instead, but for now, my "thermostat" will just be putting in stronger or weaker light bulbs, as I practice with it...)
Googling shows a number of examples of DIY bending irons that people put together from galvanized pipe, and I've never heard of anyone suffering from zinc poisoning from using one. But I thought I'd ask here:
Has anyone had experience with using galvanized as a side bending iron? Have you heard of anyone getting sick from doing that?