I am making an annealing "oven" for nylon rod out of a piece of 4" stove pipe wrapped in fiberglass insulation. The rods will be suspecded vetically in the pipe, and it will be heated with a heat gun from the bottom. Nylon anneals at ~ 350F, but the termperature will be a bit uneven, so places may get a good bit hotter.
BEFORE EVERYONE GOES OFF ON A TANGENT ABOUT 16 DIFFERENT WAYS TO DO THIS, DON'T BOTHER. THAT'S NOT MY QUESTION. (Sorry, but I'm tired of everyone trying to ignore my actual question in favor of redesigning _everything_. I've had a cold for days, and I'm a bit testy..).
I will support the pipe from the side with a chemical ring stand setup. To minimize the heat lost through the suspension system, I need something that is a good thermal insulator to go between the 1/2" diameter metal support rods and the stove pipe. My default will be threaded ceramic spacers, which I can pick up from Mcmaster Carr, but they are over $4 each. Not fatal by any means, but mildly annoying.
If I knew of a good insulating material that could take the heat, I could machine the spacers myself, but the only plastic I'm aware of that is good to higher temps is teflon, but McMaster says it is JUST good to
500F. It's also not the best material from a mechanical rigidity standpoint. I have some & might try it, but I was wondering if there was some material that I'm overlooking.Thanks for comments & ideas.
Doug White