Make a tight radius bending iron

[Bob Gramann]

I have a 2 3/8” pipe with an electric charcoal lighter inside that I use for most of my bending. I sometimes bend tighter radiuses by heating the outside if the bend. I decided to make an iron with a tighter radius. I have the pipe and the heat cartridge shown in the picture below. Unlike the charcoal lighter which itself was bent to fit the pipe, the cartridge has nothing intrinsic to hold it to the pipe. I can imagine using springs or wedging a couple of pieces of metal between it and the other side of the pipe. It would be nice to get something that would transfer heat all around the cartridge. Has any one solved this before? What did you do?

IMG_0172.jpeg (43 KiB) Viewed 16324 times

[Peter Wilcox]

I stuffed steel wool around my charcoal lighter to transfer heat to the pipe. Maybe it would hold the heat cartridge in place if stuffed in very tightly.

[Bob Gramann]

Thank you. Sounds easy enough to do. I’ll give it a try.

[Jim McConkey]

Steel wool unfortunately oxidizes and rusts easily. I use, and would recommend, the copper scouring pads you can find in almost any kitchen department. They conduct heat really well (better than steel) and do not oxidize. My pipe still has the original copper stuffing from decades ago.

[Bob Gramann]

Thank you, an even better idea.

[Bryan Bear]

This has been on my to do list for a long time and I have thought of how I might approach this problem. The plan in my head was to wrap aluminum foil as tightly around the cartridge as I could and jamb it in there aiming for as tight a fit as I could achieve. I figured aluminum conducts heat pretty well and a tight wrap would reduce voids as much as possible and give as much metal to metal contact as I could get.

I had considered the steel wool but steel isn't a great conductor of heat compared to aluminum and copper. I hadn't considered the copper scouring pads; that might be the best approach.

Edit to add:
Thinking about this a bit more, stuffing a bunch of copper scrubbers would probably really benefit my current pipe which is just a chunk of steel pipe with a crimped charcoal starter in it. It takes a while to get to temp and has hot spots. Where the element touches the wall of the pipe is noticeably hotter. The copper scrubbers would better distribute heat from the parts of the element that are hanging out in the air and carry it right to the walls of the pipe.

I just looked it up and difference in heat conductivity between Copper (and to a lesser extent aluminum) and steel is larger than I thought.


Common metals ranked by thermal conductivity
Rank Metal Thermal Conductivity [BTU/(hr·ft⋅°F)]
1 Copper 223
2 Aluminum 118
3 Brass 64
4 Steel 17
5 Bronze 15

[Bob Howell]

A friend is making one and directions he found said use Al foil. He found supply of Al shavings on some site for maybe $20. Pack it in and drill hole. Some site had discussion of technique.

I'm looking for the heating element as 10 years ago a water heater element was suggested. My friend is traveling for summer and I am ready to proceed. Seems an online store which means Chinna. Any other source?

I got the pipe in 2 sizes, mounted and heated with propane torch. Making upgrade.

[Bob Gramann]

For my big one, I used a 500w charcoal lighter from Lowes. I had to get it hot and bend it to fit it in the pipe. This little cartridge (200w) was $10 on Amazon. I used to use a propane torch but went to electric to avoid the fumes.