Homemade Bending Iron : Diameter? Metal? Temperature?

[Ciaran Cosgrave]

I'm planning to make a homemade bending iron. What would be the ideal diameter of pipe to use and what is the best (if any) metal to use? I presume aluminum has too low a melting point.

I plan to use a heat gun as my heat source. It can produce temperatures of up to 600° C or 1112° F. I presume this is enough heat. Is it?

[Jim McConkey]

The diameter of pipe depends on what your needs are and what kinds of instruments you will build. You want one as small as the tightest radius you need to bend. If you build violins, that is much tighter than if you build guitars. Some commercial benders a cross section similar to an egg or airplane wing, so that there are both broader surfaces and tighter radius areas for smaller parts. Some benders have a large pipe, and have smaller diameter pipes that can be attached. At least one inventive member here used part of an aluminum sailboat mast, which has an ovoid cross section. And, no, aluminum is fine. It melts as 1,221°F/660°C, and it only needs to get to get hot enough to flash boil water. 375°F is a good start, which the same temperature you cook pancakes at. The standard test is to drop some water on the pipe and see if it dances around. If you get much hotter, you start scorching the wood. See if that heat gun has a low setting, or get a dimmer for it.

[Ciaran Cosgrave]

The diameter of pipe depends on what your needs are and what kinds of instruments you will build. You want one as small as the tightest radius you need to bend. If you build violins, that is much tighter than if you build guitars. Some commercial benders a cross section similar to an egg or airplane wing, so that there are both broader surfaces and tighter radius areas for smaller parts. Some benders have a large pipe, and have smaller diameter pipes that can be attached. At least one inventive member here used part of an aluminum sailboat mast, which has an ovoid cross section. And, no, aluminum is fine. It melts as 1,221°F/660°C, and it only needs to get to get hot enough to flash boil water. 375°F is a good start, which the same temperature you cook pancakes at. The standard test is to drop some water on the pipe and see if it dances around. If you get much hotter, you start scorching the wood. See if that heat gun has a low setting, or get a dimmer for it.

Hi Jim,

It's guitars I'll be building. Does the use of an ovoid iron not lead to unwanted bending or bending in an unwanted direction? What I mean is, if you're bending a side, you want your bends to be along the length of the piece but you want it to remain flat across the width. Would you no get warping or curvature across the width?

[Peter Wilcox]

Ciaran - here's a thread from the archives on benders: http://www.mimf.com/library/Many_homema ... -2012.html

I made one from some cans and a heat gun - the last one in the thread. Initially the blowback started melting the plastic around the mouth of the gun, so I set it back a couple of inches and the heat burned the wood the cans were mounted on. I faced this with hardiboard, but eventually the heat charred the wood again, so I bought a charcoal starter and used that inside the cans. It got a little too hot, but I just lived with slightly scorched sides.

I need to build a better one with a pipe and temperature control.

There may be other information available on this and other things in the archives that were recently put up here - access it using the library search: http://www.mimf.com/nl-ksearch/ksearch.htm

[Clay Schaeffer]

I'm sure Jim meant oval in cross section. That shape works better than one that is round in cross section, although plenty of people use round pipes. Thicker pipes hold heat (which is desirable) better than thinner ones.

[Ciaran Cosgrave]

The diameter of pipe depends on what your needs are and what kinds of instruments you will build. You want one as small as the tightest radius you need to bend. If you build violins, that is much tighter than if you build guitars. Some commercial benders a cross section similar to an egg or airplane wing, so that there are both broader surfaces and tighter radius areas for smaller parts. Some benders have a large pipe, and have smaller diameter pipes that can be attached. At least one inventive member here used part of an aluminum sailboat mast, which has an ovoid cross section. And, no, aluminum is fine. It melts as 1,221°F/660°C, and it only needs to get to get hot enough to flash boil water. 375°F is a good start, which the same temperature you cook pancakes at. The standard test is to drop some water on the pipe and see if it dances around. If you get much hotter, you start scorching the wood. See if that heat gun has a low setting, or get a dimmer for it.

Hi Jim,

It's guitars I'll be building. Does the use of an ovoid iron not lead to unwanted bending or bending in an unwanted direction? What I mean is, if you're bending a side, you want your bends to be along the length of the piece but you want it to remain flat across the width. Would you no get warping or curvature across the width?

1 day later - I've just seen a photo of the airplane wing type iron you mentioned. I get what you mean now. It's shaped like an egg if you look down on the top of it but not literally shaped like an egg. Ignore my previous question. I was taking you very literally and had visualized an actual egg shaped iron which made no sense to me at all!

[Clay Schaeffer]

Hi Ciaran,
Like you, I focused on the three dimensional ovoid, and skipped over the "cross section" part . In my haste to clarify things for you I rather made them a bit more muddled.

( My apologies Jim)

[Jim McConkey]

No apologies necessary, and I'm sorry work travel has kept me away from the computer to answer any earlier.

Round pipes work fine for most guitar work. Other than cutaways, there are no tight bends. I build some smaller instruments with tighter curves, so an ovoid or multi-diameter pipe works best for me. My first bender was an industrial strength plumber's soldering iron held in a copper pipe with copper wool. A little creative hammer and vise work turned the plain tube into a more ovoid shape. Just before I moved I managed to pick up one of those commercial temperature controlled, ovoid aluminum luthier's benders, but I haven't had a chance to try it out yet since most of my shop is still in boxes.

[Bob Gramann]

I do my really tight bends by rocking the point of the bend (with an aluminum strap) down on the pipe (bend away from the pipe) after I start it with the pipe inside the bend. You don't need a small diameter pipe.

[Tim Allen]

Following suggestions on the MIMF, I made a bender using an electric charcoal starter as a heat source. A cheapo router speed controller functions to adjust the heat. I suppose you'd seldom forget and leave a torch or heat gun running, but the charcoal starter is pretty much silent, so I have a timer on it. I don' t think I'd forget, but better safe than sorry.

I went to a building materials recycling center (we don't have "junk yards" in the Bay Area, heaven forbid) looking for a pipe, and came away with a piece of aluminum conduit, about 4" in diameter with 1/4" thick walls. I was able to bend it a bit by pounding it with a sledge hammer so it has an oval cross section. The charcoal starter is just jammed in there. Aluminum flashing serves as a baffle to keep the heat in.

Ditto on spraying water to check temperature: when it sizzles for a couple seconds before it evaporates, the temperature is right.

[Joe Williams]

This is such an old thread, but I'm here so what the hell. I'm new to this, just starting my second. I just made a bender using a short piece of 3" exhaust pipe from the auto parts store and a propane torch stuck inside. Seems to work very well.

[Tim Allen]

Great! Have some fun bending sides!

[Eric Baack]

I took a piece of 1.5" diameter brass rod and bolted it to a piece of phenolic and bolted that to a piece of aluminum then screwed it all down to a base. I have a temperature controller and 3 cartridge heaters in it. Works fairly well and can actually heat the rod up to 600 degrees if I wanted too. I've been bending some fairly thin stuff to laminate sides on a custom case.

[mark forsell]

Don Teeter has plans for a bending Iron, Or pipe, mounted on a stand in his book The acoustic guitar. Plenty of ideas and plans for making homemade tools and fixtures of all kinds. I've made a lot of them and they work well. He is a toolmaker by trade as am I, so that helps. But I think anyone with any mechanical abilities can make the stuff.