Many homemade bending irons [Pictures] - created 01-09-2012

Polk, Doug - 01/09/2012.19:50:59

So I have been trying to find discussions on making your own bending iron for violins. Seems that I've seen a post in the library for making one from a length of 4" pipe with a 200 watt bulb inside, but I can't find it anymore. Any ideas? Thanks!

Here is a quick sketch of my 4 inch bending iron.

1/4 inch pipe. About 7-8 inches long. I heat it with a charcoal starter. It leaks quite a bit of heat out of the open end, so I covered this with a light piece of tin.

I use my steel vise to clamp this. Use a router speed control for heat control.

I actually had the welder make me an oval bender.

I don't use the oval bender as much as the 4 inch round.

I also purchased a 5/8 inch cartridge heater on Ebay.

I clamp this in the vise and use the router speed control also.

To use the cartridge heater with a larger diameter, I slip a piece of 1 inch or 1 1/2 inch conduit over the cartridge heater.

The cartridge heaters (got mine from McMaster-Carr) are awesome. I got a 1000deg heater controlled with a 1000w dimmer. The cartridge is in an aluminum pipe filled with sand (sealed on the ends, obviously). Takes a while to come up to temp, but stays there.

Mine is very much like Steve's. The pipe came from LMI many years ago but it is available at my local welder's shop. The 500 watt charcoal lighter was $15 at Lowes. I had to bend it (while it was red hot) to make it fit. The dimmer is a standard 600 watt lamp dimmer. The end of the pipe is sealed with an aluminum pop can end jammed in. I bolted a two-by-four to one side of the pipe and use the wood to support it. Once, in many years, I had to tighten the bolts to make up for the char that consumed the wood. To do the C on a violin, I heated the wood on the pipe but bent away from the pipe while holding the center of the bend to the pipe to get the bend tight. To get s small radius bend, I tried bending on a 3/4" copper pipe heated by a torch but it wasn't very satisfying. Bending on this pipe is one of the parts of building that I enjoy the most.

Doug, it is possible you're thinking of mine. It's not unique, but I have posted it here before.

It's actually a 3" copper pipe (scrounged from the scrap dealer) some reduction fittings scrounged from the plumbing supplier, and a narrow pipe length from my neighborhood hardware store. All of this just friction fitted together, no solder (the heat would probably melt it anyway). It's mounted on some scrap steel to elevate it and allow for a lot of air flow underneath (I'm freakish about fire hazards) and it has a 250 watt bulb inside for heat. Connected to a rheostat, but in use I always crank it up wide open, so the rheostat is probably not necessary unless you've got some really big wattage inside.

Here's another view, but I'm not sure it reveals too much more. There's a ceramic socket inside. The wiring comes down through some hollow threaded lamp tubing. This is my attempt to protect the wiring from the heat inside the copper pipe. Takes about 20 minutes to heat up, then it's ready to bend anything. It's all screwed to an MDF base, which I clamp to the workbench or my table saw top in use.

Truck tail pipe section, cut in half, then the extra piece split lengthwise about 1/4" with a hacksaw, then squeezed into the other piece. The tail pipe is bigger at the back end where I split and bent the flanges out for mounting. Inside is a charcoal lighter controlled with a HF Router Speed control. It has worked well for 10 guitars, so far.

Mine looks almost exactly like Bob's accept I haven't plugged the end and my "control box" is a 3 fixture box with a hot tub timer switch then a dimmer switch then an outlet; I don't have to worry about forgetting to switch it off. . . I'd like to make one (or an attachment for this one) that allows me to bend a tighter radius. I have done as Bob describes and bent the opposite way but that is frustrating with certain woods that don't like to bend. I'm not sure what to use for a heat source though; I don't think a charcoal lighter will bend enough for the narrow pipe and I don't want to use a cartridge heater that draws too much current for my dimmer. . .

Hey, Waddy, I really like the addition of the oven thermometer to yours. At least that's what I think I am seeing. I also like the charcoal lighters you guys are using, because it's highly unlikely that I'm going to be able to replace my lightbulb when it burns out. Nice ideas, guys.

I don't think it's very accurate, but it gives me a neighborhood, if nothing else. Thanks!

Hi Doug, i've made two with 500 watts hazlogen tube type light bulb, in a round pipe, and the other with two ceramic screw socket and screw type 200 watts halogen light bulbs into an eliptical piece of stainless steel pipe. Easy. Thought i've never dared to fill them with sand or anything else.

I built this one using a 300W halogen bulb - one of the long skinny ones from a cheap floodlight. My thermometer is a spray bottle of water. I just give the pipe a spritz and when the water dances off it is hot enough. If it starts to burn I turn it down a hair, but mostly it is just barely hot enough. I think I may step up to a 500 watt bulb when this one burns out. The end of the pipe is plugged with a piece of bent aluminum flashing.

This discussion got me thinking more about cartridge heaters. I did a quick look and noticed that I can get them in 110v and a low enough wattage (500ish W)to run through my dimmer-switch/hot-tub timer set-up and they are pretty cheap. So I did a little more searching and found reference of people using cartridge heaters in the 150-200w range (110v). That seemed low, but what do I know. Does anyone have any experience with these?

Bryan,

Mike

Thanks Mike! I'm starting to wonder if something smaller, say 300w would get hot enough. Do you think that your 600w heater is over powered? Do you come close to using full power?

All, do these need to have full contact with the bending iron or can I just put one on a pipe like I have done with my charcoal starter?

I preheat on high and turn it down to 200, if you check the specs of the cartridges, at least the ones mentioned in McMaster, they are all rated for the same maximum temp. They need to be inserted into a fairly tight hole however as they need full contact with the iron to do the job well.

Mike your bending jig is as nicely machined as your guitar parts! Makes my bender look like something from Colonial Williamsburg.

I'm wondering now if I can repurpose the ol' George Forman grill I have laying around...

I have a hard time believing a French curve shape would heat evenly, because of the constriction at one end. An ovoid, or egg-shaped, cross section gives you just as much flexibility for bending, but without the uneven heating problem. I have seen some squish a round pipe to make an ovoid, and others have cut off sections of an aluminum ship's mast, which apparently comes in the right size and shape already.

This pic shows the end of the heater cartridge. The original shape of this was round, but a tight bend for a LP style guitar pushed me to modify the contour. I thought I would need to make another for larger radious bends, but this still works fine. The aluminum cuducts heat very well, there are no cold spots.

I put this over on the MIMF-TNG, but figure I might as well share over here since it's relevant and I haven't posted in awhile. Mine is a baseball bat from the thrift store, which is about 2.25" diameter. The handle section is closer to 1" and I intend to make a second one from that.

Heat source is a charcoal starter bought at the end of the season when they were on sale for $9, which is good because I broke the casing on the first one while trying to bend it to fit the tube. As someone else pointed out... heat the starter before trying to bend it, and I used a pipe for the inside radius and out of paranoia I used a bending strap to keep from stressing the outside of the bend.

The backer is concrete tile backer left over from a remodeling project. It needs to be backed up with something... I've got a second one cut for when I get ready to use it again... unfortunately I don't get much shop time.

The inside of the bat is also filled with BBs, I'm not sure why... it just seemed like a good idea to increase the thermal mass. Since I don't have temperature control on it yet, I get it to temperature and then uplug it and it maintains its heat for quite awhile.

the baseball bat idea is good,,,i hvae two old large tip elect soldering irons,,,placing one in the bat may work...

I don't believe a soldering iron will make the aluminum bat hot enough.

Depends on the size of the soldering iron. You may be thinking of the soldering irons for electronics, but there are bigger ones for plumbing, etc. My old bender was powered by a plumber's soldering iron and it got plenty hot enough.

Hint: Get a couple copper scouring pads and stuff them between the soldering iron and the pipe and you will get better heat conduction.

"Hint: Get a couple copper scouring pads and stuff them between the soldering iron and the pipe and you will get better heat conduction."

I like the copper scouring pad idea. The BBs I used in mine give me an even heat distribution, conduction, and a lot of thermal mass, but the copper scrubber pads would be easier to keep from falling out and would result in a MUCH LIGHTER bending iron.

I agree that the copper pads are a great idea for helping conduct the heat. Never thought of it myself!

Be aware that many(most?) "copper" scrubbies sold today are copper-plated steel, and not solid copper, so these won't conduct heat any better than a plain steel wool pad. Look for solid, or pure, copper scrubbers. They cost more, but will work way better. If you have a good garden center nearby, they may also have copper mesh, which will work even better. The copper mesh is used to keep slugs at bay.... Lee Valley Tools sells it, if you can't locate any locally.

The BBs are a great idea, too. Copper-plated steel scrubbies may not conduct heat any better than steel wool, but steel wool tends to rust and the scrubbies do not. In any case, any of these metal fillers do better than just air.

Bob Gramann, I found a charcoal lighter on the Kmart website. The handle looks very much like the one in your pic. Wondering if it will work? Also, did you have to bend the element to get it inside your pipe? And was that a problem? Thanks!

To bend the element to get it inside the pipe, I plugged it in, let it get red hot, and crushed it in a metal vise. It contacts the sides of the pipe. I use no packing in the pipe which seems to have enough mass to keep a stable temperature once its hot. I looked at the Kmart website--yep, that looks just like mine. It's rated 500 watts. My lamp dimmer is rated 600 watts. For most woods, for me, the temperature is just right when the dimmer is dialed 3/4 of the way around.

I would not use steel wool inside a bending iron as it is somewhat combustible.

I would not use steel wool inside a bending iron as it is somewhat combustible.

Oh yes, good memories there, a few pounds of steel wool and a microwave radar transmitter

A can of beans, a can of dog food, and a paint stripper.

Another view.

In my initial build, this part burst into flame after about 15 minutes - pressure treated doug fir. I made another of alder and fronted it with a piece of hardiboard which seems to be holding its own.