MIMF

I use both a big "black iron" pipe, and a smaller galvanized pipe. We don't get the galvanized pipe hot enough to off-gas the zinc. as for smoothness, i give the pipes a "shoe shine" treatment with emery cloth before each session, so they're pretty durn smooth.

What those who haven't used a torch need to realize is that we don't run the torch on full-tilt-boogie, WFO, flame-thrower output, but rather, it's on a rather low flame. best thing about it is that the torch makes a sound, and you can 'tweak' the temperature just by the sound of the torch...

Seems like I remember it takes about 700° for galvanized pipe to be hazardous, but I don't remember if that was Farenheit or Centigrade
At any rate, it was well above normal bending temperatures.

i have a black steel pipe and i have about 8 sides done with it and no sign of running out of gas, i'm in the wipe down camp ( mind you my instruments have few bends than most as they are tear drop shaped), i'm bending birch... i have also done some bending of 1/8" maple and walnut for jewelry and from what i've found it's a huge matter of patience. if i push the wood it cracks if i go slow ( with the thicker stuff painfully slow occasionally) i can bend flawlessly even so much as making a ring (clamped a 1/2" copper pipe in the end and used that to bend on). i got into trouble when i felt like i was adding pressure or heating too small an area. move the piece about 1/2 in all directions to get the area around the bend to relax you shouldn't need real force to bend it it should kind of "let go" when i've used that even flatsawn stuff has let me do some pretty tights bends on it.

I would also add that you should try to get an even heat distribution cross the bending surface of the pipe. If you play with the angle of the torch entering the pipe, you can have the flame heat more evenly from the front to rear of the pipe- otherwise you'll get a hot spot in the middle, which runs the risk of charring, while the edges don't get hot enough to bend- risking a crack.

And I would double-agree that thickness of the wood has a huge impact.

Incidentally, my father designed this propane bender, which uses a 1/2" manifold tube to distribute heat totally evenly- with this improvement, I can now confidently bend many species of wood totally dry (myrtle, apple, walnut, cherry) and tough-to-bend woods go much smoother (such as doug fir).

(You can't quite see but there are 9 equally spaced holes drilled across the top of the manifold tube inside the bending pipe)

Your burner tube is kind of like what's on a Weber gas grill? Very cool....or hot. <bg>

Right! That's where we got the idea

I haven't bent a ton of sides but I've often wondered why people use a propane torch when a lightbulb provides so much more even heat. I used a thermocouple to measure surface temp and couldn't get an even temp with a torch. I switched to a 200W bulb and had terrific results. I do think the guys who said don't soak overnight are steering you straight. Too much moisture seems to make the sides want to be wavey in the guitar top to back direction (where you want them flat).

Ron Belanger wrote:Go slowly. Get the pipe hot enough for a drop of water to not only sizzle, but bounce around on the surface of the pipe and keep it that hot. Gradually rock and move the side over the hot pipe to heat it. You will feel the wood relax when it is ready to bend. Do not force it. PRACTICE ON SCRAP!!

Keeping it hot enough is the trick. If you don't have a termometer then do as Ron says - dribble a little water on the iron (from a sponge for example) and the little drops should perform a wonderful sizzling "dance" for you. Little drops dancing up and down. Once you see the dance you'll recognise it. If the water forms "puddles" and boils/evaporates off, it is much too cool.

The thinner the wood the easier it bends too. But you must let it get hot enough before you put pressure on it. Too much pressure too soon and it snaps. If you spend too long trying to bend it (because you haven't got the pipe hot enough) it seems that the wood gets brittle and cracks even more easily. Bending one side shouldn't take more that about 9-12 mins. If its very thin and co-operative you can probably get it to 3-4 mins a side for some easy to bend woods.