bending bamboo

hi Ed, I bend bamboo with dry heat from the inside of the bamboo. After heating the bamboo I put it into a form for some hours.

Glue-shaping is kind of risky, cause the glue line is stressed much more.

Good luck, Michael

thanks I will try that for the other limb :) I have the backing on (flat longbow), but trying to get the bamboo to bend into a fade out on the belly is real hard. One side I have done but have a small split on the fade out. I don't think this will affect it except for looks. Being able to bend bamboo well might make recurves etc possible for me, and eventually maybe something more severe along the short asiatic bows.

well I tried the dry heat. A friend also said this works well, but buggered if it worked for me. SO a few questions:

how hot? I took mine to the point it started to colour and was rather too warm to touch. Any hotter and I think the edges might have caught fire.
How malleable does it become? The blacksmith I talked to about it told me it gets quite soft, whereas for me it only softened a little and I was still worried it was going to split as I clamped it to shape - it needed clamps to get to even a mild bend.
Does it need heating for a time period?

Any hints or better yet pictures/descriptions of how others have done it would be much appreciated. I am looking to make a few longbows to start with and then recurves before going for the asiatics

Ed; I have bent bamboo backings for recurves on a gas stove, with no problems. The exact place where the bend is desired only is heated by roticerating over a mediun fire at about 6 inches above the flame, less heat is better than more. The heat must penetrate evenly and to the center of the wood. No reason to scorch the bamboo, it does not need that much heat, and scorching shows a certain lack of control. At the right heat an odor of grass is present and wax begins to ooze from the skin. When held just in front of the lips the radiating heat can be felt. It will take about as long to cool as it took to heat, half a minute or a minute, so no need to hurry.

If one starts with a flat surface on the inside, then heat recurving will cause the flat surface to bulge slightly. Keep this in mind for gluing.

Gentle bends might not require prebending, such as in Japanese bows.

I was a bit shocked to see on video the Korean bowyer score the inside of the bamboo core diagonally with a knife and bend green. This would seem to be a technique which a master could do but might be difficult for others.

sounds like the Korean bowyer had a few more fibres than he needed for bow integrity :)

Tried again but no luck. I think it might have something to do with how old and aged this bamboo is. I will try it next time on a newer peice and see how it goes. Is there anywhere a site where this is shown (even better an mpeg)?

I have several giant bamboo peices with a slight bend in them that need straghtening to be good for bow backing. Also will try an indian style all bamboo bow as the wall are about 20mm thick! The rest will get bandsawed for backings and core laminations.

I noticed in Thomas's video that the Korean bowyer cut away more than half the bamboo core after he had glued the horn to the belly. I guessed from this that the original thickness was more for handling than for the finished bow. The sacrificial top layer of the inside surface of the bamboo could be scratched and marked by the binding on of the horn but it wouldn't matter because it was removed before the sinew was applied.

I think these old bowyers knew a few more tricks than we have found out yet.

The Korean bowyer uses a kind of jig to make sure the bow keeps the same shape with the bamboo and the horn [ C - shape ]. Once the horn cooled down he takes off the ropes and starts with the other limb.

R