Question about bamboo

[Simple Hunter]

 
       My question is, if I was going to try bending bamboo what is the best method, steam or dry heat?
 
               Thanks for any comments

[Pat B]

What is the purpose of the bend?   recurve, R/D, straight reflex?  Most of these can be bent at glue up time with clamping pressure. A recurve might need to be assisted with heat and dry heat used cautiously will do the trick. Once thge boo hits a certain temp, it becomes very plastic and bends easily.

[Simple Hunter]

      Thanks, Pat. Ok I dont know if this is a good idea or not but I was thinking of using the outside of the boo as the belly and using sinew on the back and maybe recurving or RD the limbs.Any thoughts would be welcome.  thanks

[JW_Halverson]

If you are thinking along those lines, you might want to research rattan for the bow.  Rattan is similar to 'boo and nearly indestructible.  The bows are tillered from the back, which is the cut side of the rattan.  Tillering is easy once you have a string on it.  Just slap the back down on a belt sander and sand off the flat spots, pull 20 times, pick a new spot to sand and repeat as necessary.  Since you don't have to unstring to tiller, it can be finished in almost no time. 

Mike Stocklin in Faith, SD has made short plains style reflex/deflex with sinew over the backing and made up to 80# draw at 16"! 

[Simple Hunter]

          Thats good information.  Where would I get rattan? I already have a large piece of boo.  thanks again

[Pat B]

Bamboo, if heat treated, makes an excellent belly. James Parker(Robustus) builds boo back and belly bows that are incredible. I think a sinew backing would go well with boo belly. Are you planning on a core wood or only sinew backed boo?

[Simple Hunter]

     
Thanks for the reply Pat, I was thinking of just sinew on the back but you have me thinking...when heat treating boo would you do it like hickory?

[Simple Hunter]

          Another thought, after applying the sinew how would you tiller the belly?

[Pat B]

I was at James' house one day when he was heat treating bamboo. He used a propane powered rosebud tipped torch and was scorching the heck out of the boo. As he moved down the strip of boo it would flame up behind him and when done the boo was black and still smoaking.
  You have to pre tiller the boo and I guess add the sinew until you get to weight. Some final tillering would be done by scraping along the sides of the bow.

[Simple Hunter]

    Thanks for the info. You guys are awesome

[markinengland]

Quite a few bows in the far east were not horn/sinew but bamboo sinew. Bamboo just as you describe with the rind side of the bamboo as the belly and heavily sinewed and recurved etc.

Should work just fine. If they could do it then we can do it now!

[JW_Halverson]

If the back of the bow was heavily sinewed and the belly was the rind side of the 'boo, how would you tiller?  I think that was your question?

I think you would tiller from the back of the bow using heavy sandpaper to thin the sinew.  Once you hit tiller, wipe down with a damp sponge or cloth, let dry, and then brush a lite coat of hide glue over the whole thing.  And since I am so fond of it, I'd them lay on a course if thin rawhide over the sinew.  Done.

[oat]

Having sinew back and bamboo's skin on belly shouldn't be bad idea. It had been used centuries ago in the east (chinese/korean).
From many video, bending are dry heating until oil/steam come out. You may need to flatten the concave part a bit.

For the bamboo belly, unlike the horn belly, you will have no room for material removal.
Tillering might be patching sinew on the back til you get the required poundage.

My korean master is also do minor tillering just before bracing by bending, moving and correcting the curvature with his hands, feet and knees while the bow still warm. (bows from the bow case have to be warmed before bracing)

[jessepeltan]

You can still side tiller the bow.  I would the bow have a pyramid taper to the tips to help with tillering.  I wouldn't touch the sinew on the back, as a lot of the strength comes from the length of the fibers, and you'd be effectively shortening your top fibers, which are subject to the most stress.  I think side tillering the is the way to go on this.  When side tillering, the limb does not weaken as quickly, so it's a little bit different.  Try to get large diameter, thick walled bamboo for this project.

[JW_Halverson]

Duh, side tillering.  Why didn't I think of that, it's the obvious choice.  Huh, now I have yet another bow added to my to-do list!