4) I suggest you use all the same size bamboo. (all the same thickness) This way it will be easier to tie/tape together and you wont have to worry about having some weird deformed shape at the grip area. As for length, If you use 4 pieces make the first piece the same size as you are tall. the next piece 8-12" shorter than the first. Your third piece should be about 16-20" shorter and the last just make it about 16". (This is just off the top of my head) so, if you are 6 foot, the first piece would be 72", then 60-64", then 40-48" then 16". Make sure when you tie them together you have it staked so that the longest piece faces you, then the next longest and so on.
If you want to add more weight, just add pieces that are in between those measurements, not the same length. Or, you could shorten the pieces. It depends how far you pull the bow as well. For 28" you only need a bow of 68" at most.
5)Taper means to reduce gradually or become smaller or thinner toward one end. This can be done by scraping,shaving or whatever with a knife,axe or other bladed tools. Of course you could also use a rasp or file to do so, but I think it would be easy for you to obtain a knife than a rasp? Basically, you want the area close to the handle to be thicker and wider than the tip, which should be smaller in both width and thickness.
As for the Bhutanese bow, I have no links. However, I can give you a pretty good set of dimensions and tips to make it.
First you will need a few things.
-tape or cord
-knife/rasp/machete/axe you get the idea...
-36" pole of bamboo with walls 3/8-1/2" thick or two separate slates of that thickness/length and a width of 1 1/2"
-bow string (you can use anything that wont stretch much)
-heat source (this can be a stove/ bed of coals/ heat gun etc)
-sand paper
Ok, if you get the bamboo in pole form, you must now split it into 1 1/2" wide slates. If you got them in slate form, dont do anything yet. Next step is to draw out the taper. (basically the shape of the bow arms) from the THICK end mark out 1 1/2" wide and at the other end mark out 1/2". Make sure these two measurements are centered! Now remove all the material outside the lines you have drawn. You should now have a isosceles trapezoid shaped limb.
The back of the bow (part that faces away from you when you hold the bow) should be the non glossy side of the bamboo. Make sure you DONT cut this area in anyway. sand the edges round and smooth as possible so that you can run a cloth over it and it wont catch on anything. After you have dont this to both limbs, but out the tips (nocks in bowmaking terms) It should look like in the picture I will show below) Make sure these are smooth with no sharp edges that could damage your bow string.
The next step is optional, but it improves performance a lot. The glossy side of the bamboo is the belly. Take your heat source and slowly and carefully heat the GLOSSY side of the bamboo. Do this slowly for about 30 minutes to each limb until it is golden brown, not black. This increases the bamboo's strength and will make a faster/stronger bow per pound. After both limbs have been heat treated, tape or bind them together at the thick end. Make sure they both have the same side up. (non glossy side) They should over lap about 8". You can put a very small nail in the middle, but Make sure it is very thin so you dont split the bamboo. This helps prevent slippage but it isnt needed to create a working bow if the bindings are tight enough.
Once everything it assembled, make a string with one loop at the end. The string should be as long as the bow. Tie one end to the bottom tip so that the string is about 4" shorter than the bow. Make sure that you bend the bow so the glossy side is the INSIDE of the curve and the dull side is the OUTSIDE of the curve. Bend the bow and slide the loop onto the top tip notch.
Alex
