Bamboo bow

[JamesV]

I am building a 70" ntn all bamboo bow, core is Moso .150 tapered .002 per inch belly and back will be bamboo .200 for a .450 limb thickness. Does anyone have any thinking on this combination or the estimated poundage. I could add another lam if necessary, shooting for a 45-50 @ 28. using a 16" riser. Also the back amd belly boo will have to be sanded to remove the rind.
     
            Thanks Guys

[JamesV]

Finished the Bamboo bow. And it    was a total disaster. The poundage came out really light and after exercising the limbs it took a lot of set and developed a bad hinge, loosing another 5#. Shot it a few times and retired it to the recycle bin.

[bigcountry]

Can't you add another belly lam?  Or even take a planer and flatten the back and add another strip.  I have been thinkng some about this.

[Loren Holland]

Wow?! very interested as to what happened. i have been wanting to build an all bamboo like DutchWarBows build along for awhile now, i have two pieces picked out and was just about to buy some Marble Wood for a riser.  He used two bamboo pieces and you used 3, what went wrong?

[chrisg]

The all bamboo bows are good ones but one has to let the glue dry completely and if one draws the bow beyond the target weight, well that's all you get. I did the same with one. The core lams need to be substantial and once the round section of bamboo is out of the equation then the rules are as per flat laminated material. You seem to have only had a back and belly lam and no core lams? Even though boo has amazing recovery and smoothness you still need a core and to go slow. The Yumis and other Asiatic bows go up well over 100# and take no set so perhaps all that happened there was it was a little under engineered? Any experience building a bow is worth it if one gains a lesson from it! Get stuck in on the next one!
chrisg

[chrisg]

oops! You mentioned a core of Moso!Ok then perhaps it needed a litle more than what you had. Did the glue up go via hot box? Some folk have a power lam through the handle and out into the first portion of the limbs. Helps with speed but must taper smoothly out to almost zero and not be much longer than 1st third of limb
chrisg

[JamesV]

For this build I used 3 Moso slats 1.75" X .25' X 6' I flattened them roughly then cooked them in my heatbox 6hrs @ 200 degrees to remove the moisture. The heat box was saturated afterwards. I then finished grinding them flat. The core was run thur the planer to flatten the node side and taper to .002 per inch on both ends. The center of the core was .150 and the tips were .080. Glued it up and cooked it 4 hrs @ 180 degrees. Thinking back I did let these peices of bamboo sit in my shop almost a month before using and had to re-grind the back and belly pieces to flatten them again and remove some mildew. I cut the core the day of the build. I think now that moisture could have played a big role in the failure.

[chrisg]

Ah! You say you ground the node side? If that was a lot it could mean that the power fibres that are located near the outer surface of the boo were ground off leaving mostly pith. Then the boo will have very little resilience at all.To get the most from the outer back and belly lams one should grind only the inner pith part and leave the outer rind and nodes intact until finishing stages. To make a core it is hard to retain those fibres without cutting long narrow strips and making a composite core like in the Yumi bow. Check them out. It is possible to flatten the nodes by careful use of steam and pressure between two flat strips of board, at least I have been told this, the high parts can be scraped down a bit too. Personally, I would either make a composite out of narrow strips, retaining as much power fibre as possible or else use a maple or action bamboo lam for the core. The boo is great as an outer both back and belly.
chrisg

[JamesV]

Chrisg,

Thank you for the input, You are exactly right. Funny I had some laminated action boo I could have and should have used for the core but thought I would experiment a bit. One thing I have learned from you guys is that you will learn a lot from your mistakes. And that someone on here has already done the dumb things and is willing to share the experience and some good advice to help us new guys.

Thanks again

JamesV

[chrisg]

soo right! Glad that we could help, another day someone else will learn something too, I sure have, the gang is a great place to learn. Chrisg

[twodogs]

I'd love to try to make a Boo Bow, are there any documents that could assist a new bowyer?

Doug

[twodogs]

I'd love to try to make a Boo Bow, are there any documents that could assist a new bowyer?

Doug