Failure-advice needed (Success now)

[DC]

Thanks Marc That clears a few things up. I've only ever used Bamboo as a backing. I've been on the scout for some hard Maple but the two big lumber stores in town don't stock it any more. I'm going to try Windsor plywood but they don't have a big stock here. I've got enough Bamboo for two more tries so I'll be forced to look for something after that. If this one doesn't turn out well I can still cut the boo off and try again. I'm also just about out of Yew heartwood and I can't see myself cutting off perfectly good sapwood to make a backed bow. We'll see how it goes. If this shoots anywhere near 180 all bets are off.

[DC]

Pity you can't thin the Bamboo, it is too thick.

Can someone clarify something for me? TBB1 says that the outside 10% of the thickness does 50% of the work so on a .500" thick limb .050" is doing 50%. So why does it matter if the boo is a little thick? If the outside is doing all the work isn't the rest of the boo just along for the ride? Why does it matter if that part is Yew or Bamboo?

[DC]

 I ground the belly down until it was about 1/8" thick and then glued a new 3/8" belly on  it. Glued the handle back on and then retillered. I had a bit of the same problem as before. It just seemed to start losing weight very quickly in the last couple of inches. I managed to save it at 35#@27". Lighter than I wanted by a few pounds. It took a bit of set, started out at 3 1/2" reflex and finished at 2". Then I cut an inch off each recurve so it's about 1"reflex now. 64" NTN following the curve. Weighs 359 grams with an 8 strand unserved FF string. Very nice bow to shoot. I'm having trouble finding 350 grain arrows that are stiff enough. I was using a 368 grain 48#bamboo arrow with a 50 grain tip and it broke after hitting the target nock left 3 or 4 times. I found another about the same weight and spine an got a dozen or so shots recorded in about 25 shots. All the recorded shots were in the high 180's. I don't think I got one less than 183. Best of 193 but I couldn't duplicate that today while I had the camera. Success beyond my dreams. I beat my PB by about 12 fps. I really like this design Marc and I will be copying it more. I don't know if the tri lam has much to do with it. I've shot it about 100 times and don't see any chrysals yet.I'm afraid it going to die on me but I'll enjoy it while it lasts.

[DC]

Next

[DC]

I took this picture before I cut the tips off. It's raining too hard to take another

[Jim Davis]

DC,  I believe you are right about the thickness of a backing making no difference--for the reason you mention. I have put thick backings on bows and they worked just the same as thin backings on similar bows. The outside does all the work.

We'll take some flak on this--if anybody reads it.

Jim

[Badger]

  You did a great job on that one!!!  I think even Mark will be proud of you.

[DC]

DC,  I believe you are right about the thickness of a backing making no difference--for the reason you mention. I have put thick backings on bows and they worked just the same as thin backings on similar bows. The outside does all the work.

We'll take some flak on this--if anybody reads it.

Jim

I'll still try a thinner back on the next one. I thought maybe the SG of bamboo was high enough that a thinner piece may lower the mass of the limb but Bamboo ranges from .4 to .8 sg depending on species so that's a guess. I'm also wondering if it affects the sensitivity when tillering although that could be the design or just my ineptness. I'll go even slower next time, especially in the last few inches.

[DC]

  You did a great job on that one!!!  I think even Mark will be proud of you.

Thanks Steve. I was so surprised when I got that speed with a 35# bow. I think luck had a lot to do with it on this one. It's a bit of a dog's breakfast with pieces here and there and some iffy glue lines. I'll make a couple of OS bows like this and then tackle another Boo Yew. I really need some stiff light arrows though.

[Badger]

  This bow reinforces something I have been kind of preaching the last few years. Your bow has about 1 1/2" reflex which is not radical by any stretch, your performance is right there at the top levels. You indicated you backed off when it started to drop weight saving the integrity of the wood. I think this demonstrates that the condition of the wood being fresh is more important than overall reflex and aggressive profiles.

[PatM]

Bamboo can actually go over 1.0 SG if you only measure the power fiber section.

[Badger]

  Pat, tonkin cane is actually about 1 1/2 times heavier than the heaviest woods

[upstatenybowyer]

Glad to see your success with this one Don. The bend looks great and I really dig the looks of that handle!

[DC]

I sure wish I knew what I had. It's a 3 1/2" pole I got from a garden center. Like me, I guess, undetermined ancestry.

[Philipp A]

Great bow! It just shows determination pays off!