I've been working on a boo-bloodwood bow and yesterday I heard the dreaded "tink". I stopped immediately, unstrung it and walked away frustrated. After thinking about it all evening, I decided to give a tension patch a try.
The bow is 66" NtN, 7" stiff handle, 1-1/8" for 2" out of the fades, full taper to 7/16" at the tips. Target is 40#@30". I am switching to lefty so this was to be a low poundage bow for practicing and is also my first time using Bloodwood. I've done billeted bamboo backing on hickory many times and I've never had an issue, but this time, when I had the bow braced (5-1/2") and pulling to around 22", I was flexing it in after a stock removal and heard that noise we all loathe.
After giving it some consideration and a thorough inspection, I believe the culprit for the noise is at the stiff handle.
I think the "tink" was the butt joint popping in tension. In an attempt to salvage this bow, I've decided to attempt a tension patch. Normally I wouldn't consider this and certainly not if was on the working limb, but on the stiff handle it may work.
Luckily, I have plenty of bamboo scraps and I think something very strong in tension is required. I also think a large tension transfer area is required so that the internal shearing stresses of the glue joint will spread out. Finally, the final outer surface needs to be a reasonable distance abouve the original surface to help reduce both the final surface tension and the shear forces on the glue joint. We'll see if this works.
So what I did was use my curved scaper to create a curved glue surface on the bottom of a bamboo scrap.
So with the ends tapered into the fades and the curve tightly matched, a bit of TB3 and some clamps, I just have to wait. I'll give this at least 3 days of cure before I put tension on it.
All glued and approved by my QC inspector.
In the meantime, I'll just have to begin another first (for me) a Boo-IPE with a maple powerlam.
I'll post the results of this experiment.
