Hello,
After posting my last bow, a few folks have been asking about cherry bark and I thought I would share some recent findings of my own.
First off, you can find a "Build A Long" with this link:
http://www.primitivearcher.com/smf/index.php/topic,2366.0.html I posted this almost 2 years ago and I really have not changed any technique.
OK now for some of the more recent findings:
1. Once the bark is harvested, if it's laid out flat and in a dry place, like a garage, it should EASILY be dry within 3-5 days. If the conditions were right, I'd start using the stuff after 2 days.
2. When ready to apply the bark, I like to soak the strips in lukewarm water for somewhere between 2-10 minutes. The time duration depends on the thickness and pliability of the material. The warm water will soften the bark up and make it conform to the limbs back a lot easier as opposed to using hard, semi flexible piece of bark.
3. Another bonus about having a moist strip of bark is that it gives you a little more time to apply the barking strips without having to worry about the glue drying out. I'm no "glue expert", but initially when I used "bone dry" bark, the bark tended to soak up the glue faster than normal and it almost seemed to be too dry when I was finally sealing it up. When the strips are moistened, the glue seems to stay "wetter" longer, which definitely helps out the application process.
Performance Boost Observations:
On my latest bow, ("The Drop Tine Bow"), the weight of the bow was ~52# @ 25" prior to applying the bark. After applying the bark, the weight was ~57# @ 25"; an increase in bow weight by 5#!
Now I know that may be a crazy statement to make, but I stand behind my finding. There are however, I believe there are some very specific circumstances behind the design of bow that really benefit from the cherry bark. Secondly, I never measured the arrow speed before and after the application of the bark. And since CAST is not measured by "bow weight", the benefit of the increased bow weight is inconclusive.
Additionally, I cannot prove the CAST performance is better because I do not know if the additional draw weight I created "out-benefited" the additional limb mass I added because of the cherry bark, even though the cherry bark increased the bow's weight by 5#.
Here's why I think the bow's weight increased by ~5#:
1. The design of the bow is a very efficient one. Its dimensions are 57.5" tip to tip and it's a "Bend through the handle" bow. When you pull this bow back to my draw, 26", you can tell that every inch of the bow is being taxed. If you look at the attached picture, the ellipse follows the profile of the belly. I purposely show a gap so you can see how the bow really has no "flat spots" in it, and that it's really bending all the way through the entire bow. I believe this is the main reason why the cherry bark had such an impact on increasing the bow's weight. Although I have never sinew backed a bow before, I believe the same principles apply; only use sinew on shorter length bows where you have a higher % of working limbs.
2. I used full length cherry bark strips. I say this with one exception; the lower limb has a 2nd piece for the last ~5" at the tip, where the least amount of flexing is happening. And when I say full length, I mean strips that are as long as each bow limb. NOT the entire length of the bow; that's one huge cherry tree!
My thought is that by using full length strips, you get the advantage of stretching a single piece of bark and really pushing its limits. If you were to use two pieces of bark per limb, it's obvious you now have a “break” in the limb and you're not stretching the bark as hard as you could be with just a single piece.
So please bear in mind, these are just my findings and musings and I'm sure others out there have even better information about using cherry bark. I welcome anyone else to post their thoughts and findings as well; we're all here to learn and grow together!
I plan on making another Hazelnut bendy handled cherry bark backed bow, and I promise you this time...I'll have much more data to either backup, or squash the performance boost benefits.
Cheers, Joe
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