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AZ Ironwood Bow
willie:
on the side of the beam you have marked out rays, which in the case of your wood, are much more apparent, but they dont tell much about the direction of the grain.
http://www.primitivearcher.com/smf/index.php/topic,68359.0.html might be helpful.
the ringlines in your beam are quite fine and may be very difficult to follow. As noted in the topic linked above, the bowyers bible has a good explanation and some drawings also .
if your bow stave has much run out, which I think might be the case, it is at risk of breaking. this is why I suggested considering just a belly lam of mesquite. If the best part of the bow has straight grain, and is of a known bow wood like perhaps hickory, your chances of the bow holding together are much improved. If your mesquite is harder than the hickory you may realize a gain in performance for having it on the belly face. alternately you might be able to make a slightly higher poundage bow compared to a similarly sized all hickory bow, or a slightly smaller bow of the same poundage.
richgibula:
The rays are longitudinal, the grain lines are the ones I marked with the black marker. They intersect with the longitudinal grain lines on the top side in the end image.
I don't intend to shave this wood with a draw knife. My arms would fall off. I hope to orient the bandsaw cuts in the best direction possible and use a backing. The other questions that remain are the width and thickness of the bow arms compared to a softer wood. Should this be thinner, narrower, wider than hickory?
willie:
rich,
Sometimes terms about wood characteristics are confusing as different trades and usages speak of some things interchangeably. For me, ring lines represent the annual growth rings on a tree. your beam has very thin growth rings and you can see hundreds of years of growth rings in the end view. I guess a furniture maker would call this a fine grained piece of wood, but grain means something a little different to the bow builder.
Each years growth consists of long thin cells or fibers. We, as bow builders, would like to have a stave where the fibers grow straight up and down the tree, but sometimes the fiber orientation is wavy as it goes up the tree or the fibers are laid down with some spiraling. the run of these fibers is what we call the grain these fibers are continuous only in a single years growth.
when working with a sawed log, we have to try to do whatever we can to not cut across the fibers when roughing out a bow. as we cannot actually see the fibers we can only make a best educated guess as to how they lie in the board. violated ring line are one of our best indicators. your russian olive photo shows many violated rings, as it is easy to see in coarse ringed wood especially in the flat sawn condition. rings seen in a rift or quarter sawn cut take more care to visualize the run of the grain.
I highly suggest reading the traditional bowyer bible check out page 19 in both volume 1 and volume 2
https://shop.primitivearcher.com/product-category/books/?product_orderby=default
richgibula:
Thanks for your help. I read this book, or at least selections. I don't know how closely I can keep within a grain line with a bandsaw, particularly when avoiding knots, having grains at an angle to the surface and having wavy grain lines.
Having said that, I am still wondering about how thick and wide to make a bow out of wood like this.
willie:
your cuts should follow the grain and flow around knots, the stave becoming wider in those areas
not knowing your bow design or length, proposing dimensions is hard to guess
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