Main Discussion Area > Bows
AZ Ironwood Bow
richgibula:
So let's say that I use a thin bamboo backing, 1.25 inch wide at the handle, 64 inch length nock to nock. Is there a way to estimate thickness and tapering for a 60 lb draw for a wood this hard? Let's assume this grain lets me put in a little reflex.
richgibula:
It's hard to see the grain from a distance, so I highlighted it with a marker. I marked a proposed cut for the bow, following the grain lines where I could. I had to start a distance from the end due to knots.
The problem is that there is a transition at the arrow where I will have to cross grain lines. Since this is a board I don't know a way around that. Is there something I can do with that or should I pick a different part of the board. I like the current selection because of the reflex.
Hamish:
The limb shape you have drawn out, is the look for the bow want, but that is not how you achieve it. A bow of that shape, especially if you use a backing, is derived from the form you use to glue up your laminations. The grain where your reflex/ recurve occurs doesn't look to be anywhere as curved as the drawing, and will therefore be a weak spot.
I would use a long rule and mark a line that broadly follows the average run of the grain. From what I can see, the grain runs out of parallel from the edges of the board. Starts in the middle of the left side, and runs at an angle up to the right side. It looks to be straight enough except at each end. With a backing and perhaps a core that amount of run off will be acceptable.
I would just saw off straight boards from the new drawn line.
richgibula:
Thanks for your input, Hamish. I like your approach. The only thing I would add is that the picture is hard to see on the low resolution required by this site. So, I did a closeup of the right curvy area to show the grain direction.
willie:
can you show the ring lines marked out on the side view turned 90 degree? pick a ring about an inch and a 1/4 down from the outermost ring of the tree.
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