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AZ Ironwood Bow
willie:
I am not sure what you consider the proper grain orientation, but I dont think flat sawn is particularly called for with a belly lamination. In fact if there any waviness in the ring lines such that the belly lam were to have any runouot when viewed from the side of the bow. I would think a rift sawn or quarter sawn lam would be better for the belly.
would it be possible to get a few better pics of the log such that any proposed cuts could be explained better. I suppose knowing which tools you are going to cut the beam with would be useful for those wishing to advise
have you considered a carbide tooth band saw blade? expensive tooling for sure, but sometimes the costs are justified when the right project comes along.
as far as bow designs go,
a longer narrower bow might be easier if its going to be difficult to get clear pieces for a belly lam. two shorter lams could be butt jointed under the handle making the length needs fall to 32"-- 36 "
this forum member posted quite a few construction detail photos on elb type lam bows which are still on the server.
http://www.primitivearcher.com/smf/index.php?action=profile;u=534;area=showposts;sa=attach;sort=posted;start=0
richgibula:
Its hard to see on a photo but the piece is about 3 X 5 inches X 4 feet. The grain appears flat on the narrow side, facing left, and cross cut on the wider side, facing right. There are several splits and cracks. The 3 inch wide side (facing left) would be the belly or the back.
I have made bows that needed to be spliced at the handle in the past. The question is what should the geometry be in a situation where the wood is really hard and heavy. Some people have said that the bow should be thinner or narrower than if the wood was softer. This is the info I need. This wood is so dense that I have trouble lifting this piece to carry it in the garage.
willie:
--- Quote --- The grain appears flat on the narrow side, facing left,
--- End quote ---
I think I can see islands and flame tips in the rings on the sawn side (left) which would indicate the runout condition to avoid. just guessing as I cannot see well the ring lines on the right smooth side, but you would want to trace a ring line from top to bottom there and see if it is parallel to the front of the log or the sawn face on the back? (left)
were you to cut a lam from the smooth side, you could skew the orientation of 2 half length lams in the bow such that the ring lines ran closer to straight more full length pics showing each side plus an end view would help and allow someone to photoshop a recommendation.
not sure which geometry you are asking about, but any particular wood will only bend so much before being damaged or taking set, some species more than others. How much being primarily dependent on thickness. if the wood is denser, it will make for a higher poundage bow compared to the same width/thickness section from a less dense wood.
Hamish:
If the wood is 3" wide x 5" high, I would rip 3" wide x 1&1/8" section (off the 5"height). Then I would rip that piece down the middle of the width into two pieces, prolly around 1&3/8" -1&1/4", after saw kerf, and careful clean up.
Not worried about the feathering of grain on the base, its fine ringed, but at a slight angle(doesn't look too severe, especially when backed). Willie's suggestion is a good idea, so you can check how much runoff it actually has, and adjust to it if necessary.
Keep note of the ends, and which face is top and bottom. Glue up like a split pair of sister billets, handle from the same end, top and bottom faces matching so you can insure liklihood of automatically having the same properties in both limbs, of the glued up bow.
richgibula:
This is very helpful. I will try to clean up the surfaces for a better view and show a pic before I do anything. I like the idea of sister staves to get a symmetrical flex.
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