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]

The grain appears flat on the narrow side, facing left,

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.

[richgibula]

As suggested, I got some more photos.  I planed out the mill marks, sanded it smooth and wet it with alcohol to bring out the grain lines.

There is one of the end-on view. Its a little out of focus, but you can see grain lines.  The narrow side view shows the flat looking grain and the rays which are longitudinal. The wide side shows the very narrow grain where it was cut more perpendicular to the flat grain, although the piece is obviously from a small tree, as you would expect from a desert Ironwood.

I hope this visualization helps to recommend an approach to cutting this beam for a bow.

[richgibula]

Narrow side

[richgibula]

Wide side:

[richgibula]

My guess is that I should cut off a piece from the narrow side, which is 3 inches wide and cut that in half longitudinally for two 1.5 inch bow arms that I would join at the grip.

The next question is how long and how thick to make the arms given the hardness and rigidity of the wood. Should the bow be thinner and shorter than typical for the draw weight?  If I start out too large, then I waste ironwood. If I start out too thin, you can't make it thicker.

[willie]

As suggested, I got some more photos.  I planed out the mill marks, sanded it smooth and wet it with alcohol to bring out the grain lines.

There is one of the end-on view. Its a little out of focus, but you can see grain lines.  The narrow side view shows the flat looking grain and the rays which are longitudinal. The wide side shows the very narrow grain where it was cut more perpendicular to the flat grain, although the piece is obviously from a small tree, as you would expect from a desert Ironwood.

I hope this visualization helps to recommend an approach to cutting this beam for a bow.

the end view is informative.   cool looking wood btw.  which side, in the end view shot,  is the one facing the viewer in the pic with the white truck ?

one more pic would help.
would it be possible to trace a ring line with a contrasting marker, for the full length on the narrow right hand side (of the end view pic)? seeing how the ring lines run along the full length of the beam would help us advise better

[richgibula]

In the second shot, you are looking at the narrow end which is on the left side of the end view. The third shot shows it from the top of the end view.  I cannot cut the right side, looking from the end view, due to cracks and splits further up. I can really only cut the left and top sides because of those cracks, unless I cut short pieces. 

I need to first work out the cut orientation and then the thickness and length of the bow arms.

[richgibula]

On second thought, I suppose I could cut it on an 45 degree angle, judging from the bottom shot, to make the bow wood with the flattest grain facing the back of the bow.  It would maybe improve the wood function but it will waste the most wood.

[willie]

would it be possible to trace a ring line with a contrasting marker, for the full length on the narrow right hand side (of the end view pic)? seeing how the ring lines run along the full length of the beam would help us advise better

and/or also trace a ring line from end to end along the bottom face of the beam as shown in the end view.

without knowing how the ring lines run among the usable length of the pieces to be spliced, it is futile to try to advise

referring to the sketch of the boards I posted earlier. the sections you utilize should have straightest ring lines possible down the length of the board, on two adjacent sides

[richgibula]

I did the grain highlight photos. This one is the end grain.

[richgibula]

This grain highlight photo is the left side of the end grain.