Author Topic: Wood Combos...  (Read 6058 times)

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Offline ajooter

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Wood Combos...
« on: December 01, 2014, 09:01:47 pm »
I have some hickory and maple backing strips, both ~1/8" thick.  Both of them will have to be spliced in the middle.  What would be a good combo for a trilam or just a backed bow?  I only have white oak right now but I can get my hands on some nice ash or hickory boards.  Thanks in advance for any input.

Aaron

Offline adb

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Re: Wood Combos...
« Reply #1 on: December 02, 2014, 11:10:08 am »
White oak, maple, ash, and hickory are all tension strong backing material if you're making lam bows. None are great in compression. Can you get your hands on some compression strong wood? Like ipe, osage, or yew heartwood?
Also, splicing backing material will greatly decrease your odds of success. It's fine for core lams or even belly lams, but not for backing strips, unless you cover the splice with a reverse grip. The backing material you choose needs to be straight grained (I use edge grain) and one continuous piece, so the wood fibers can stretch together in tension.

Offline Knoll

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Re: Wood Combos...
« Reply #2 on: December 02, 2014, 11:47:31 am »
... The backing material you choose needs to be straight grained (I use edge grain) and one continuous piece, ....
Are you buying 6/4 and 8/4 and ripping off the edges?
... alone in distant woods or fields, in unpretending sproutlands or pastures tracked by rabbits, even in a bleak and, to most, cheerless day .... .  I suppose that this value, in my case, is equivalent to what others get by churchgoing & prayer.  Hank Thoreau, 1857

Offline ajooter

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Re: Wood Combos...
« Reply #3 on: December 02, 2014, 01:38:15 pm »
Adam,
I planned on covering the splice with a lam.  Maybe even doweling down the center and then covering those with a thinner lam.  I may be able to get my hands on some ipe.  How critical is the grain orientation on the ipe being the belly wood?

Offline Springbuck

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Re: Wood Combos...
« Reply #4 on: December 02, 2014, 06:30:20 pm »
 My experience is a little different from adb's.

   If I have a stiff handle and the backing strips extend way inboard of the fades, and I have a good glue line, I have had no trouble with backings lifting on the front.  I have even not had them actually meet before, but that area where the backing strip runs out better not flex AT ALL, and several inches under the backing must be stiff, too.  It helps to "v" splice or slash splice rather than just butt or skive splice, if they do reach, or the handle is short.

So, I agree that getting compression strong wood like osage or ipe is a great idea, but if you think about it, any of those woods you have can be made into a self bow, and all are tension strong woods that can be used for backing.  I think you have a lot of cool stuff you could try.  I'm assuming you are asking because you have boards available, right?

So, you are gonna make laminated board staves!  No compression strong woods?  Pre-heat treat a hickory belly, both sides, good and strong, glue up to a good backing, and trap the limbs a bit.  That should be a good combo. 

 Backed bows fail/break/take set for the same reasons selfbows do.   A sawn hickory backing probably isn't any stronget than an intact elm or ash growth ring.   Backed or not, they should hold nicely with the right design.  Now would be a good time to try taking advantage of some Perry reflex, since it relieves belly strain some.  Make up some backed, wide pyramids.    Also, the tri-lam could be Baker's vision of backing and core glued up in exaggerated reflex, then pulled into reasonable reflex and the belly applied.

  The only thing I wouldn't do is a white oak belly.  White oak just seems to want to take set.  Heat treated it still takes set like a wood even lighter than itself.

Offline adb

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Re: Wood Combos...
« Reply #5 on: December 02, 2014, 07:06:09 pm »
... The backing material you choose needs to be straight grained (I use edge grain) and one continuous piece, ....
Are you buying 6/4 and 8/4 and ripping off the edges?

Yes

Offline adb

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Re: Wood Combos...
« Reply #6 on: December 02, 2014, 07:13:19 pm »
Adam,
I planned on covering the splice with a lam.  Maybe even doweling down the center and then covering those with a thinner lam.  I may be able to get my hands on some ipe.  How critical is the grain orientation on the ipe being the belly wood?

Forget the dowel. It won't help. A good glue joint is plenty strong.

Ipe is great belly wood. Grain orientation is not as important as backing wood, but I still look for good straight grain. It just makes your life easier down the road. I've had a bit of bad luck with knots developing cracks with ipe. Not chrysalis, but definitely cracks.
When it comes to board bows, it's always in your best interest to look for straight grained wood with no knots. Staves, not so much.

Offline ajooter

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Re: Wood Combos...
« Reply #7 on: December 02, 2014, 07:50:47 pm »
Kind of an off question...I usually ruff all my bows out with a hatchet.  Never done it with a lam bow tho.  Should it make a difference as long as the glue joint is good?  I have a little benchtop bandsaw but I've done more harm then good with it.

Offline adb

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Re: Wood Combos...
« Reply #8 on: December 02, 2014, 10:53:52 pm »
No idea. Never done that, so I don't know. I profile all my bows with a bandsaw. Why are you having trouble with your band saw? Not set up properly? Wrong blade?

Offline DavidV

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Re: Wood Combos...
« Reply #9 on: December 02, 2014, 11:09:12 pm »
Kind of an off question...I usually ruff all my bows out with a hatchet.  Never done it with a lam bow tho.  Should it make a difference as long as the glue joint is good?  I have a little benchtop bandsaw but I've done more harm then good with it.

Hatchet would work fine. Planes would probably be faster if you have them
Springfield, MO

Offline DarkSoul

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Re: Wood Combos...
« Reply #10 on: December 03, 2014, 09:12:03 am »
Do not use a hatchet or drawknife when roughing out laminated blanks or boards. A plane works ten times better and safer.
"Sonuit contento nervus ab arcu."
Ovid, Metamorphoses VI-286

Offline eponym

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Re: Wood Combos...
« Reply #11 on: December 03, 2014, 11:02:04 am »
I have some hickory and maple backing strips, both ~1/8" thick.  Both of them will have to be spliced in the middle.  What would be a good combo for a trilam or just a backed bow?  I only have white oak right now but I can get my hands on some nice ash or hickory boards.  Thanks in advance for any input.

I find this page useful.

http://www.yewtreearchery.co.uk/woods.htm

Offline ajooter

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Re: Wood Combos...
« Reply #12 on: December 04, 2014, 04:00:43 pm »
Thanks for the advice guys...hopefully have some bows to post soon.