Primitive Archer

Main Discussion Area => Bows => Topic started by: backgardenbowyer on September 15, 2009, 03:47:36 pm

Title: Hickory heartwood in backings?
Post by: backgardenbowyer on September 15, 2009, 03:47:36 pm

Hi there - I've recently got hold of a plank of hickory (hard to find here in the UK) which I'm cutting into edge grain backing strips.  The grain is completely straight on these - hardly a single grain line runs off the edge! The wood, however, is a mixture of white sapwood and a darker heartwood and its impossible to cut the backings without including the heartwood.

I make mostly ELBs in modest weights and the belly wood will be lemon wood, probably with something else in the core.

Is hickory heartwood OK in backings - does anyone have any experience of using backings like this?

Any advice welcome

Thanks

Stan

Title: Re: Hickory heartwood in backings?
Post by: Et_tu_brute on September 15, 2009, 04:50:50 pm

I've used backing strips which have been half heartwood (split down the centre of the bow) and they've been fine, no lifts or anything like that. These bows have been Hickory/Lemonwood ELBs, 74" and approx 60-65#@28". Good shooters, very little set.

Title: Re: Hickory heartwood in backings?
Post by: Pat B on September 15, 2009, 06:22:26 pm

You could do a simple bend test on your wood and see if there in much difference. I've used lots of hickory backing strips but none had heartwood.

Title: Re: Hickory heartwood in backings?
Post by: WillAdams on September 15, 2009, 06:32:31 pm

My 3rd and 4th bows had heartwood hickory backing strips and worked out well enough I've got two more such in the works.

Here's #4:



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Title: Re: Hickory heartwood in backings?
Post by: WillAdams on September 15, 2009, 06:33:29 pm

At full draw:


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Title: Re: Hickory heartwood in backings?
Post by: adb on September 16, 2009, 01:15:17 pm

I've used many edge grain hickory backing strips with sap/heartwood mix, and no failures.

Title: Re: Hickory heartwood in backings?
Post by: backgardenbowyer on September 16, 2009, 07:23:16 pm

Thanks for your advice everyone.  Guess it will be OK for the sort of weights I'm likely to go to.  Most of the real heavy weight longbows I've seen have backings which chase a single growth ring of hickory which would be tricky and wasteful to get out of this bias ringed plank.

btw nice tiller on your bow Will

Stan

Title: Re: Hickory heartwood in backings?
Post by: WillAdams on September 17, 2009, 06:14:04 pm

Thanks Stan!

The stave itself on that bow is a mix of heartwood and sapwood. 60" NTN, 23# @ 28"  Left-handed, it was made for my daughter.

Searching a bit, I believe a volume of TBB states hickory heartwood is stronger in tension, which was why I was using it for backing. I also like the two- tone appearance (w/ a Sapwood stave).

William

Title: Re: Hickory heartwood in backings?
Post by: backgardenbowyer on September 24, 2009, 07:58:22 pm

Found an abstract from an article on the benindg properties of hickory grown in Germany published in a technical journal on wood, they conclude:

"The intratree variation of all wood-technological parameters is quite high so that significant differences could neither be found between directions nor between heart- and sapwood."

In other words hickory has pretty similar bending properties whether its sap or heartwood and whether the grain lies flat, edge or bias, but like all wood individula pieces vary enormously.

Looks like I've got my answer and will risk these backings on my valuable lemonwood bellies!

Stan