Hickory Problems

[KLittle]

Hey folks,

I had an old bow (7 years) give up on me a few weeks ago, rebacked it with hickory (cut with the grain) to have it blow a week later, I could write that one off as rebacking a well shot in bow was always a bit iffy..

Then made another longbow (ipe/hickory) 40#@28", 70" NTN, full compass tiller, hickory cut with the grain. It's had in the region of 500 arrows through it no problem, but has now failed the same way as the other hickory backing (albeit less dramatically), mid limb, as shown in the pictures.

I'm thinking to try cutting the hickory so that the grain of the backing is at 90° to the glue line next time to try and give it less of a reason to start lifting.

What do we think? Am I having terrible luck with my backings or am I doing something wrong?

Many thanks, Kieran

[willie]

were both the failures from the same hickory source?

[KLittle]

Hi,

Yes, both cut from the same board, all but identical strips

[PEARL DRUMS]

Do you have any way to get to find the end scraps? Id like to see the end grain on your hickory. That being said, see how the source end break is flat and not jagged or split? Makes me wonder if its healthy wood.

[KLittle]

Hey Pearl Drums, afraid I dont have any of the end scraps but I've got a shot of the end of the board both were sawn from?
What sort of things are you considering by unhealthy?

Many thanks for your help 


The grain runs clean down the length of the board on the sides.

[PEARL DRUMS]

Generally speaking when a splinter lifts you have run off which creates a pointy shard. Your break is straight across. That sometimes means the wood may have died from infestation. Id suggest cutting backers of the sides of that gem, basically your thickness is now your width and looks 1/4 sawn.

[KLittle]

Thanks very much, I'll have a try cutting a backing as if it was quarter sawn and see how it behaves..

[KLittle]

Had a go at binding the crack closed.

First flooded with cyanoacrylate and clamped, then wrapped in epoxy soaked linen, more epoxy massaged on top and heated to improve its penetration.

I'll tiller it out and see how it shoots later in the week.

[PatM]

If there really is inherent weakness in the wood you'll just chase it around the limbs by wrapping each break.

[kleinpm]

If there really is inherent weakness in the wood you'll just chase it around the limbs by wrapping each break.

That is what I was thinking. IMO, bows are to much work to use materials that have a history of failing.

Patrick

[KLittle]

I'm hoping that its a specific fault line in the wood seeing as how two lams have broken in the same place, rather than an overall bad piece of timber. We shall see

I've never tried wrapping a fault before so this is a practice at that at least..

Hey, if the bow works, thats a win, if it fails again, its firewood!

[kleinpm]

I didn't mean to imply that I wouldn't attempt to salvage the bow. Your right - it could be fine except that one spot.

Patrick

[blackhawk]

I'd do a bend test with that particular piece of lumber before using it again..in fact if it was me I wouldn't use it for backing anymore bows no matter what sawn configuration

[Zradix]

I have had the exact looking type of break in hickory before.
Is the hickory in the pic stained or sealed at all?
The hickory I had fail was my 1st experience with hickory I didn't know what it was supposed to look or feel like.
The hickory in your pic looks just like the bad hickory I had.
It had a little darker tan color. The grain was a little deeper and wider than it should be. Also, when you looked really close at it you could see what looked like little "cells" in the grain furrows. AND..when you cut or sanded it the dust felt quite granular...like very fine sand...not like "soft" saw dust.