Violated growth rings

[Tom Dulaney]

Hello hornbowyers:


Are violated growth rings in wooden cores a problem in composite bows, the way they are in self bows? Let's say I had some limbs that needed to be de-crowned because they had an un-even back, would that be a problem? Since the bow will be backed heavily with sinew anyway, should I bother chasing the growth rings down so they're vertical?



Your thoughts/experience?





Thanks.

Tom

[EdwardS]

I don't believe the originals had chased rings.  Grooving the back and belly for horn/sinew (a la Korean bows) would violate it anyway (though they used bamboo.)

[davidjw]

I wouldn't worry about violating growth rings in a horn bow.  Typically in horn bows the outer growth rings are on the belly side of the bow, just to avoid splinters when bending the wood core to shape.  The inner rings of the tree become the back of the bow and can be violated anywhere they need to be, it's pretty difficult not to.

[Bjoern Sofeit]

Growth rings can be violated and will be violated. What you want to look at is the grain that runs along the side. Should be nice and straight. If it runs off wildly, you'll have a broken bow or a super warped piece of junk when the sinew is on.

[loon]

Growth rings can be violated and will be violated. What you want to look at is the grain that runs along the side. Should be nice and straight. If it runs off wildly, you'll have a broken bow or a super warped piece of junk when the sinew is on.

so you mean, the grain should all be parallel to the bow, and it shouldn't run off? and it doesn't matter if it runs off in the back or belly?

you're not talking about how the grain looks on the sides of the core, right, but how it looks on the back?

[Bjoern Sofeit]

Look at it like in this pic. Here the grain runs off in the end, that wouldn't be ok if it was in mid sal.

[mikekeswick]

Growth rings can be violated and will be violated. What you want to look at is the grain that runs along the side. Should be nice and straight. If it runs off wildly, you'll have a broken bow or a super warped piece of junk when the sinew is on.

so you mean, the grain should all be parallel to the bow, and it shouldn't run off? and it doesn't matter if it runs off in the back or belly?

you're not talking about how the grain looks on the sides of the core, right, but how it looks on the back?

It is simple really
Start off with perfect wood. Then make the bow.

[Tom Dulaney]

Hey guys I really appreciate the help, as always. I'm not always around so I don't get to sign in to thank you for your contributions.

Look at it like in this pic. Here the grain runs off in the end, that wouldn't be ok if it was in mid sal.

Thanks for the picture!  This only matters if it's on the back, right? You can have some runout on the belly? Open question for all, cuz I don't expect a quick answer from just one person. We gotta go to work!!!

[Bjoern Sofeit]

That's a hard question, maybe it's possible to take a pic of the grain? Ideally you'd want to avoid runoff in the belly or back. Either the core breaks, or the horn delaminates with parts of the limb. In the mid of the limb it's a complete dealbreaker, in the fades or near the grip, you might get away with it if it's a little runoff. Runoff & sinew *always* means twists.

A friend tried to cut out siyahs of a bigger maple slab for a lightwight mongol conquest bow, and although it was covered with quite a bit sinew, the whole thing unsurprisingly literally exploded.

[mikekeswick]

Iffy grain just isn't going to handle being bent into the correct shape in the first place (Turkish bow). For other styles that don't need an exaggerated steam bent core then I totally agree with Bjoern. It simply isn't worth all the time and effort to use dodgy wood. The answer is simple really go out into the woods and look for perfectly straight saplings with no flaws.
Making a hornbow and waiting 6+ moths for it to dry only for the core to break is no fun at all.

[davidjw]

Avoid pin knots as well, just found one in the sal of a core I had glued up and was preparing for horn.  Goodbye core, hello firewood...

[Aaron H]

Iffy grain just isn't going to handle being bent into the correct shape in the first place (Turkish bow). For other styles that don't need an exaggerated steam bent core then I totally agree with Bjoern. It simply isn't worth all the time and effort to use dodgy wood. The answer is simple really go out into the woods and look for perfectly straight saplings with no flaws.
Making a hornbow and waiting 6+ moths for it to dry only for the core to break is no fun at all.

Mike, why saplings in particular? 

[mikekeswick]

They are more elastic (with regards to bending the core) than a bigger tree but you use what you can find! I've planted some Tartarian maple but it is taking a while! I plan to coppice it for more young shoots when the time comes.