Limb length design

[Roy]

Bout time you get yer butt out of bed ole boy:)  Afternoon Art..

It scares me to death just thinking about drawing  a bow back by hand a few times to reach your draw length like you have told me you do. I'm sure with a pre tapered limb thickness and width, the bow does/will have a good natural tiller bend. And that's how your and my bows are built from the start. But what about any differences that might lie inside the two different limbs, as in bottom of tree to top of tree stave? I will say I've been laying out my bows like you explained it to me a few years ago and I'm pleased with the bows I'm turning out. But I work the crap out of them on the tree, and you don't? However, I shoot three under and that in it's self makes tillering a bow a lot simpler due to the fact you are pulling closer to the center of the bow and attaining almost equal limb strain. I have played around changing the pull rope position on my tree from split finger to three under to check the difference it makes on limb movement, and three under sure evens it up a lot more than split finger. I know Jeff makes his bottom limb about 1.5 inches shorter than the top limb, I don't. So his tree theory/setup works better for his bow design. I may go that shorter bottom limb theory in the future though, maybe not. Maybe some day when I get up the courage, I'll just string one up to a 6 inch brace height from the start and start pulling her back by hand. I'm retiring the end of this month, guess I'll have to make a road trip down there to WV and make some bows with ya ole timer.

I think threads like this are good medicine, it's a civil discussion about how we all go about building bows. Hopefully we all can learn from one another.

[Weylin]

I'm learning a lot, keep it going!

[artcher1]

Since you're retiring soon Ol' Man, maybe you can now pay closer attention !

Hey, you start with reasonably (quality) bow wood, apply a nice taper, so what could go wrong? Limb can't hinge, and you can tug on the limbs until they break. But that'll take a bit of tugging.

Now for different working properties/strengths, why I reckon carrying the same amount of mass in each limb will help there. Try this Roy: mark the center of your bow. As you're tillering, make sure your bow balances on your center mark. That'll keep your limb mass equal. Then you'll start to understand why the old timers preferred matching sister billets for their bows.

Say you "build a bow as it stands in the tree", and maintain equal limb mass as your building it. Here's what you're gone to see. Top limb a bit thicker and wider than the bottom, or bottom limb a bit narrower and thinner than the top. Do the same thing with matching sister billets and you have a more aesthetic pleasing bow. Easier to work with matching limb properties, at least for me.

If this make any sense to you Roy, I don't believe a bow should be pulled the first time until everything possible is done to insure minimal damage to the wood's fibers. Only way I can see to do that is to pre-taper the limbs instead of tapering/pulling as you go.

Something else I was going to mention. But heck, you know how that works at our age !

[Roy]

Something else I was going to mention. But heck, you know how that works at our age !
So your telling me ya forgot what ya was gonna say?

LOL I understand EXACTLY about forgetten chit:)

So by limb mass, your referring to weight I take it? So for that to work would require equal length limbs. Well not really I guess, more like you explained above.

[artcher1]

Limb length design, that's what I was trying to remember Roy !

Funny, but I never think of limbs as being different lengths. I think in terms of off-set handle, or amount of off-set for the different type grips (straight/high, medium to low wrist). And that's really what's involved with different length limbs. But you'll still see plenty of folks using a low wrist grip with an off-set handle or a straight wrist with a centered handle. You'll end up pull your hair out trying to explain this stuff only to have someone who's made one or two bows come along and say none of this stuff matters, and just shoot from the center of the bow .........Art B

[Dances with squirrels]

I too spend a great deal of time establishing an accurate taper in both width and thickness prior to ever bending the bow by any means or by any amount whatsoever. Doesn’t matter if it’s bamboo backed osage bow, an ELB, or the most character laden osage selfbow (they’re actually the most fun for me, and the tapering is a BIG part of success with them). I often wondered if I was spending TOO much time doing it, because I’d see other guys just grab a big ol’ Farrier’s rasp and rip ‘n tear. But I think it pays off to spend as much time as it takes to get it as good as possible before any ‘action’ takes place.

[Dances with squirrels]

Art, you asked about tillering bows for other grips, hi, low, etc. I have a handful of these inserts that drop down securely into my tillering tree cradle. I've got a couple more around here somewhere, but couldn't locate them just now... shop's a little 'disturbed' 

Anyhow, even though I built my cradle to accomodate the shape of handle I prefer, I'll drop the flat one or convex one in there on occasion, after the bow has at least made it to brace so it'll sit there, to make it easier for the bow to pivot if it so wishes, and let me know even better if I've got the thing timed/balanced. It's kinda like fine-tuning the thing, cuz if one limb is just a little stronger than the other, it's gonna be easy to see.

For balancing the limbs for someone who shoots high or low pressure on the grip, which one I'd use would depend on their handle shape and where they put the most pressure. Even if I had to make a new one to accomodate them, it only takes a couple minutes. Since they just drop in, they can be switched in split second if I want to find a better-suited one, or compare or check something or whatever. The insert that is high on one side can be flipped around for high or low pressure on the handle, and used on some locator grips.

[Dances with squirrels]

Here are the pulleys down below. Which one is used depends on split-finger or 3 under, and whether the top limb is on the left or right. They're each secured by a single set screw, so they can be loosened and moved anywere they're needed.

[artcher1]

Nice set-up you have there Jeff. Yep, that's about all the different heads one would need.

No, I don't think you can spend too much time up front with these selfbows. For example, I've applied my taper, kepting an eye on equal limb mass as I go, and have had a number of bows come out perfectly tillered when first strung. Many others only needing a few scraps to even up the tiller. Then limb weight reduction from there as needed.  Dang near impossible to miss weight when the bow is constantly in the hand and not on the tree.

 

[Roy]

Very cool, Jeff.