Limb length....

[AKmud]

So in the TBB volume 1 I noticed in the section on design the author mentions making the top limb 1" longer than the bottom limb....  Is this in regards to having a positive tiller or what?  I'm not fully understanding the reasoning behind an off center bow.  

So far I have built my bows with equal limbs and they don't seem to have any problems with tuning or accuracy.  What is the advantage?

I should mention that I have only built stiff handle bows to this point with the center of the bow being close to the web of my thumb on the grip.

[Art B]

Here's a discussion I had with a AKDan a while back about that subject. Hope it helps.  http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=002170     ART

[AKmud]

Thanks Art, I read through your interpretation and am realizing I have a LOT to learn!  

Other than stressing the lower limb, are there performance or tuning issues that will be encountered if the bow is "off center" the wrong way and inch or two?  So far my layouts have been stiff handles using even limb length with the center of the bow falling right between the shelf/rest and the web area of my grip.  I typically have been using a flat grip which would fall under your description of "low wrist"?  

Should the bow center be more into my grip or am I ok?

[AkDan]

a hill grip would be considered a low wrist, where an asbell grip would be considered a high wrist or straight wrist.  Most bows fall under a medium wrist grip.

[AkDan]

Hey Mud, I got a copy of something you may want if you have a table saw?!?!  Doesnt need to be to fancy, you'll need to make a relatively simple (well explained) jig for it.  

Drop me a line if you're interested.  

Dan
[email protected] or [email protected]

[AKmud]

Email sent!  Thanks!

[Art B]

AKmud, I think the vast majority of us who shoots a long bow do so using a medium to flat/low wrist grip. That requires an arrow pass of between 1 1/2" to 2" above the dimensional center of the bow. If you're placing your arrow pass/shelf at the center of your bow and gripping below that then you're basically shorting your lower limb by a considerable amount even with same length limbs.

Think in terms of your limbs beginning at dimensional center of your bow without a handle (handle is added for comfort only). Concept here is to grip your bow close to center as you can to apply the same amount of pressure to each limb as you draw your bow. NO MATTER HOW YOU GRIP THE BOW! And of course, arrow pass/shelf is then placed above the bow hand.

Another advantage to equally straining your limbs using the correct grip is equal limb mass distribution. Makes for a much smoother shooting bow with less hand shock.  

Yes, you probably can equally distribute limb strain by the way you now lay out your bow but you can not equally distribute limb mass. That's if your lay-out is as you described and I'm interpreting things correctly. ART

[Roy from Pa]

Art, isn't it also true, that if one of your limbs is stronger that the other, as in being bent more than the other, the arrow will fly up or down towards the stronger limb?

[Art B]

If you draw your bow, and instead of feeling even strain on each limb, you'll noticed arrow trajectory will suffer Roy. Esepcially if the lower limb weakens. I've noticed if the bow's positive tiller degrades it'll be hard to keep arrow trajectory up.  

It's not a big concern if positive tiller increases. The bow may become a bit shockier because of timing problems IMO.