Grip and shelf location
A question that appears often in many of the internet bow making forums is “Where should I locate the grip and shelf on my bow?” I’m sure there are as many opinions about this as there are bowyers, so I’ll give a simple explanation of what I think is important and you can decide what is best for you. I think the two most important things that should determine the location of the grip and shelf are bow balance and shooting style…meaning whether the archer intends to shoot “split finger” or “three fingers under.”
Putting the grip in the center of the bow (from tip-to-tip) creates a balanced bow that is easy to carry on the range and in the field. Holding an unbalanced bow for even just a few minutes can seem like agonizing long hours when you are trying to stalk quietly through the brush or stand perfectly still on a tree stand. A balanced bow is easy to carry and effortless to hold. Also, when it is time to raise the bow for the shot, a balanced bow comes up smoothly and effortlessly, without conscious thought or distraction.
There can be a difference between a balanced bow to carry at brace (let’s call this “static balance”), and a balanced bow during the draw (let’s call this “dynamic balance”). The dynamic balance of the bow is mostly determined by the bow grip fulcrum and the string grip location. This is where shooting style and tiller come into the discussion. For the ease of bow making, I’ve typically just cut the grip at the center and put the shelf an inch or so above it for both split finger or three under shooters, then adjusted the tiller to balance the bow. On my designs, the tiller usually comes out pretty close to what most authors suggest (“1/8″ positive” tiller—lower limb stronger and upper limb weaker for split fingered shooters, and “even” tiller—both limbs of equal strength for three finger under shooters).
However, after building bows for awhile and doing some experimenting with test bows on my tillering tree, I’ve learned to worry less about what everyone else is teaching about tiller and to be more concerned with how my bows balance on the pivoting tree. I’ve discovered that putting the grip at bow center usually works best for three under shooting and putting the grip slightly below center works best for split finger shooting. This places the bow grip and string grip locations so they create better dynamic balance in the bow. Once the grip is cut in, I use the tillering tree to show where the limbs need to be adjusted to create static and dynamic balance. In my opinion, it really doesn’t matter what tiller measurement the bow ends up with. After all, it’s just a measurement. What really matters is that the bow is balanced. Dynamic balance means that, during the draw stroke, the limb tips pull back the same distance at every inch on the tillering tree, and during the power stroke, they return back to brace with exactly the same force. You will know the limbs are perfectly balanced when they just make a dull thump when you strum the string. The dull thump happens because the force vectors of the upper and lower limbs perfectly cancel each other out as the limbs come to a stop. If the limbs are out of balance, the forces will not cancel each other, causing vibration and making the string buzz.
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