Primitive Archer
Main Discussion Area => Bows => Topic started by: Mesophilic on March 06, 2018, 12:08:52 pm
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I've been trying to find an answer to this question and keep getring mixed results.
In a stiff handle sinew backed bow, which matters most, the overall length, NTN? Or the working limb length?
I've read alot of bow theory, and rules of thumb like 2x the draw length plus a %. And also read that with sinew backing you can safely shorten the limbs.
But...to keep it easy, let's use 28" draw. With a stiff handle, say 4 inches of handle and 4 inches of fades and 28 inch working limbs @ 64 inches overall perform roughly the same as a 56 inch bendy handle? (minus the stiff handle and fades)
Or would the same stiff handle bow be betrer suited to the same overall length as the 56 inch bendy handle? Even though this means only 24 inches of working limb on each side of the bow? If so, is it safe to drop the working limb length that short, even with sinew?
I'm sure opinions will differ, but I trust you guys much more than the random opinions I have managed find via google.
Maybe an easier way to do this would be to ask, what overall length would you use for a 28" draw, stiff handle sinew backed flatbow in osage? And would this change if you added aome reflex to the tips?
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Both. Some guys will make a bow a bit longer than they need for a sinew job, but shorten the working limbs up and only adding sinew to that section. The sinew backed bows I have made were all "short" to challenge the sinew and I added sinew from tip to tip.
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Okay, here's the big disclaimer. THIS IS WHAT WORKS FOR ME. Others may agree/disagree and that's okay.
Considering the 28" draw you described on a 4" stiff handle with 4" of fades - Doubling 28 + the 8-inches of non-working fades = 64". This to me is the shortest stiff handled bow I would make to achieve a 28" draw. Of course, the tiller has to be close to flawless; leaving no "wiggle" room at 64". That is for a NON-sinew backed bow.
For the same draw (28) in a bendy handle design, I simply double the 28" equaling then 56" as the shortest bow I would make to achieve a 28" draw. Again, this is for a NON-sinew backed bow.
When I build a bow that will be sinew backed, and if it is to have a non-working (stiff) handle section, I'd eliminate the 4 + 4 = 8 inches from the equation. In other words, a 56" stiff handled bow will draw 28" if it is sinew backed, properly. Unless I am experimenting or challenging myself or the wood, I would consider 56" as the shortest I would make the bow considering a 28-inch draw length. For a bendy handle bow that is sinew backed I use 52" as my shortest.
For both the sinew backed bows, keep in mind that the string angle at full draw can be close to or exceeding 90 degrees. Beyond 90 degrees, I fear the string loop(s) slipping off the nocks and causing a catastrophic event. To help with this, I always flip the tips a bit to compensate.
I'm also speaking of my experience with sinew backing osage as the bow wood. I don't waste much of my time with other wood species except maybe yew.
Shortest, isn't always best. The shorter the bow, the more stress on the limbs. Fun yes, but expect to develop string follow and/or a shorter life expectancy.
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For a hunting bow I don't like anything under about 64" they are more finicky to shoot. The longer bow also has better geometry and stores a bit more energy. If you recurve the bow and sinew it I might drop down to no less than about 58". I have made a lot of sinew backed bows from 48" to 56" and tillered to 28" but they are a bit overstressed and just don't shoot as well for me.
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Ditto what Steve said.
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I agree with Badger on this, I am hunting with a 60",, bow but I only draw 25 inches,, I like to shoot all bows, but it takes a bit more practice with the bow the shorter it is,,,I have killed deer with shorter bows, but had time to practice alot,,
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Thanks guys, you've helped me alot. I appreciate this insight.
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Ditto again, what Steve said.