Primitive Archer
Main Discussion Area => Bows => Topic started by: AKAPK on June 03, 2009, 09:36:42 pm
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This has been bugging me for a week,I would like to know the math for figuring max draw for a 48"NTN or any other bow 68, "70", 66 etc.... thanks for your assistance.Phillip
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A lot depends on the condition of the stave regarding knots, etc. A lot also depends on the wood species. Osage and hickory will take a lot more draw per length. Design is also a factor.A bend in the handle bow will take a longer draw. It's tough to say. I almost hurt myself falling off that fence. Generally speaking for a bow with an 8 inch handle double you draw and add 10-20 % for a nice safe length. :) Jawge
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It's possible to get a bow 2x your draw (24'' draw =48'' bow) but you'd either sinew back it or need the perfect piece of wood or go for a low weight. I never risk it since making the bow just a little longer makes it much safer and last much longer. My rule for a D bow is double the draw and add 10%. A stiff handle bow is double the draw and add 20%. So for a 25'' draw, 25 x 2 = 50'' plus 5 (10%) is 55'' D bow. 50'' plus 10'' (20%) is 60'' stiff handled bow. Your best bet is just make it a few inches longer and cut 1/2'' off of each limb till you get to the amount of set you're comfortable with. This formula is a good starting point.
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...a bow fully drawn is 9/10th broken!!! Draw length no greater than half the bow's length.
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As the others have said there is to many variables to answer that question. Design is a huge factor as is the species and specimen of wood.
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Thanks gentlemen, that about Answers that one for me :)
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If you're making it shorter, make it wider.
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Some nice tight recurves will keep the string on longer. ;D
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depends on the design. I got a 40#@30" bow wich is only 55" ntn. You can probably draw it even further, and the tiller isn't that good.
I've seen an osage shorty somewhere, wich was around 45" tall, drawing 50#@26" If I remember correctly.... and a gorgeous BBI deflexed recurve, wich was 48" ntn and drew 50#@28".
depends all on the design and tiller. If you make it bending through the handle, around 2" max, you'll probably get more than 30" out of a 56" bow. You can really get short with long drawlengths, but they'll get more set and shoot slower.
Nick
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Thats Really interesting How different woods will tolerate more draw.I notice that Osage is pretty good at that.
This 44" maple i got at 20" draw I guess thats about 5" over good idea marking the Arrows At 20 so I don't break it, never made such a dink bow that shoots good., it shoots better when Releasing soon as getting to intended draw. 2*draw length + 10% or inches = bow length wich would be about 15 draw " for a 44" Bow with recurved tips, I think that" pretty close.thanks for the Replies. Phillip
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(http://i545.photobucket.com/albums/hh367/hanshanssam/bows/ash%2055in/Afbeelding.jpg)
my 55" ash... drawn to 32" :)
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whoa Dude don't hurt yourself, that upper looks like it wants to go pop, I admire your Courage though.PK(cool Arrow)
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Working limb length is more important than overall bow length. The photo above shows a bend in the handle design that allows the entire bow to be working limb. Material also is a factor. Short composite bows like Mongol, Turkish, Asian horse bows can be drawn as much 1:1 length/draw because of the resilience of the horn and sinew.
I believe the quote above posted by Pat ( from Saxton Pope?) refers to bows made from yew. Yew is a fine bow material but has a relatively low modulus of elasticity - how far it will bend before breaking. A yew bow that will bend to 28" draw may explode violently if drawn to 29".
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I noticed the Tight re curves do help Havin a string pop off ain't no laughing matter but its not as bad as a piece of wood stuck in the noggin from a bow break.( it wasn't one I made ;D)