patriot longbow copy

[D.E.B]

a friend of mine has a bear patriot longbow 60# @28 and i want to make myself one with clear glass over bacote veneers that will draw 53# @ 28 i made the form from an outline of his bow the limbs have black glass front and back and a center core that i belive to be carbon .030 thick and two wood lams. the limbs measure .384 at the ends of the fades and .332 9.7in. from the fades that makes a .016 taper i think? so my question for yall experts is how much do i need to reduce the stack to get a 53# bow, what size lams and glass, carbon do i need to order to make this happen ? ANY HELP WOULD BE APPRICIATED!         DUSTY

[greyhawk39]

This bow is a 64" right,and what are the veener thickness then I can give you a estimate.

[D.E.B]

yes 64 in. my materials will come from binghams the thinest i can see in their cataloge is .030

[greyhawk39]

When I built my 64" from scratch I used this formula.For a 18" riser deflex reflex longbow.

Parallel...3x .040'
Glass......2x .040'
Taper......1x .110'
At .310'I was around 55lbs @28"

Parallel...2x.050'
Glass......2x.050'
Taper......1x.110'

I don't think you will need the carbon because a longbow has stiff enough tips as it is but if you want it in your bow subtract .030' from the parallels.Binghams has a 64" hybred longbow they might have a formula that is close to the patriot they are great people that way and like to help...Jeff

[kennym]

If I figure right you have way less than .016" per inch taper.  More like .005(368247)per inch LOL  

.016" p/i on a 36" lam would be over a half inch taper in 3 feet...

Seriously tho,the taper will make a diff in stack too.

[D.E.B]

thanks for your input on my project i agree my math is not correct but i spoke with binghams today and elmont helped me figure out what i needed to use.

[greyhawk39]

To high tech for me...lmao these are the formulas that have worked, and would give dusty a starting place.You should give us your formula for this bow.

[kennym]

No offense intended guys!! I meant nothing but to say the taper rate will affect the stack.

Greyhawk,if you have proven formulas for the bow,that is the best thing!

I always encourage everyone to keep records!

[greyhawk39]

None taken input is always good...

[Jason Scott]

One thing to consider when putting carbon in a stack is that is will displace more wood than its own thickness because it is stiffer. If you are adding .030 carbon you will have to subtract more than .030 wood for the weight to come out right.

I would be lucky to get 40# with a .310 stack on a 64" r/d with 18" riser. Regardless of how much reflex there is. That is unless it is greater than 1.5" wide at the fades. I would have to go with .360 total stack for .1 glass, .370 for .09 glass and .380 if I used .08 glass. Of course that is with no carbon, just wood and glass.

[walkabout]

man you lam builders are in a league of your own, i read this and my eyes glazed over cus i cant make any sense of it at all =\\ and im actually good at math too.lol  

[Jason Scott]

Oh no, I have done very little figuring to get my stack heights for lam bows. I found a little info here and there and started saving it. I found a really good table for r/d bows that has worked well for me so far. That along with some basic rules I can get dang close weight for average spec bows. I also found a formula using cube root to make weight in order to copy an existing bow that worked very well on my first recurve last weekend. I had a Browning Explorer I 44# that I wanted to copy and make a 55 - 60# bow and the formula worked. If I had to figure all this out on my own I think I would have given up long ago and just bought prebuilt bows instead.

The real art and craftsmanship I think is in building a bow from a stave. Now that is daunting to me.

[greyhawk39]

Hey fellas, I wasn't home when I wrote down this formula and I don't want to get into a debate.
My first formula was wrong...I was off by .050" my bad.I read in my recipe book, I have for a longbow 55lbs@28'64".  

Parallel...3x 0.50'
Taper......1x .110'
Glass......2x .050'

 Sorry for the misimformation...Dusty.

[Jason Scott]

Dusty, the cube root formula I have used successfuly says that if you will make a stack of .368 at the ends of the fades where you measured .384 you may be close to 53#. This leads me to believe that the bow is not exactly 1.5" wide at the fades (maybe 1 3/8"). So make sure you get the width and riser length (all dimensions for that matter)the same as the patriot. I agree with kenny that .016 is way too much taper. You will have to remeasure and recalculate to get the right taper rate. I agree with greyhawk that it is easier to leave the carbon out because it really does not offer much at all to a hybrid longbow if it is covered with a veneer and glass. I learned this from reading the guys at WTT and I will trust their judgement. Save the carbon till a dozen bows down the road and research its benifits first. But, this formula could be off if you deviate from the exact lam makeup and dimensions of the bow you are copying. Make certain it is carbon and if it is and you get a strip that is exactly the same thickness it will skew the glass/carbon/wood ratio and there is no telling if you will be close in weight or the feel of the shot that your friends bow has because reducing the wood stack alone will throw that off.

In short, it's a guessing game the first time you build one of a particular design. Even the best top notch bowyers in the country are taking a guess when they try a new design. Then they have a bench mark and can get real close on subsequent bows from that form from then on.

If it were me I would trace the profile of the patriot and make a form. I would use this stack which does not include carbon.

glass- .040
veneer- .02
taper- .10375 @ .002
taper- .10375 @ .002
19" riser
parallel- .0625
veneer- .02
glass- .040

finished limb width at fades- 1 3/8"
finished tip width @ nocks- 7/16"

Straight side limb profile from 1.5" past fades to the tips.

I feel confident this would give me a 53# bow. It's even more of a roll of the dice if you decide to use carbon under that back veneer.

Carbon is basically a gimmick unless it is used properly. Bows that have it burried within their stack realize little if any performance gains, mostly just a slightly different sound is all and a stripe on the side. Not to mention most bowyers have experienced separation/shear issues with it because it is not homoginous with the other materials in the limb (especially next to an oily bacote veneer). Quite risky for a first attempt.

[D.E.B]

thanks jason , i will be shure to let you know what i used ond how it came out.