Yet another wood arrow question...Carbon/Wood spine equivalent

[Bud B.]

I have a GT trad shooting out of a Hill bow 55@28. The carbon is 30.5 bop with standard insert 5" shield cut feathers and a 175gr point. These are shooting well.

What would equal this in spine for a wood shaft? 50-55?

I haven't messed with Stu's calc yet and I'm estimating the shelf is about 5/16 off center.

I will likely get a spine kit for it but wondered if you experts out there may have an idea of the wood static spine I need to equal the carbon setup I have now.

Thanks.

[JimB]

You didn't give the spine of the carbon?

[snag]

Glad to help, but you didn't state what which carbons you are shooting. Also what is your draw length? Do you want to continue shooting 175gr tips?

[Bud B.]

Sorry guys, 35/55.

I've been outside trying lots of combos. And tinkering with Stu's calc It's looking like I need a dynamic spine of around 40lb.

It was hard to check today the flight as the wind was whipping around pretty good. It looked as if the 200gr points worked best. My groups were tight at 12 yards with an occasional sideways flight from the wind.

I can't really figure out the "spine is at 28 inches subtract 5# for every inch" and so on. I think my draw at my anchor with the Hill bow is shorter than my recurve. Usually it's just at 29 but I think with this bow it's 28".

If I go to a 55/75 I'm probably looking at 300+ grains up front at 30.5 BOP.

This stuff can give you a headache if you let it.

again, sorry for not posting the carbon static spine earlier.

[Fletcher]

I've had no good luck trying to convert carbon spine to wood.  I can tell you that a Hill bow will generally shoot about 5 lbs below draw weight with a 28" arrow and 125 gr point.  For each inch of arrow over 28", add 4 lbs of static spine, and 1 lb spine for each additional 7-8 grains of point weight.  Each shooter and bow is different, but that will get you very close.  With your 28" draw and a 29" arrow with a 160 gr point, I would suggest with a 60 lb spine.  A few test arrows between 55 and 65 lb will tell you right where you need to be.

[Bud B.]

Thanks Fletcher. That's kinda what I was looking for. I know it's hard to say person to person and bow to bow but I have 60-65 woodies now but I'm scared to cut'em and commit I guess.

[Bud B.]

Best I can measure in my crude manner is 7/16 off center shelf with shelf material. Does that sound about right for a Hill bow? That drops the dynamic spine recommendation to around 36-37ish.

[Fletcher]

3/16" out from center is about normal.  7/16 would be a bunch.

[Bud B.]

With bow perpendicular to the kitchen table, string up, I used a square to touch the edge of the strikeplate material. Then using a separate ruler I measured the distance from string center to the edge of the square. Dead on 7/16. Is there another way to measure that would be better? This is how I measured my other longbow's off-center cut and these two bows are the same measurement. I'm trusting the bow's back is exactly 90 degree perpendicular to the string with the limb bends.

Thanks again for your help Fletcher. I'm determined to conquer this woodie thing.

My longbows run from one inch at the widest to one and an eighth inch at the widest point on the limb. 7/16" would not leave you with much of any cutout for the arrow shelf, unless your grip area is considerably wider than the widest point of the limb, which I have never seen. What does it look like when sighting the string down the center of the bow?  5/16" is the farthest out I have seen on a Hill bow, and I cut that one down to a total 3/16" so it would shoot stiffer arrows.

[Bud B.]

I measured again using the bow back on flat surface, square to the strikeplate material where the arrow rubs it, and another ruler to get center of string to edge of square. 7/16 again. Then I took a string and taped it center of top limb to center of bottom limb to visualize center of bow at shelf area. I eyeballed the measurement from string to strikeplate material edge. Doing it that way I got 3/8 roughly.

I also got this:

 

The above GT Trad carbons fly without wobble and have produced he best flight of any arrow. The light is getting brighter.  Trying to now convert this to wood is where I get lost.

Still open for comments....  

[Stiks-n-Strings]

I have bought arrows from Rick (Fletcher) in the past and if he gives you spine advice on woodies you can bank on it. He hit my spine weight on my last set of woodies with in a few pounds. Given the right info I wouldn't hesitate at his advice.

[Bud B.]

Well, I broke out the digital calipers and the best I can tell, without strikeplate material, it's +/-3/16. With strikeplate material it's .2004 or roughly 1/5th.

Now I'm really confused. The flight of the above arrow is great.

Not sure what I was doing wrong.

[Patrick55]

Other that over complicating things, You are doing nothing wrong.  
There is no way to compare wood to carbon. YOU CANNOT CONVERT CARBON TO WOOD OR VISE VERSA. IT AIN’T GOING TO HAPPEN!
Two different species all together. Put down the calipers and forget the carbon specs and do not let if confuse you. YOU CANNOT COMPARE WOOD WITH CARBON!!!. If you want to shoot wood, go to the spine chats from way back and apply the AMO standards. Call a few Traditional Fletchers that specialize in wood and you will see what I mean. There is not one out there worth his salt that will not help you. I am as guilty as the next guy in getting too complicated with specs. It is totally unnecessary.  Remember; K.I.S.S. That is what Trad Archery should be. (But it is fun to explore LOL) YOU CANNOT CONVERT WOOD TO CARBON NOR CARBON TO WOOD!!

[Bud B.]

But if you can't get wood to fly right, and no shops nearby fletch their own wood, cyberspace is all you have. Gotta pick brains somewhere. And the calipers got me a better read on the shelf cut, so why drop'em?

For those who have posted helpful comments I appreciate it.

[JamesKerr]

I would give the people at 3rivers a call. If you give them your specs they should be able to get you extremely close to the perfect spine for your bow.

[snag]

If your bow's shelf is cut +7/16 and you want to shoot 150-160gr tips those 60/65's should work. If you are uncomfortable about cutting down your finished arrows then get a couple of "testers" at a reduced price to try out.

[Bud B.]

I have some 60-65 Doug firs uncut but finished shafts. I'll give those a try.

[Shawn Leonard]

Bud, bet ya could shoot .600 spine with that same 175 up front and get even better flight!! Try it, I am sure you will be surprised! Try 275 on the 35/55s I bet they fly even better. Sorry Stu's calculator has a lot of guys well ovespined even when figures entered correctly. I would say for wood you could shoot 60# spine cut to 30.5"s with 125 grain point, so 60-65# spine. Shawn

[Bud B.]

Guys, I appreciate the help. I REALLY want to shoot wood out of this new bow. For the last year I have done well with aluminum and carbon. The wood always gives me a fit. The learning process is frustrating to say the least but I am determined.

Again, thanks.