Spine Question?

DawgDoc · April 01, 2013, 11:57:00 AM

I know arrow spine is a much debated topic on this site and different for everyone but I've got a question. I've been shooting carbons for a while and they always appear to be a little stiffer than what's advertised. I recently have been doing some tuning on my Bear takedown and swapped to an elevated rest on this bow because I wanted to try vanes. This takedown should be around 57-58 lbs at my 29.5" draw assuming its marked correctly. I was doing some planning with my bareshafts and wound up getting straight arrows with a Gold Tip 35/55 full length with the standard insert, 1.25" aluminum footing, and 315 gr of point weight. Does that seem like a high point weight to anybody? It seems like this would be too weak at that length and that much point weight to me? I got to questioning myself and had a buddy watch me shoot to make sure I was reaching full draw and also stand behind me while we added point weight and watched arrow flight.

danseitz · April 01, 2013, 12:33:00 PM

The account of your set up reminds me of the aeronautical report of the hummingbird. He shouldn't be able to fly, but he does. Your set up is weak. I would not feel comfortable with 315 grns of point weight, nor would I "trust" 35/55.

Shawn Leonard · April 01, 2013, 05:50:00 PM

Does seem a bit high in point weight, but what people do not realize is that a carbon recovers from paradox very quick and carbons are also designed and rated for compound bows. I know guys who shoot 50# compounds with .500 spine carbons with 200 grains of point weight or more. I do not find your results that unusual. I know guys who shoot 50# trad bows and 35/55's full length with as much as 425 grains of point weight. Shawn

April 01, 2013, 09:14:00 PM

That does sound like it "should" be too weak.

I can tell you from experience, running many dozens of carbon arrows through a spine tester, I have yet to find a single shaft that was not stiffer than what is written on it! I shoot GT 55/75 and have run a BUNCH of these through a spine tester and not a single one was .400 spine. Most are in the .360-.380 spine range.

Bisch

April 01, 2013, 09:15:00 PM

Oops, double post!

Bisch

BWD · April 01, 2013, 09:58:00 PM

That 1.25" aluminum footing is messing with you, just a little bit, too.

Ajooter · April 02, 2013, 06:25:00 AM

You said you did some bareshaft planing so I assume you shot some fletched shafts with the bare shafts? How did they group? If they arent grouping you could still have some adjustments to make. If they are keep shooting and have fun.

I just recently stepped up significantly in point weight (100 grain brass insert and a 245 point). Arrow requires very little fletching and steers in the a crosswind great!! I read troy breedingsbareshaft tuning method on the tuffhead website ( web page ). Hope some of this helps. Tuning can be a frustrating sometimes.

Fanto · April 02, 2013, 06:38:00 AM

I have found that the goldtip trads tune and fly beautifully when the AMO slide calculator and Stu Millers calculator say they should be 15-20lb underspined.

The consensus seems to be that point weight has less impact on dynamic spine that the calculators/ratios indicate.

I can shoot 3555s, 5575s and 7595s from my 60lb bow. all have different point weights (100gr apart) and the 7595s are 1/2 longer all impact the same (left and right) obviously the 700gr 7595s drop a tad more than the 400gr 3555s!

DawgDoc · April 03, 2013, 09:26:00 AM

Thanks for all the input guys - it makes me feel like I'm not going crazy. To answer some of the above questions the shafts when fletched group well with the bare. I've had some time time to shoot it over the past few days and this set-up flys well. I think I may try some shafts that are around .530 deflection to see if I can get by with a little less point weight. I like the EFOC stuff but don't like arrows so heavy I have to account for such drop at 30 yds.

giff · April 03, 2013, 04:55:00 PM

from my experience, with your draw and poundage, you shouldn't even need that much weight on a 5575.