Tuning for Dymanic Spine

[Barry Winner]

I'm attempting to tune GT trad 3555s to my Martin Hunter.  Here are the specs:  Right handed shooter, FF string, 29" draw length, 53 lbs. at that draw, 30" shaft, standard insert, 250 grain field point, shooting at 15 yards into a fairly worn block target.  At 15 yards I'm getting nock about 2" right of the point and the point is slightly to the left of my aiming point.  I believe that means a little too stiff.  I have points from 125-250 and 50 and 100 grain brass inserts to try also.  Is that close enough or should I try a different combination?  Suggestions?  Thanks.

[Ken999]

http://bowmaker.net/tuning.htm

Try bareshafting.

I'd guess your 3555's are weak based on my results with them out of my 45 lb Bear Grizzly. I draw 28", and 175-200 gr bareshaft good with 30" 3555's.

I couldn't get the 3555's to shoot out of a 53 lb RER test bow either...too weak...

[Dr. Ed Ashby]

Barry,

No, that's not close enough. When you get them tuned 'right on' they should shoot virtually perfect, to point of aim, at 20 and 30 yards. I leave mine so that the group center consistently shows about 1 1/2 to 2" of weak-spine impact at 40 meters; about 44 yards. The fletching will stiffen the dynamic spine a tad, and they will then be right on target at each of the ranges - at least to a level of accuracy far exceeding my ability to shoot.

Follow the link Ken has above. It will guide you through the bare shaft tuning. You can also bare-shaft tune by starting with the tip weight you want to use and then progressively shortening the shaft in small increments until the dynamic spine is correct.

Ed
TGMM Family of the Bow

[R H Clark]

With carbons you should never cut them to a certin length and then try to tune.If they are already all cut you might be able to tune them but it wil be a lot harder and you might end up with a little less than perfect tune.

[Diamond Paul]

I would guess the arrows are weak, and you are getting some kind of false indication of stiff.  Those arrows are horrendously underspined for me at 29+ draw, 30" arrow, with nothing but 125grns up front, out of a 45@28 recurve.

[Barry Winner]

Thanks guys.  I've read the OL tuning guide and I'll try that.  I thought my form was pretty good, but I guess I may have some release issues that could be giving me a false reaction.  RH, just an fyi for ya', the shafts had not been cut, that is full length for 3555s.  Thanks again.