understanding arrow specs

jimmy250favre · 08-22-2007, 08:27 PM

I need some help with arrow specs, this is something that I know will be very useful for me in the future. Can anybody out there tell me differences and the meaning between numbers like 4560 and 6075 and how they relate to an arrow like the maxima 250 or 350. I appreciate anybody's insight and input.

TFOX · 08-22-2007, 08:39 PM

The 4560 means the arrow should be good for bow between 45# and 60# but rarely is that accurate.A bow that is 30" draw will have much more energy than one that draws 27" so how can the same arrow spine for both at the same poundage.ANSWER,it can't.

The carbon express numbers seemed to be pulled out of the sky and I have no idea where they derive from but the maxima 250 has a .404 spine and the 350 has a spine of .344.Meaning the 350 is stiffer.

The spine is how much deflection a shaft has when a certain amount of weight is pulled from the center(2# I believe)of the shaft over a 28"span(I think).

Easton arrows are really simple to understand.If the arrow is a 300,it's spine deflection is.300

The aluminum arrows are really simple.If you have a 2213,the outside diameter is 22/64 and the wall thickness is .013 thick.

jimmy250favre · 08-22-2007, 08:50 PM

that helps a lot, thanks for the reply

Straightarrow · 08-23-2007, 05:26 AM

If you want to understand it, you have to start thinking in terms of deflection. Spine is the measure of the deflection in fractions of an inch for a 28" shaft with a 2 lb weight hanging from it. Lower numbers equal less deflection, equals stiffer shaft. The numbers that relate to draw weight are worthless to many, so it's not worth learning them all.

Every shaft with the same spine rating, should fly similar out of a given setup. For instance, I have learned what tip I want with a .340 shaft at 63 lbs out of my setup. I also know that if I use a .350 shaft, that I need to decrease draw weight by about 3 lbs, or reduce tip weight by about 20 grains at the length I shoot them. Knowing these relationships enables me to quickly get close on the spine I need with the tip weight I prefer on most shafts, even if I'm not familiar with them.

I would still never rely on this to configure an arrow. I always tune it in the field. Neither software or rules-of-thumb will get it exactly right. The only true spine tuning takes place on the range.

Roskoe · 08-23-2007, 01:19 PM

Comparing the flight and point of impact between bare shafts and identical fletched shafts will tell you a lot about how close the spine is to being perfect for the bow's draw weight and draw length.

09mjl01 · 08-23-2007, 09:44 PM

what spine should i be looking for if i shoot 29" draw and a 29" arrow with a 100 grain tip and 55# draw? if you know off the top of your head or maybe in comparison to your set up.

Straightarrow · 08-24-2007, 04:36 AM

Quote:

ORIGINAL: 09mjl01

what spine should i be looking for if i shoot 29" draw and a 29" arrow with a 100 grain tip and 55# draw? if you know off the top of your head or maybe in comparison to your set up.

It is more complicated than that. It also depends on the bow. The type of cam and power stroke distance greatly affect the force applied to the arrow. To get a real accurate recommendation, it helps to crono an arrow and to give the specifics of that arrow.

You can shoot most spine ranges if you're willing to adjust tip weight, arrow length and/or draw weight. A 100 gr tip on an arrow that long won't put much weight up front. That isn't the best for broadhead stability.