Spine and Weight

[Rick James]

For you guys that have messed around with wood arrows--In your experience how much does point weight affect the dynamic spine of an arrow--I have read that cutting or adding an inch to the  standard 28" shaft will put the spine into the next 5# range up or down but have not seen in print how much weight affects spine??
thanks, Rick

[JRY309]

That is a general rule to add or subtract 5# spine for arrows 1" longer or shorter.There is no real formula you can calculate the affect on dynamic spine other then shooting it for yourself.

[Art B]

I would think that the different weight points available today have a direct relationship to spine ranges (e.g. 100, 125, 145, 160, 175, 190gr). But then again one most take into account the degree of arrow pass. For the selfbows I shoot those numbers represent one spine range (5#) for me. Perhaps two or more spine ranges for center to past center shot bows. Not for sure on the last one so maybe some of the glass folks can help you there. After awhile you'll develope your own formula.

[aromakr]

Rick:
The influence of point weigh will depend where the spine your testing falls within your usable range. Too clarify that some lets say you can use spines from 40-55# and the shaft you are testing spines 55# it will handle a heavier point than a 40# spine shaft, so its difficult to give a definitive answer.
Bob

[Fletcher]

I can go from 125 to 160 gr without much difference being noticed.  Stepping up to a 190 gr broadhead seems to need a higher spine, but I believe the length of the head has as much to do with it as the weight.

[Magnum in Ms]

For me and my bows it seems like a jump from 125 to 160 gr point needs about 5 more lbs spine