I'm shooting XX75 2016 shaft at 29 inches. Can someone with a spine meter tell me what spine of wood shaft will spine out like this 2016? Thanks, Gapmaster
A 2016 is 59.3 pounds spine. To calculate spine of aluminum or carbon divide 31.5" by the deflection listed.
For 2016: 31.5/.531= 59.3lbs.
I have verified the calculations with measurements.
Sweet. I didn't know that math calculation. Thanks for the help. Gapmaster :)
type in "arrows by kelly" and it will take you to foxfire, look at his charts. 61# to 63# for the 2016's
Cupcake; do you recall where the K Factor of 31.5 in your formula came from (what standard)?
I have always understood that the Factor was 26, but I cannot remember where that number came from. I'll keep looking.
Al (Als Decals)
The 31.5" comes from a derivation that converts the ATA (AMO) 26", 2#, method to the 28", 1.94#, ASTM method that is used for aluminum and carbon arrows.
When I was developing the Spine-O-Meter I used beam deflection theory to derive the conversion factor. The result is that the deflection of a carbon or aluminum shaft measured on the wood ATA standard (26", 2#) is 0.825 x the ASTM deflection. For a 2016: .531 x .825 = .438. So 26/.438 = 59.3. The more direct approach is 31.5/deflection since 26/.825 = 31.5. I have a write-up of all of this math for anyone that gives me their email address.
I'd like to see the math Kevin, if you would. anhharford@comcast.net.
I developed my own spine meter along with all the spine / draw weight charts using the 26" / 2# method but also a 1# set for lower weight arrows. I used a dial indicator and when loaded with light arrows, the plunger penetrated the base, thus the 1# weight.
Thanks in advance for sharing.
Al (Als Decals)
center cut bow you can do higher
Cupcake, does your spine-o-meter have shaft sizes (alum and wood) listed where the needle points when your spining out a shaft? Do you have these for sale? I think I need to add one to the shop. :) Thanks, Gapmaster
Gapmaster,
Yes it does have the wood, aluminum and carbon all on the same scale reading. Check the sponsor classifieds and you will find the details and photos.
Kevin
Kevin, if at all possible, I would like to see that write up too.
vcorpus@ptd.net
thanks,Vaughn