I have some cedar arrows that have to be made up. How do I figure the spine on them like aluminum's. I am currently shooting 2117's.
BGF, The only real way to measure spine (for wood) is with a spine meter. There are no "pre-set" numbers that you can apply to determine wood shaft spine unlike the other materials. Wood spine is measured when you support a shaft on supports 26" apart and hanging a 2# weight on the center of the shaft, then measure how far the shaft has bent (sagged) under the weight.
If you do a search here, you can find information about "home made" spine testers.
Arne
I had no idea that is how it was done. Interesting I say Interesting.
What weight and type of bow are you shooting and at what draw length? That information will give you a starting place, however if you haven't shot cedar before, you might be well served to get some of the 'test kits' that are available, which will give you three different spined arrows, and you can see which one flies the best.
Moebow and Centaur are correct-I will add that 2117 is a pretty stiff shaft, happens to be the only non-wood shaft I have any personal experience with. As a very rough comparison-if all else is equal-it would compare to a 70# cedar shaft. The deflection of a 2117, or amount force required to bend the shaft is higher (80/85); but I would compare it to about a 70# cedar, cut to the same length and shot from the same bow.
Do you have a trad archery shop nearby? They may have a spine tester and check those shafts for you. Maybe a fellow Tradganger with a tester lives close?
Remember to have the wood shaft grain vertical when checking the spine, the eye of the grain goes to the side. I made a home made spine tester by copying the pictures on the web and put it on my garage wall. I then used two soft ankle weights to bend the arrow. I used known spined shafts to make a calibrated scale. if you want to fletch them up and cut them to length, just to see if they fly or not, remember to line up the nock throat so that it lines up with the grain. You want the end grain to be vertical in the bow.
And having the grain all "lined up". Just what will that do for you pavan?