How do you determine the spine of an arrow?

[stinkbelly]

I inherited about 75 wood arrows and I am wondering how I can determine the spine of these arrows.  These arrows are all new or slightly used and not more than a couple of years old.

[freefeet]

Put them on a spine tester.

[McDave]

Here  are some spine testers that are sold by Three Rivers Archery.

[Hot Hap]

If you don't want to buy a spine tester, you can take 2 nails and space them about 6-8" apart horizontally. Leave a small space between them so the shaft is level, and take a aluminum shaft that has a known spine and hang a pound or so from the end of the shaft. Mark where the shaft hangs. Put the wood on and if it is below the mark it is a lighter spine. Above is heavier. Hap