I dont have a spine tester, so I weighed all my bare shafts and seperated into groups. I have them in groups within 5 grains. 343 to 348, Next group is 369 to 374, etc... My question is this. Will the arrows within each group be close to the same spine? Would the arrows in the lighter grain groups have more flex and the heavier be stiffer? If so ,Can I adjust my tip weight to get them to fly the same? This my my first adventure into woodies and I want to do it correct the first time....Thanks Roy

your spine could be and most likely is not the same. A SPINE IS THE BEST WAY TO TEST YOUR ARROWS  
                          GOOD LUCK

SORRY A SPINE TESTER IS THE BEST WAY TO TEST YOUR ARROWS

You could have 100# 300 grain arrows and 40# 400 grain arrows, they aren't related...O.L.

I talked to my uncle and he said they were spined 55/60#. If I have an arrow that say is 80 grains heavier wont this affect the way it flies compared to the lighter arrow.The heavier will drop more wont it? Can I add weight to the light one and get the same flight or not have to change my aiming point?
It was slow in the woods tonight and the more I thought the more confused I got. I'm learning that there is alot more to wood than my carbons thats for sure.

Blind One, "Can I add weight to the light one and get the same flight"

No, it doesn't work that way. It depends on where the weight is located as well. For a few grains, just an extra coat or two of finish helps. Personally I don't worry too much about weight. Spine is more important at hunting ranges. The closer the better of course...O.L.

Thanks guys,
I'm learning more everytime I read stuff on here..Thanks again
Roy

Weight has nothing to do with the spine of the arrow.  
You can make a rough spine tester by putting 2 nails in your work bench 26" apart to support a shaft then hanging a 2 pound weight in the middle of a shaft.  The deflection isn't going to tell you what the spine is but if you mark the bottom of the arc it will give you a rough estimate of where your other arrows need to be to be close in spine.