foc and spine

[dick sable]

Is there a specific formula or even rule of thumb regarding how much shaft spine is reduced as weight is added to the front?  For example, x-number of spine pounds per grain up front? Hope that question was worded right. I have a bunch of carbon shafts spined much too heavy for my bows. Thanks.

[dick sable]

Following up my first question: I guess we would be talking about reduction of dynamic spine - how can that be measured?  Or, do you have to bare shaft and try to figure what shoots best?

[JRY309]

I find the correct dynamic spine from bareshafting,the only true way I know of.But you can also get false readings.I had some carbons that were showing stiff,so rule of thumb was to increase front end weight to weaken the spine.Well they got worse the more weight I added,they were bouncing off the riser instead of flexing around it because carbon recover so much faster.This can happen with carbons on bows cut off center,the arrows were cut 1" past my draw.If they were longer they may have tuned for the bow I was tuning them for.I feel bareshaft shooting and testing is the best way to find the correct dynamic spine for your bow and arrows.

[Ragnarok Forge]

Bare shaft to fletched tuning is what works for me.  Just start adding heavier heads and tune / shoot until your groups match.  Start with full length arrows and cut them down only when necessary.  To many people try to use an arrow cut to a preferred length.  Let the arrow tell you what length works best instead of fighting to make a set length work for you.

[Fletcher]

Most guys figure about 5 lb for 30 grains and that is probably a good starting point.  I don't see quite that much change with my shooting/testing, but every setup is a little different.  My experience is all with wood arrows, too.