I remember reading somewhere in the 1000's of pages I've read here, a formula for woodie spine, something like add 5#s for this and 5#s for that,I can't find it anywhere. any one know of this? do'es it work well for a starting place? thanks Burt

Lots of variations and all are "estimates" not hard and fast.

Add 5 for about every 30 grains of point weight increase, subtract for 30 gr decrease.

Add 5# for a fast flight string (changing from Dacron)

Add 5# per inch increase in arrow length, subtract for each inch decrease.

Add 5# for centershot compared to not centershot.

Arne

Thanks Arne,Is there a starting weight for the point wt? 125gr? Do'es arrow length start at 28in ?

Yup, starting weight 125 grains for points; arrow length figured from 28".
I remember reading that formula also, in fact I think it was written a couple of times by a couple of different folks, same info as Arne offered above(except folks were saying 5# for every 25 grains point weight, up or down). That pretty much sums up the formulas as I recall.
I do wonder, though, how spine changes relative to just how far from centershot a bow is.. 1/16", 1/8", etc.

I use Arne's formula with slowbow's adds and add 5# for each 1/16 cut past center-I made that up based on my own experience with bows cut 3/16 past and it works.

Draw length is more than 28", add 5# per additional inch

Draw length less than 28", subtract 5# per inch.

Shooting recurve or high performance LB (shelf cut to center or past center) add 5-10#

Using FF string material add 5#

Point weight is more than 125grs add 1# for each additional 7grs.   (i.e. 145gr points = add 3# spine)

Thanks everyone that's just what I was looking for. Burt