How does front end weight affect spine weight

[Norseman]

I am wondering if there is a formula to determine how forward weight of an arrow affects the spine.

For example.

If my bow draw weight is 47lbs at 28 inches and I run a .500 spined arrow,   but want to shoot 400 grains up front, how much will it affect that spine?  And will I likely need to go up in spine for that much weight.

Your thoughts and experiences are appreciated

Thanks
Paul

[Tajue17]

just in my own words but basically when you release the arrow it has to push against that 400grain point to get that arrow moving which weakens the spine of the shaft.

one of my bows can shoot a bareshaft heritage 150 with a 225grain point perfect like a dart, the same bow shooting the same shaft now with 125gr point bare shafts it very stiff with a nock right @ 10yds.

[Don Stokes]

Increasing point weight definitely affects spine. When I go from 125's to 190's, I have to go up 5#, or cut off an inch. The more weight added, the more spine needed. My formula is called "trial-and-error".  

[ishoot4thrills]

Paul,
Click on this link and download it and you'll see an amazing "spine calculator". Experiment with it!

 http://briefcase.yahoo.com:80/bc/[email protected]/vwp2?.tok=bcCz6kcB3cFO.9ke&.dir=/Public&.dnm=Dynamic+Spine+Calculator+Rev3-20-09.xls&.src=bc

Doug

[Norseman]

Thanks everyone I appreciate the replies

I have known that a heavier point weight will make an arrow perform like a softer spine, I just wanted to know if there was a formula on how to determine what will work

Much appreciated guys...thanks

And thanks Doug for that spreadsheet I will play with it.