Measuring Arrow Spine

[bjrogg]

I made an arrow spine tester similar to Bill's. Its still not complete right now I'm using our shop magnetic mount micrometer. I know things like length of arrow, tip weight etc. will change spine but to figure my shafts spine I was looking for chart and found this math formula is this correct. 26" between post so 26" divided by deflection from 2lb. weight equals lbs. of arrow shaft spine     Example    26/ .5" = 52 lb. spine. If this formula is correct I really don't need chart.

[Aaron H]

Looks like that formula checks out to me bj, according to the chart I have anyways

[DC]

Do a Google search on "amo spine chart"

[Pat B]

Do a Google search for "James Hill Spine Tester". There should a spine chart there.

[bjrogg]

Thanks guys. I red Oiser shaft check out at 62 lbs. I made arrow 31" long with 125 grain field point bare shafted it and it flew nice and straight. Seemed a little heavy forward and over all wieght about 3 grams higher than my others so I filed off 3 grams from front 1/3 of shaft. I'll have to bare shaft it again but I'm thinking it should be pretty good. I'll see tomorrow, I suppose it could be a little higher spine now with removing wieght from front