spine calculator

runningbird · April 03, 2013, 09:02:00 AM

I'm trying to figure out the best arrow. My bow is a liberty edge 47# @ 28" and I draw 30". When I use the stu miller calculator it shows my full lenth GT 55/75 with 150 point and 50 gr insert to be way to week. it wants me to go down to a total of 110gr tip including insert. my arrows hit where I aim but I can see that they don't fly perfect. I do how ever get a perfect tear thru paper. I would like to try arrow dynamics but not sure which to buy.
any help or ideas would be appreciated.
thanks,
Mark

Bud B. · April 03, 2013, 09:16:00 AM

Can't speak for the calculator but have you tried heavier points? My experience tells me that the calculator has carbons overspined. You need more point weight to reduce the dynamic spine.

Try some 175 an 200 gr points and see what happens. Maybe even 225gr points

I don't paper tune or bareshaft. I shoot fletched arrows to get good flight then move to broadheads after that.

Sometimes a false nock high is the fletch hitting the shelf. Try cock feather in also.

runningbird · April 03, 2013, 09:19:00 AM

thanks for the reply, I do shoot cock feather in.

I was just trying the calculator because I had hear such good things about it. But it also does not list my bow. and it does not list the AD lites that I think may work.

April 03, 2013, 09:44:00 AM

The Gold Tips will work but I also think they are a bit underspined. I shoot 50# at my 29.5"DL and shoot 55/75's at 32" with 250gr up front to get them to tune correctly.

You are shooting a bit more poundage at your DL. If you shorten the shaft a bit at a time you should be able to get those shafts correct.

Bisch

Shawn Leonard · April 03, 2013, 04:09:00 PM

I think a 31" 55/75 with at least 200 grains of point weight will get ya close. I think you still may need to add a tad more weight. The calculator always has people overspined on carbons, as much as 20#s. Shawn

runningbird · April 03, 2013, 05:18:00 PM

not sure if this will work, but this is the calculator page with my info.

file:///C:/Documents%20and%20Settings/smith/My%20Documents/spine%20calculator.htm

Bud B. · April 03, 2013, 06:07:00 PM

Can you do a screenshot and post the pic of that?

The link is dead.

runningbird · April 03, 2013, 06:52:00 PM

took me a bit to figure it out.

Onehair · April 04, 2013, 10:23:00 AM

I think the input on the arrow shelf is causing you problems. Is the bow center shot ? Do you have shelf material? Most longbows are not cut to center.
When adjusting that I think you are pretty close with your set up. If @ 32" I get 195 up front total or 31" your dead on. Recheck your actual bow specs and re-enter. Also I find a big difference in how bows scale vs how they are marked. No matter find what you can bare shaft the best.

Car54 · April 04, 2013, 12:09:00 PM

The Edge is cut .125(-1/8) pass center.

east_tx_pineknot · April 04, 2013, 08:30:00 PM

The calculator has always been spot on for me but strike plate position is an important number to get right to have accurate results.

runningbird · April 04, 2013, 09:30:00 PM

Thank you everyone. thanks Car54 for the edge info. when I enter that into the calculator it shows that I am dead on....