Help me get EFOC.

[RedTape]

#5366

EDIT: Lets simplfy things.
I’m shooting a 46# longbow with a 26 1/2 inch draw length. Assuming I’m using a 100 grain insert and 160 grain Grizzly broadhead and I get Beman MFX shafts cut to 28 inches, should I go with the 400 or 500 spine?

The Beman website says 500 (no option for point weight, so I’m assuming they base it off a 125 gr. point), but I’m thinking with the extra weight up front (260 gr total), I’m going to need the stiffer 400s.

[David Petersen]

#41182

Could go either way, as carbons are extremely accommotading in spine. I can shoot 125 up to 315 heads on the same shafts without retuning. Guess I’d go with the 500s as you can always add more weight to the front if they’re too stiff, but if they’re too weak and you have no shaft to cut off, you’re stuck with light heads. I am currently working to get some overspined Viper carbons that a friend gave me, to shoot well after being cut to my length. Have fun, dp

[Ed Ashby]

#42388

Red Tape, there’s no ‘cook book’ answer to what shaft will tune with what tip weight, draw weight and draw length. There are a great many factors that will affect what dynamic spine you are going to need. Major among these are your bow’s efficiency, the degree of center shot of your bow, your shooting technique and the quality of your release.

If it’s any help, when I initially started working with EFOC my tendency was to start with a static spine that proved to be way too stiff when I tried to tune it; but most of my bows are far from centershot. Now I always start with the lowest static spine that I think might possible work.

Ed

[RedTape]

#47765

Thanks guys. I’m going to hit up my nearest archery shop as soon as possible. They sell individual arrows so I’m going to buy a selection and start tinkering with them. If I’m doing my math right, I should end up around 24% FOC with the Grizzlys.

[Ed Ashby]

#48069

Keep us posted on how it’s going, RedTape.

Ed

[tom-wisconsin]

#63255

Redtape

I have a 40# bow but my DL is about 28 3/4 inches so I am pulling about 43 lbs. This is my set up.

Here is my set up for my 43# bow.

GT expeditions hunters 3555
Spine 0.500
Straightness 0.600 +/-
30” cut to cut
30.75 inches BOP
7.4 gpi
222 grains
9 gr nock
6.9 gr fletching
100 gr brass inserts
125 gr steel adapter
Abowyer Brown Bear 175 gr
brass washer 5 gr
Balance pt 24.75 “
FOC 30.48%
645 gr total wt

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