easy way to incress FOC% ?

Sambar · January 28, 2011, 10:28:00 PM

hi there just tested my arrows for there foc% and correct me if im wrong, my arrows are 33" i measured the half way point 16.75" then the balance point and the difference was only 2" so i divide the 2" buy 33" and got a foc of only around 6, i know this is low. my over all arrow weight is around the 690gr how much weight should i add up the front and whats the easiest way about doing it?

**DONOTDELETE** · January 28, 2011, 10:45:00 PM

what type of shaft?

point weight, insert weight, tub weight, footing

Sambar · January 28, 2011, 10:46:00 PM

mnt ash wood shaft with 125gr point

sweeney3 · January 28, 2011, 10:48:00 PM

Shoot a bigger point.

Sambar · January 28, 2011, 10:51:00 PM

yea i figured that but i was wondering if there is some easy ways to add weight to the front as the broad heads i have are brand new.and how much weight ruffly should i be looking at

**DONOTDELETE** · January 28, 2011, 11:00:00 PM

just ran some numbers for You and Your at 17.06% FOC

**DONOTDELETE** · January 28, 2011, 11:03:00 PM

internal footing, split-shot (lead) in the point then remount.

Ragnarok Forge · January 28, 2011, 11:05:00 PM

There are jigs you can use to drill the end of the shaft. You glue in a nail, tungsten, brass, or other rod in the hole to increase the weight.

Sambar · January 28, 2011, 11:55:00 PM

How did u get 17% foc mate my arrows are 33" and half is 16.75" and my balance point is 18.75" thats 2" infront of half so it gives me an Foc of around 6.8 % anyone have any quick or easy ways to add weight to the front?

**DONOTDELETE** · January 29, 2011, 12:04:00 AM

Rob did a program that does the math to find FOC. You can PM him or email webmaster to get a copy..

Night Wing · January 29, 2011, 12:06:00 AM

If you're shooting a 690 arrow, that's a very heavy arrow. With my 42# @ 30" bow, I shoot very heavy 32", 2117 aluminum arrows weighing 637 grains. This only gives me 15.4% FOC, but a robust 15.16 GPP (grains per pound) arrow. My very heavy arrows blow through deer on broadside shots taking out both lungs. If I was you, I'd stick with your 690 grain arrow and wouldn't worry about upping the FOC percentage.

Zradix · January 29, 2011, 04:09:00 AM

Might have to scrap the broadheads friend.

I have some 30" ash arrows.
With 125grn I was at 7%foc. (little shorter arrow is a way to increase FOC)

with 190grn tip on the same shafts I got 11.67FOC after I cut off some shaft length to stiffen the spine.

65 grains is a lot to add internally.

You could try woodyweights.

http://www.woodyweights.com/app/ProductDetails/tabid/57/Default.aspx

I worry about putting so much tip out in front of the taper. (it acts like a lever trying to break your tips off.)
Ash as you know is a whole different world from cedar though and you most likely wouldn't have a problem.

Just to be safe though you could put some steel in the tip with one of these...

http://www.3riversarchery.com/Arrow+Building+Footing++Internal+Point+Weight+and+Jig_c52_s224_p0_i5603X_product.html

And have a bullet proof aussie bomb lol

Obviously you might have to shorten your arrows a bit or get some stiffer spine.

Good flight trumps high FOC everyday.
But if you can have both..why not

Good luck!

Benny Nganabbarru · January 29, 2011, 04:51:00 AM

How heavy is your bow? I know I've read the details before, but I can't remember. Chances are that it'll work just fine as is, on any game shy of camels and buffalo, and maybe scrubbers. So, it might not be necessary to scrap your arrows, and the next time you order shafts, you could get them five pounds stiffer and go up to 160 grain broadheads. That's all I have up-front on 690 grain to 745 grain wooden arrows, shot out of bows from 63# to 83#. I'm very confident with this sort of set-up. Ben Maher once told me that the only arrows people used were cedars with 125 grain broadheads, and they worked fine.

Sambar · January 29, 2011, 05:54:00 AM

Bow is 60# at my draw 30"

drewsbow · January 29, 2011, 09:00:00 AM

well it looks like you can cut some off to stiffen the spine and add woody weights to get your %foc up. I use them on my carbons and love them .

Night Wing : I am shooting 840 gr out of my 42@28 mojo drawn to 31 so maybe close to 50 # at my draw and they shoot great. 690 is not all that heavy imho , I like heavy arrows . My setup brings my point of aim to 25 yds and works very well for me . Drew

Friend · January 29, 2011, 09:48:00 AM

FOC AMO Standard Formula

% FOC= (Dist. Knock throat to balance point - 0.50) divided by (Shaft Length BOP) X 100

Rob DiStefano · January 29, 2011, 10:13:00 AM

download and run this simple foc spreadsheet calculator ..

FOC_CALC

foc should be your last consideration for a hunting arrow. you want an arrow of decent weight (at least 9gpp) that flies great outta your bow and has a sharp coc broadhead.

upping foc means sticking more weight on the arrow front end and/or reducing weight on the tail end.

you can increase front end weight with heavier points, nail internal footings, wood external footings, and "woody weights".

changing woodie balance can be critical to the arrow stiffness/spine, unlike carbs and alums. do the testing.

Zradix · January 29, 2011, 02:33:00 PM

QuoteOriginally posted by Rob DiStefano:

....changing woodie balance can be critical to the arrow stiffness/spine, unlike carbs and alums. do the testing.

Really?
I've only shot wood out of tradbows.
I didn't realize adding wt to the tip of a carbon or alum shaft didn't change the spine much.

Seems it would no matter what the material.
Interesting.

Rob DiStefano · January 29, 2011, 05:07:00 PM

QuoteOriginally posted by Zradix:

QuoteOriginally posted by Rob DiStefano:

....changing woodie balance can be critical to the arrow stiffness/spine, unlike carbs and alums. do the testing.
Really?
I've only shot wood out of tradbows.
I didn't realize adding wt to the tip of a carbon or alum shaft didn't change the spine much.

Seems it would no matter what the material.
Interesting. [/b]

yup, IMO, really. shaft material matters to a great degree. i use wimpy 500 spine weak/light carbons with very heavy front ends pushed by 55# - they fly like darts and kill things. carbon had a very large 'n' wide dynamic spine range (i.e. 35/55, 55/75) that you won't find with woodies. so, woodies are at least a tad more challenging for me when it comes to shaft spine and front end payloads. essentially, i don't mess much with woodie foc.

Zradix · January 29, 2011, 08:44:00 PM

I see.
I've noticed some woods seemed "snappier" than others. I figured a little of this was to do with the elasticity differences between wood species.
I also thought more of it had to do with the density and or foc/size of feather differences.

Have to admit, I have seen the 35/55etc spine ratings on carbon shafts. I took it to mean the shafts weren't spine matched well from the manufacturer.

Guess I learned something today!
Thanks