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Author Topic: ashbys arrow  (Read 1470 times)

Offline calgarychef

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ashbys arrow
« on: March 04, 2012, 12:43:00 PM »
I was reading the Ashby reports today and in part 4 Dr. Ashby used the following combination with great sucess our of a 63lb.acx.  75/95 gold tip expedition hunter, 100 gr. brass insert, 125 gr. steel broadhead adapter, 190gr. grizzly.

 So I used my trusty Stu Miller calculator (I love this thing and it's worked well in the past).  Well it shows that arrow to be so underspined that I'd have to build out the sideplate 3/4 of an inch to balance everything.  

Now the only thing I had to fudge when using the calculater was that the 75/95 arrow listed was a GT Hunter not the gold tip Expidition Hunter.  Are these arrows that much different?  Am I doing something wrong?

Offline Dr. Ed Ashby

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Re: ashbys arrow
« Reply #1 on: March 04, 2012, 02:08:00 PM »
I did, indeed, have to build the side plate out a substantial amount. Also consider that this arrow shaft was just barely over my 27" draw length, which stiffens the spine.

Ed

Offline calgarychef

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Re: ashbys arrow
« Reply #2 on: March 04, 2012, 03:10:00 PM »
Doc I'm glad you chimed in!  Would you be able to recomend an arrow with stiffer spine to handle this set up out of a 63lb ACS? It's hard to find a shaft that's stiff enough to handle the EFOC idea.  

So to recap with the 53lb limbs I shoot:

CE heritage 250 cut to 28 1/2
50 gr. brass insert
250 gr heads
total weight 630 gr.

I draw to 27" but like to have a bit sticking out to aid in point on shooting beyond 40 yards.  So that compounds the problem of finding stiff enough shafts for an efoc set up.

I really like the set up you used especially considering it's only 655gr. (nice trajectory) and if I can get comparable or better penetration to the 900gr. "logs" I'm all for it.  It would also be nice to find a combination that's about 12-13 gr./lb. to have the same trajectory as with my lighter limbs.

anyone else have any shaft ideas?

Online hybridbow hunter

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Re: ashbys arrow
« Reply #3 on: March 04, 2012, 03:16:00 PM »
you can use gold tip Big Game which is supposed to be .280 (115#)  in spine but on my spine tester is rather 125#
You also have the GT kinetic big game .200 (150# !!)
La critique est aisée mais l'art est difficile.

Offline Dr. Ed Ashby

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Re: ashbys arrow
« Reply #4 on: March 04, 2012, 04:51:00 PM »
To get into the upper EFOC or UEFOC range you need a shaft with a low GPI weight. It's near impossible to get the right combination on a bow cut past center, and difficult on bows cut to center. Building the side plate out is a tuning tool that helps a lot, when trying to tune a high EFOC or UEFOC arrow.

Ed

Offline Andy Cooper

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Re: ashbys arrow
« Reply #5 on: March 04, 2012, 07:03:00 PM »
Hi Dr Ashby,

What is considered low gpi? Also, do the EFOC and UEFOC arrows only need 3" or less fletching? Does the turbulator strip compensate for less fletching, or is it the weight up front? Thanks!
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Offline stalkin4elk

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Re: ashbys arrow
« Reply #6 on: March 04, 2012, 07:32:00 PM »
FWIW, I shoot a 60# Centaur(efficient)hybrid at 28.5 draw and use 75/95 GTs that are 29 3/8 B.O.P. to the nock groove and they are just a hair weak and I can't cut them any more due to hand clearance.  Approx 1/4 inch of that length is brass adapter.
I use 100gr brass adapters and 260gr points/Bhs fletched with 2 rw 4 inch parabolics.
Length matters.
Recently got some 300 spine GT Ultralight shafts and cut some AA 2.5 inch fletching to try but am concerned they may show weak with the weight I want. I like the EFOC thing and want to be between 650 to 680 grains total...just need spare time to tinker.

Offline stalkin4elk

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Re: ashbys arrow
« Reply #7 on: March 04, 2012, 07:55:00 PM »
I forgot to mention I tried the same 75/95s with 300 to 325 grains up front and had to build the side plate so much the shelf almost dissappeared. I did not like that at all, so I backed off to the 260 GR. which allowed for Aboyer Brown Bears with 100 grain adapters.
I would like to try Tuffheads but may have to use titanium adapters which is a $$$$ in my savings.

Offline Dr. Ed Ashby

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Re: ashbys arrow
« Reply #8 on: March 04, 2012, 08:27:00 PM »
Jim, you have several 'tools' to work with in developing your EFOC/UEFOC arrow. One is to build out the side-plate but another is use either an internal or external footing, both of which will increase the dynamic spine. The longer the IF or EF the greater the dynamic spine will be.

Ed

Offline stalkin4elk

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Re: ashbys arrow
« Reply #9 on: March 04, 2012, 08:42:00 PM »
Thanks Doc.
My setup,arrow and bow, is close to good ole' KINGWOULDBE except the dreaded alum adapters. The EF should significantly reinforce the alum adapters I think. I have used your wooden dowel IF recipe for my Son's set up with a 45# recurve and your penetration enhanced arrow guidelines...thanks for the huge help on info!
A side note is that my Son shot in our state 4H tourney today and you should have seen the limb vibation from a lack of tune on waaay too many recurves...like the shocks at Baha 1000! There was a good showing of trad gear which was great to see.
Short draw length is an advantage for EFOC it seems.

Offline JamesKerr

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Re: ashbys arrow
« Reply #10 on: March 06, 2012, 07:55:00 PM »
I'm glad this came up as I have wondered the same thing about how weak the arrows seamed for the tuning. I am glad you chimed in Doc.
James Kerr

Online ozy clint

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Re: ashbys arrow
« Reply #11 on: March 06, 2012, 10:32:00 PM »
cooking up some buff arrows hey chef?
75/95 should work for you.
i shoot them out of my 69# recurve with 350gr point and insert weight plus my special weight tube weight behind the insert which weigh 170gr. the rest of the shaft is filled with 3gr/" weight tube. 890gr total.

what head do you plan on using?
Thick fog slowly lifts
Jagged peaks and hairy beast
Food for soul and body.

Border black douglas recurve 70# and 58# HEX6 BB2 limbs

Offline calgarychef

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Re: ashbys arrow
« Reply #12 on: March 07, 2012, 04:22:00 PM »
Ok some questions before I send my hard earned money away for shafts. I've narrowed it down to 3 choices:  All are from 3R in case anyone wants to look at them.

carbon tech panther-40/80 lb. spine, this is a tapered shaft approx 8.5 gpi.  It's interesting because you can cut from the front or back of the arrow for tuning purposes-it might be a nightmare for tuning though. I think it takes standard inserts which appeals to me.  The taper is a "true taper" front to back so is probably better to deal with than the hammer heads that are "heavy footed"

Carbon tech rhino 55/80 lb. spine (.300), 11.5 gpi.  This sounds like a tough shaft!  

arrow dynamics hammer head-the heavy weight is a .205 spine, takes special inserts, about 490 gr. total weight.  It's got a "heavy footed" shaft and the taper starts about 14" back so even though it's got built in foc it's in a gradual manner.  I'm a bit leery of this idea simply because I've had troubles with the grizzly sticks and they are similar.  I do like the .205 deflection though.

Does anyone have specific experience with any of these shafts?  They all sound good.  The carbon tecks are both low gpi. compared to other shafts of similar spine.  

I'm eager to hear of any experiences!

Offline stalkin4elk

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Re: ashbys arrow
« Reply #13 on: March 07, 2012, 09:34:00 PM »
I have tried the AD HHs and some like them but I am not a fan because they have a lot of weight variation and if you want EFOC they are way too heavy with only a bare shaft w/o inserts.
Try the 300 Gold Tip Entrada Ultralight to begin with at 8.7 gpi approx. and reasonable price.
I have no experience with Carbon Tech.

Offline calgarychef

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Re: ashbys arrow
« Reply #14 on: March 08, 2012, 03:12:00 AM »
stalkin4elk, are the gold tips a strong arrow?  I could use any number of arrows but I want something tough as nails in case I get to so for something big some day.

Online ozy clint

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Re: ashbys arrow
« Reply #15 on: March 08, 2012, 04:36:00 AM »
chef- i shot my buffs with cheapo expedition hunter gold tips. they've never given me a reason to change.
Thick fog slowly lifts
Jagged peaks and hairy beast
Food for soul and body.

Border black douglas recurve 70# and 58# HEX6 BB2 limbs

Offline stalkin4elk

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Re: ashbys arrow
« Reply #16 on: March 08, 2012, 09:37:00 PM »
CC jump over to PowWow and do a search on carbon arrow INTERNAL FOOTINGS and also EXTERNAL FOOTINGS and you will have lots to read about tank buster arrows.
I will say I like the GTs better the ADs and Easton FMJ but do like the Easton ALL carbon Axis shafts. All are strong but not bombproof w/o footings.

Offline JimB

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Re: ashbys arrow
« Reply #17 on: March 10, 2012, 11:19:00 PM »
First,Stu's calculator is a good tool but it goes haywire with anything over normal FOC.With high FOC setups,it shows way too weak.

If you want to get in to the higher range of FOC,check out the Victory V Force,HV's. .300 spine,6.9 gpi..350 spine,6.7 gpi..400 spine,6.2 gpi.

They seem to need a little more point weight than other shafts of equal deflexion.For recurves 50-55 #'s,I use .350's with app. 430 grs up front.On a 30" arrow,this comes to just under 32% FOC.My bows are cut about 1/8" past center.

Offline Andy Cooper

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Re: ashbys arrow
« Reply #18 on: March 11, 2012, 09:38:00 PM »
Ok, showing my ignorance, but that is nothing new for me. Why do weak-spined arrows with the side plate built out work better for this application than stiffer arrows in a closer to center-shot bow?  :dunno:  

Thanks!
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Offline calgarychef

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Re: ashbys arrow
« Reply #19 on: March 12, 2012, 04:42:00 AM »
Andy they are only weaker because there is so much point weight.  The point weight resists foreward movement at begining of the arrows movement so the shaft flexes more to take up the force being applied to it.  What we're looking for is a stiff, light, skinny shaft.  

The only reason to build out the sideplate is because of the shafts weakness.

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