Set up for EFOC arrows.

[George Vernon]

A lot of good press has been shared in recent years about extreme forward of center arrows.  Many folks seem to take advantage of stiff carbon arrows and add brass or other heavy weight inserts and field tips/broadheads.  The extra weight up front reduces the dynamic spine and increases FOC.  Tips like Woodyweights would appear to allow the same thing for wood arrows.

I've done this for a number of arrow and bow combinations and get generally good flight and bare shaft tuning results.  But when ever I go back to some good old wood or aluminum shafts that have more conventional FOC, my shooting impression is the conventional shafts are more stable in flight.

Some folks have shared with me EFOC can move a bit more side to side than conventional FOC at the moment of launch and maybe what I'm seeing is a bit of that initial movement.

What is your experience?

[Friend]

Of my limited experince, my latest Ultra-EFOC set-up flies visibly truer than any of my previous and numerous set-ups.

[Rob DiStefano]

as much as it would appear to fly in the face of both physics and conventional wisdom, in all my personal efoc testing, with an emphasis on "extreme" (22% to 28%), adding a lot of up front weight didn't affect my arrow's flight to any significant, or even perceived, degree.  i do not bare shaft test.  i just pile on the weight.  important to add, my 4-fletch bananas are 4" long, taped on nearly straight with no helical, and a low profile height.  again, this is for me and your results may vary.  shooting bows is first and foremost about form ...

[ishoot4thrills]

I get the best results I've ever had with my current EFOC arrow setup, even with more than one bow and the same arrow. Whenever I trade bows and use the same arrows, I generally experiment with my strike plate thickness to get it right. I bare-shaft tune by using the "fletched arrows grouping with bare-shafts" method.

My specs are in my signature below.

[Jason R. Wesbrock]

George,

There's probably a good reason why 10-15% FOC has been the norm for hunting arrows for decades. That's not to say EFOC won't work; far from it. A lot of folks kill a lot of animals with it every year, just like a lot of folks have killed a lot of animals with normal FOC for generations. They both work, and to me, one versus the other has always seemed a silly thing for people to argue over.

Proper tuning is the key, which is why I'm glad to see you took that step. I would be willing to bet a paycheck that improperly tuned arrows are the number one reason why some folks think they need cape buffalo setups to shoot through a whitetail deer.

[Orion]

George:  One of the problems with front loading wood is the decrease in dynamic spine that it causes.  Dynamic spine decreases for carbons as well, of course, but usually we start with woods that are more closely spined/matched to our bows, so a relatively small change in dynamic spine can throw the arrows out of tune.  I usually use wood shafts 10#-20# heavier than I would normally use when I add say an extra 100 grains to the front (usually through an internal footing).  WhenI do that, I get good arrow flight.

[Rossco7002]

ishoot4thrills,

How far from centre is the strike plate on your current set up? I'm curious as I've got a very similar arrow/draw weight configuration.

[Fletcher]

So far, I've had pretty good luck with high FOC wood arrows.  Arrow flight and penetration performance have been very good.  As a shaft material, wood has it limitations regarding increasing FOC; arrow weight and spine limit out quickly.  21% is about as far as I've been able to go in a working arrow.  It's a Sitka Spruce shaft, 28" BOP and 70 lb spine with a 50 gr lead insert up the nose and a 190 gr broadhead.  It paper tunes beautifully from my 54 lb @ 26" Pronghorn LB.  I call my nose weighted arrows "Heavy Heads".

I've figured out that I need to go up about 1 lb of spine for each 10 gr of insert and 7-8 gr of point weight.

 

[George Vernon]

My thanks to all who have shared their experiences.  I have been working with 55/75 Gold Tips, 100 grain brass insert and 170 gr. broadheads.  On an Ace spine tester, the 55/75's vary a bit, but typically show a static spine of 75.  Many folks suggest dynamic spine will change about 1# for every 5 grains added to the end of an arrow. So I thought the heavier insert would drop the dynamic spine 15-20# and I would end up with the same value spine as I had with the aluminum.

When shooting these arrows, I could pick up a bit of side to side movement I could not see with aluminum arrows of about the same mass weight, but smaller FOC.  At 20 yards, both types of shafts did well with bare shaft tuning.  So where does the brief side to side flutter come from on the carbons?  (the carbon and aluminum shafts are 5/16 od, so center shot was the same)

I may have some new insight.  I've been using a recurve cut 1/8" past center so I have some room to change center position of the shaft.  I thought the added weight may have decreased the dynamic spine more than the traditional rule of thumb.  So I build the side plate out a bit and the flutter went away.

At this point I'm thinking the amount of weight I added to get the desired total mass weight on the carbon shaft changed the dynamic spine more than I anticipated.

thanks again for all the shared insight.

[katman]

George, where do your broad heads impact relative to your field points both before and after the side plate adjustment?

[JimB]

With my setups,18-25 grs of point weight equals 5 lbs of dynamic spine.I don't think there is a rule of thumb.I think you just have to tune till it's right.I have had no trouble getting arrows tuned from 21%-31% FOC.

I believe Dr Ashby made a reply about this very subject on the Dangerous Game forum and I thought it was very well explained.

[JimB]

This is Doc Ashby's reply from the similar thread on the Dangerous Game forum:
Andy, what's important is that the DYNAMIC SPINE of your arrow be correct to counteract the amount of point weight you are using; whatever that amount might be. You're balancing the shaft's dynamic spine to the point weight you are using AND to both your individual bow and your personal shooting technique. That's the entire goal of bare shaft tuning; to get perfect arrow flight (on a field point tipped arrow) FROM YOUR BOW when shot by YOU, and WITHOUT ANY FLETCHING masking the arrow's flight characteristics.

Once a specific shaft is correctly bare shaft tuned (with a specific amount of point weight) you need only add enough fletching surface area to counteract the wind shear effect of whatever broadhead (weighing the same as the field tip you tuned with) you are using.

Carbon shafting is the easiest to build EFOC/Ultra-EFOC arrows on. It allows less shaft weight for the same degree of stiffness as aluminum or wood, and has a smaller diameter for a given stiffness.

The manufacturers specified 'spine' or 'deflection' is the "Static Spine" of the shaft. The static spine is merely a measure of how much the shaft bends when a specifiec amount of weight is suspended at the mid-point of the shaft when the shaft is susported at two points that are a specifiec distance apart. It tells you very little about what the dynamic spine of that shaft will be when shot from your individual bow. Static spine does, however, give a point of reference.

If a given shaft, having a static spine "X" proves to be too weak when you try to bare shaft tune it (with a given point weight) you have two options: (1) reduce the point weight until the dynamic spine is correct for the reduced tip weight or, (2) try a shaft (of that same type) with a stiffer static spine (a higher "spine" rating, or a lower "deflection" rating).

If that shaft with static spine "X' is too stiff when you bare shaft it, you again have two options: (1) increase the tip weight until the dynamic spine is correct for the greater tip weight or, (2) try a shaft (of the same type) that has a weaker dynamic spine (a lower "spine" rating, or a higher "deflection" rating).

Unless you feel locked into using a shaft of one exact length, it's easiest to start your bare shaft tuning with a full length shaft that shows a weak dynamic spine and then gradually shorten the shaft (which stiffens the dynamic spine) in 5mm increments until you reach the correct dynamic spine. If you reach the minimum shaft length you can use and the dynamic spine is still too weak then you have to go to the next stiffest static spine in that same shafting, and start tuning with the stiffer shaft.

Hope that's not confusing,

Ed

[George Vernon]

Katman,
Broadheads and same weight field points fly to the same point of impact after building out the side plate a bit.

The side to side movement I was seeing on the nock end of my arrow just after release, was small, but noticeable when compared to aluminum shafts of the same mass with a slightly greater static spine.  Even with this small wiggle, the EFOC carbons quickly stabilize, and no adverse down range problems were seen.

So it was never a major flight or tuning problem.  Just a difference between aluminum and carbon shafts of the same mass, and close to what I thought was the same spine.  This was my first experience with loading a bunch of weight on a carbon arrow.

Again, I appreciate the thoughtful and insightful comments from all.

[ishoot4thrills]

Originally posted by Rossco7002:
ishoot4thrills,

How far from centre is the strike plate on your current set up? I'm curious as I've got a very similar arrow/draw weight configuration.

I ain't got a clue.     I just experiment until I find the correct spot.

[katman]

Thanks George, I am also curious if the broad heads grouped with the field points before you built out the plate, or showed weak. I am thinking your were on the weak side of the tuning parabola and curious if the broad head picked this up or not. Also what type of broad head? Thanks.

[Ragnarok Forge]

My experience has been that EFOC arrows fly better than standard or high foc arrows.  I find EFOC arrows are easier to tune.  They are more  forgiving of minor errors in form.  I am shooting mine with four 3 inch fletch.  I find they have far less drift in a cross wind. The four 3 inch fletch also control my broadheads perfectly.  Having shot all levels of FOC I will not be going back to average or high foc arrows.  Standard arrows will kill animals.  EFOC arrows give me the edge I am looking for when an off shot leaves me needing a bit of extra penetration.

[Rob DiStefano]

Originally posted by Ragnarok Forge:
My experience has been that EFOC arrows fly better than standard or high foc arrows.  I find EFOC arrows are easier to tune.  They are more  forgiving of minor errors in form.  I am shooting mine with four 3 inch fletch.  I find they have far less drift in a cross wind. The four 3 inch fletch also control my broadheads perfectly.  Having shot all levels of FOC I will not be going back to average or high foc arrows.  Standard arrows will kill animals.  EFOC arrows give me the edge I am looking for when an off shot leaves me needing a bit of extra penetration.

+1 ... these are my findings as well.  

nope, no one absolutely needs a high foc or efoc arrow.  10% foc woods/alums/carbons have killed and will continue to kill a ton of game.  always still comes down to accuracy and sharp heads.  

however, for me, an efoc carbon just works *better* and definitely gives me an edge in both accuracy and penetration.  as always, ymmv.

[ishoot4thrills]

Exactly. Well said.

[Terry Green]

Originally posted by Jason R. Wesbrock:
George,

There's probably a good reason why 10-15% FOC has been the norm for hunting arrows for decades. That's not to say EFOC won't work; far from it. A lot of folks kill a lot of animals with it every year, just like a lot of folks have killed a lot of animals with normal FOC for generations. They both work, and to me, one versus the other has always seemed a silly thing for people to argue over.

Proper tuning is the key, which is why I'm glad to see you took that step. I would be willing to bet a paycheck that improperly tuned arrows are the number one reason why some folks think they need cape buffalo setups to shoot through a whitetail deer.

I agree with Jason.  I always wonder how the folks that claim they jumped FOC and magically got better flight....just how did they know???

  Did they have crappy flight before and were just miss tuned???...did they purchase some sort of equipment that actually measured this claim of 'better flight' or did they just want to make the claim so bad they convinced them they just 'saw' better fight from good flight already?

Good flight is good flight is good flight....and it does NOT take E-U- or ZFOC - or what ever the 'acronym of the day is' to get it.

And, its WAY more important to have good flight than any number of FOC between 12 and 30%...and again, you do NOT have to have 30% FOC to have good flight....nor will you be able to jump out of a tall building and EFOC save you, or stop a runaway train, or knock down a scud missle. Claims Claims Claims....that's all you hear from some....but no pics of dead animals...just rambling and parroting.  Sorry, some of this just gets real old....and some folks need to start hunting more and typing less.

Read my tag line....

[Rob DiStefano]

terry ....             :D