bigbulls

A fletching jig with a helical (or straight) clamp should be adjusted so that the feather or vane makes 100% contact with the shaft. This is done with the adjustment screws or dials depending on which jig you have. You can get away with a little more if you press the clamp against the shaft while the glue dries.

The ammount of adjustment necesssary is 100% dependant on how "fat" the shaft is. The fatter the shaft the more helical the shaft will take while still maintaining full contact between the shaft and the fletch.

I hope this answers both questions here.

Straightarrow

Bigbulls has it right. If you want to change your helical, you have to change the shaft, or possibly buy a different helical jig that is designed differently. However, even that won't change it a lot. The helical designed into the clamps is appropriate, and nothing to worry about as long as it doesn't interfer with your rest.

Arthur P

You can wrap a helical really tight if you leave the base of the fletch down away from the clamp on both ends, then offset the jig to make the fletch fit. Especially so with a 5-5 1/2" fletch. My idea of too much helical is when you sight straight down the shaft, from the pointy end, and can't see any clearance between the leading end of one fletch and the trailing end of the next one. It's hard - next to impossible - to get that much helical with a 4" or shorter fletch.

mobow

Personally, I don't think you can have overkill as it pertains to helical. The more rotation the better!

Arthur P

Spin and stablization are good things, but only to a point. Consider...

What makes the arrow spin? The air flowing across the surfaces of the fletching. What makes the air flow around the fletching? The arrow's movement. What makes the arrow move? The energy it gets from the bow string. That's the only energy source for the arrow, meaning the arrow has a finite amount of energy when it leaves the bow. Part of the energy it leaves the bow with is being used to make that arrow spin.

Say we shoot identical arrows from the same bow - with identical fletching size and type, one with moderate helical and the other with a very tight helical - the tight helical, rapidly spinning arrow arrow will burn up energy faster during it's downrange flight and it's forward speed will decay faster than than the slower spinning, moderate helical will. To say the same thing another way, the faster the arrow is made to spin, the more energy is used up to cause that spin. The more energy going into making the arrow spin, the less energy is available for the arrow's forward motion, downrange speed and, for a hunter, penetration.

That's not to mention that getting an overly tight helical can actually reduce the fletching's effectiveness by the front ends of the fletching diverting a good portion of the air away from the rear surfaces of the fletching. The fletching begins to act like a parachute instead of guidance surfaces. Along with the excess drag, you get those annoying flapping, hissing and whistling fletching noises.

Also, nowadays most guys are using light, small diameter carbon arrows instead of heavy, large diameter aluminums. Lighter and smaller diameter means the arrow is easier to spin, due to less rotational inertia. Using a 400 gn GoldTip XT and a 530 gn XX75 2315 as examples, it takes less fletching area or less helical, maybe even both, to induce the same rate of spin in the GoldTip as it takes to get the 2315 going.

I wish I could remember where and when I read the article, but I can't... It was the published results of wind tunnel testing on just about every fletching configuration you could think of.

Straightarrow

Arthur, I never considered not seating the fletch in the jig. Good tip - thanks!

mobow

Ok. I think I understand. Air flow around the fletching is what causes the rotation, so the more rotation, the more air flow (wind resistance) which is what causes the arrow to not only stabilize, but to slow down. Yes? This is the same reason feathers stabilize better than plastic, because of the wind resistance, which is why feathers lose speed down range as compared to plastic.
You make perfect sense here, and I see your point. But, to the average bowhunter who takes shots at 30 yards or closer, the speed will not have decreased by much, correct? Now, if you are a target shooter, who shoots at lets say 50 or 60 yards, I can see where the fall off in speed might make a problem.
So, if I understand correctly, more spin equals = more stabilization = better broadhead flight. But, it's not losing energy stored from the bow, I don't think. Yes, the arrow gets its energy from the bow, but the bow is not causing the spin, the air flow around the fletching is. So I could see that the wind resistance would slow the arrow down, but not that the spin is eating up energy it got from the bow. I don't know, maybe it's basically the same thing. Not arguing or trying to be disrespectful in any way, just really interested in this topic.
Or am I completely off base here, which is most certainly possible.

Arthur P

I think you've got a glimmer of enlightenment, but have yet to step into the full blaze of illumination there, mobo.

Ever heard of flu-flu fletching? It's used for aerial shooting, to severely cut the distance an arrow will travel when shot into the air. Where a normally fletched arrow would fly a couple hundred yards, a flu-flu will only go about 45-50 yards before the fletching robs the arrow of all it's energy and makes it fall out of the air. There are several ways to make a flu-flu, but one is to use a long, uncut feather and spiral it tightly around the shaft.



That is an extreme example of how too much helical causes the arrow to lose energy faster. A flu-flu arrow is stable and accurate. It straightens out quickly when it leaves the bow. It uses up energy so fast that it can't stay in the air very long, but that's the whole idea behind it.

You're correct that an arrow won't lose as much energy within 30 yards as it would at longer distances, but that's not really the point. You can reach a point with helical where any more doesn't increase the spin of the arrow. Instead, it begins acting like a flu-flu and causes the arrow to lose speed and energy faster than need be.

The trick with helical, or even offset, is to figure out how much will give you the best stability and accuracy while limiting how much speed and energy the fletching will bleed off the arrow downrange.

There is some good info on fletching styles at www.trueflightfeathers.com

mobow

The light just came on! I got it now. So no matter how much helical you put on, there comes a point where the arrow won't spin any more, just slow down. Makes perfect sense. Thanks for the edumacation!