Right or left helical ?

[pokynojoe]

PRB wrote:

"Im not sure if anyone uses helical on theyre bolts or not. I have a straight clamp. I really should have asked in reference to right or left hand offset and/or degrees.
Does anyone out there use helical ?"

I stand rebuked. Nevermind, I guess I was thinking "traditional" archery.

Thanks PRB. I just got a little confused there.

Regards
Joe

[pokynojoe]

GaryL wrote:


"pokeynojoe I do not know of any that use a TRUE helical fletching on a xbow, however that being stated one could, as long as you did not put too much twist (helical) on the feather as to rub the rail. With feathers I have been told one can go 4deg. helical but have not tried that."

Seems like that would be counterproductive in a crossbow bolt. Helical fletching provides greater spin, greater spin means more drag, more air resistance means slower arrow/bolt; ergo more trajectory, which means greater range estimation. I would think in a crossbow (in particular a hunting crossbow) the goal would be flatter trajectory, ergo more speed. But like I said before, I'm relatively new at this, so feel free to educate me.

Regards
Joe

[GaryL]

pokynojoe wabi or bstout could shed more light on the matter of helical use with a xbow then I can. I myself use the Arizona fletcher which use a offset for the vanes/feathers. I use 4deg. offset with feathers.

[htoler]

I think that you will find that even crossbow bolts have a few degrees of right offset , I believe you cannot go much more than 4 degrees, or the vane will rub / not fight right into the flight rail..

[BUCKSHOT]

Just a thought here, I believe there may be a bit of a misconception .

To use the word helical may not truly be appropriate, the offset is a term used to determine how far the vane centerline is skewed from the centerline of the bolt, it may appear helical because the vane will follow the curvature of the bolt, but in fact the vane will be glued on straight.

I would say that many Traditional Archers would use Helical Fletching for a couple of different reasons, one being that Feathers are more forgiving than plastic and they deflect better when they go over the arrow rest.
The other would be that because the arrows are so long and heavy, it is an advantage to employ Helical fletching to get the arrow spinning sooner during flight than it would with straight fletching.

Why we use helical OR offset fletching on arrows in general.
(quote Trueflight)

Should I use straight, offset or helical fletching clamps?


We strongly recommend offset or helical fletching on all arrows.
Offset or helical fletching causes the arrow to rotate in flight just like the rifling in a gun barrel causes bullet to rotate. This is extremely important. The rotation acts like a gyroscope to stabilize the arrow. This rotation also "averages out" any slight microscopic imperfections in the arrow.

This advantage was reportedly first noticed in smooth bore muskets, shooting round lead balls. The smooth bores were accurate to about 50 yards. However simply adding rifling to the barrel (or even angled scratches inside the barrel!) caused accuracy to improve enough so that the accurate range became 150 yards. This increase was apparent even when shooting the same round lead balls.

Helical fletching offers more stability than a simple offset and is therefore the first choice for any arrow tipped with a broadhead.
(end Quote)

I believe the same theory is applicable to crossbow bolts as far as offset goes, particularly, because (as Gary said) they need to run through the rail track, they are not as forgiving as feathers. generally a straight offset is used to control your arrow flight behaviour and accuracy. I believe the advantages far outweigh the loss of speed due the arrow spinning.

Here are some pictures for you!




I hope some of this helps!

BTW Hey Randy!

[curmudgeon]

I always used right wing clamp on my bitz fletching jig from my vertical bow days, recurve and compound. When I went to making xbow bolts I still use this clamp but I backed off to the least amount of right wing helical that I could use. Right wing gives your arrow/bolt spin to the right which tightens the shaft into the broadhead.
I'm not saying this is best with the 4 inch vanes that I use , it may cause some drag inside the xbow rail and it may slow the arrow down a bit. Still I like the improved accuracy of a spinning shaft, for a longer shot.
I never could understand the degrees of offset and what that does for you.
Looks to me like that would still give you a small rate of spin to stablize your arrow/bolt.

[GaryL]

Super post BUCKSHOT thanks. The drawings are great.

[PRB]

Great post Buckshot I'll put that one on my favorites list.
Thanks for all the replies.

[widowman]

Just a few thoughts.

Both helical and straight fletching can be offset. However, due to the narrow gap of the rail, helical feathers are not a good choice with crossbows; off set fletching is the norm.

You can offset either left or right.

Right or left offset should not have an effect on accuracy.

However, right offset has an advantage of tightening tips.

Otherwise there is no difference between the two.

[hikerman]

thanks for that great post Buckshot !!
Drawings are always easier to understand

Does a counter clockwise or clockwise make a differance for the bolt
tightening up on the brode head on inpack ?

[Don]

I tried Helical from a bitzenburger clamp, had a hard time getting them so as not to touch the rail, and have them all just right so the arrow didn't fly like, cow dung.
I have mine now with straight clamp set at about a 4-5 degree offset and they fly real nice, except for last weekend, see the post on the Seaway Challenge if you want some clarification on that one.
Our resident 3D expert BJ has a jig with I believe about a 7 degree straight offset that fly like, well an arrow. Very, very nice bolts but when you live as far as I do and have to refletched bolts about once every other day for the next archery shoot in the summer, postage can be a little costly. So I work with what I got.
But boy do I wish BJ lived driving distance cause those bolts are sweet.

Don

[ComfyBear]

Don, you're quite correct. I use a jig which has an approx. 7% RW offset and it makes my bolts spin and fly straight and true. I'd go as far as to state that with the proper head in front, and a good shooter behind these bolts, it's possible to hit the dimple on a pimple of a flea's left ball.

Last year I managed to decapitate a grouse at 32 yards.

[LoneWolf]

Last year I managed to decapitate a grouse at 32 yards.

Now that's a picture/shot I would have liked to see...

Got a picture?.... A picture speaks for itself...

Yep, the Gold Tip Laser II's with 7 degree off-set 4" vanes shoot like darts out to 50 yards. (for 3-D of course)

I go with the Right Wing off-set to.

[koni20]

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[Big John]

Don:

I agree with the 7 deg. offset on four in Vanes. BJ is the one who made the Bolts for me in the Target practice thread. They fly like darts. Dead straight out to 35 yds for sure. Next time out they will be forty yd. practice.
In fact it's time to re-order another dozen me thinks.

Very good thread again.

John