# understanding basic (bare shaft) tuning



## Joe T (Apr 5, 2003)

Only attempted possibly sensible explanation of how tuning works I've ever come across is this:
Bow Mechanics
:wink:


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## Viper1 (Aug 21, 2003)

fluca -

It's incredibly simple (in theory). An arrow has to bend around the riser as it's shot. For a right handed shooter: If the arrow is too stiff, it doesn't bend enough and hits LEFT, it's it's too weak it bends too much and hits RIGHT. Without fletching to correct for that, the arrow will continue left or right based solely on its dynamic spine. 

The nocking point thing is even simpler. NP position is determined so the VERTICAL forces on the arrow balance. If the nocking point is too high, the forces from the upper limb > from the lower limb and the arrow angles down and vice versa. 

You can find more technical stuff around, but that's it in a nutshell.

Viper1 out.


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## Sanford (Jan 26, 2009)

From the perspective of tuning the bow to the arrow and how/why the shaft bend is utilized, see this article: http://www.archery.org.au/lib/pdf/recurvebowtuning.pdf It's easy at explaining.


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## Joe T (Apr 5, 2003)

As the "usual suspect" stories are appearing maybe a brief comment (simplified but contains the basic elements).

In table tennis if you put top spin on the ball it curves downwards in flight, put back spin on the ball and it curves upward. The effect is not related to how the ball is bending  the curved flight is an aerodynamic effect.

You get a similar aerodynamic effect (though different mechanism) with a rotating arrow. If the arrow is rotating in the sense point down, nock up then the arrow curves downwards and so on for curving up, left or right.

You launch an arrow by pushing it hard at the rear end so it's easy to see why the arrow can leave the bow with a lot of rotation (try balancing a pencil on your finger and pushing up hard).

So an arrow leaving the bow rotating around a vertical axis will curve left/right depending on the rotation direction. The amount the flight curves will depend on the arrow speed of rotation. If you shoot fletched and bare shaft arrows with the same initial launch rotation the fletched arrow rotation rate slows down faster than the bare shaft one which results in the bare shaft curving more in flight and hence hitting further left or right then the fletched arrow. The relative hit positions of the two arrows tell you the rotation direction and the distance between the arrows indicates the amount of launch rotation rotation.

The tuning method re bow adjustment is controlling the launch rotation.

With e.g. paper tuning your directly assessing the rotation direction (tear orientation) and speed of rotation (length of tear).

Suggest downloading the drift program from the link above and simulating the various tuning methods. It's a big help in understanding how they work.


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## jerrytee (Feb 5, 2005)

go to www.wernerbeiter.com/en/informations/videoclips/the_way_to_the_center.php and have a look at the video clips.It shows the arrow flexing as it comes off the bow. Note how the arrow flexes clear of the bow. That is what you are trying to get with a correctly spined arrow and bareshaft tuning will show you that you are getting that.


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## Joe T (Apr 5, 2003)

I don't think the Beiter website videos includes it but on my VCR Way to the Centre (anybody remember VCR?) there is a correct arrow/weak arrow sequential sequence. For anyone with the full monty video well worth studying this sequence. 

Don't confuse arrow selection/flexing with tuning. They are interrelated but not the same thing. You can have the perfect arrow combined with a crap tune. This is sort of obvious else there wouldn't be such a thing as a "tuning method".


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## Inventor T (Sep 2, 2009)

*Vcr*

Is that the old way to spell DVD? ;o) Great info guys!


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## fluca1978 (Jan 26, 2009)

Sanford said:


> From the perspective of tuning the bow to the arrow and how/why the shaft bend is utilized, see this article: http://www.archery.org.au/lib/pdf/recurvebowtuning.pdf It's easy at explaining.


Despite the explaination, that is very clear (as Tapley's one is), this method does not rely on the button berger. So it requires your arrow can fly well without any "dynamic" correction. Interesting...


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