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View Full Version : When is centre shot not TRUE centre shot?



Unregistered
05-13-2008, 09:26 PM
Would love some help on this. I use the word SEEMS when I am not sure...and hope you will reply the same. Please read the entire message carefully before you fire off a reply at half draw.

I have a true centreshot bow (or so it seems). With Cougar4 shoot through (Nitrous) the centre shot (cam to cam) lines up perfectly down the centre of limbs and riser (so it seems, and according to Martin). BUT THE BOW DOESN'T SHOOT CENTRE SHOT AT FULL DRAW.

AT ZERO DRAW
I line up my drawstring and arrow (and rest) with the centre shot line on my bow. Perfect and easy to do on this bow.
Next I line up my pins in a perfect line between drawstring, shaft tip and target centre, sighting down the arrow shaft - everything lined up with the centre shot line of the bow.

BUT....

AT FULL DRAW
I have never ever been able to shoot a bullseye with my pins lined up this way. I shoot to the left of target centre everytime. So I always have to wind my sight pins in towards the riser (to the left of this so called zero draw centre-shot position).

I shoot release aid/prong rest - index vane down through centre of prongs
I shoot perfect arrow specs - perfect grouping, perfect flight.
I shoot near perfect form - the arrows group well tightly enough.

QUESTION
Obviously centre shot pin and arrow alignment at zero draw is different at full draw.
Or is it?
Why do I need to shoot with my pins wound in from this alignment?
Is it limb twist or cam lean? I seem to have zero cam lean on this shoot thru setup, even at full draw. But I noticed there is slight limb twist when sight down the length of each limb.

Please advise if there is anything unusual about the above discovery.

cheers

flytier17
05-14-2008, 04:59 AM
I would say you do havwe cam lean. Here is ow to check.

Lay a straight arrow on the side of the cam, parallel to the string. Observe the gap between the tip of the arrow and the string. Now repeat on the other side of the cam. Compare the distances. This should tell you if there is or is not any lean.

If there is lean, you need to twist the cable that attatches to the tip of the limb that is higher (the side with the most gap between arrow and string). You can do this without a press. Grasp the limb with your hand, and pull the OTHER cable with your fingers toward the riser. This will flex the limb sufficiently that the other cable can be removed. Relax the presure, and give the cable a 1/2 twist tighter. Add the pressure, and replace the cable.

Now do this to the bottom cam.

flytier17
05-14-2008, 05:00 AM
#2, your arrows ay be overspined. Check this with a bareshaft tune.

scepterman30x
05-14-2008, 08:12 AM
I think you are missing the big picture here. Though what you have done is correct. You cannot just eyeball it and assume that is it. Take your arrow for instance; you can line it up perfectly with the riser, limb, rest and have no cam lean and then look at the alighnment of the all these things in relation to the tip of the arrow and notice that it still is not lined up perfectly. Then you have to factor in even if everything lines up perfectly; you have hand torque and other factors that come in to play. I would paper tune, then walk back tune it and not worry about minor trivial details as long as it shoots good.