Clocking your arrows is How to determine what helical to fletch your arrows. It is the way the arrow naturally wants to spin out of the bow.
How to determine what helical to fletch my arrows: Tim Gillingham explained to me years ago how to clock my arrows and how it was part of his arrow builds. I have always been a if it ain’t broke don’t fix it kinda guy but after doing a podcast on super tuning our bow with Chris Dunlap I revisited the idea of doing this. Which sent me down a rabbit hole of testing vanes and variations in helical you can read my findings here. (next week)
Anyway, I found that fletching your arrows the way it naturally wants to spin definitely adds a very slight advantage in arrow performance and if you are the type to want to split hairs then clocking your arrow is the way to go. If you would like to clock your arrow and find out which way your arrow naturally wants to spin out of the bow this is how you do it.
How to clock your arrow: you will need a bare shaft and you must find dynamic spine first because I had one or two arrows that turned right out of a dozen when they were not indexed once I indexed them they all left the bow the same. Most people believe its the twist of your string that dictates which way the arrows will spin out of the bow naturally but i’m not convinced this is 100% true I believe its a number of factors but I haven’t played with it enough to give you a definitive answer however Paige Pearce did a video using same bow two different arrows and they both rotated differently so that plus my experience tells me its not driven by string twist, but I really don’t know what causes the rotation and I don’t care that’s why we check . Lets move on. Once you have an indexed bare shaft mark a line on the shaft that indicates your string position, then get level with a target and move back to about 6 ft and shoot a perfect shot. When you check the arrow you should be able to see the arrow rotated either left or right. The mark its position on the target or take a photo with you phone. then move back in 3ft increments repeating the process until you have made a full rotation. That’s how you clock you arrow. Pretty simple!
So you may be asking why I told you to clock your arrows at 6ft and then 9ft etc. what I found (unfortunately I don’t have an accurate formula) is that arrows than naturally spin faster out of the bow need less helical than others. As a rule of thumb for me if it makes a half rotation by 20ft or less I would go a bit less aggressive on the helical. Well there you have it! That is how I clock my arrows and what I do with the information