Single Cam system and timing. (getting geeky)
I noticed while my daughter was drawing her bow a slight wavering of the nock , and asked her if perhaps the draw weight was too high because when was dot drawing straight back. She replied that if anything she felt she could use a few MORE pounds. This got me to thinking about the nature of a single cam arrangement. I'm trying to understand the mechanical function (or dysfunction) of a single cam and Idler wheel arrangement as is utilized on y daughters' Tigress (Dyna Cam)
It would seem the me, from basic mechanical reasoning, that with a cam (not round) at one end and a round cam on the other end, the nock point will not (can not) stay in the same plane through it's draw cycle and ultimately in the release cycle, since the string is not being un-spooled and then taken back up, upon release, at the same rate at the opposite ends. This would actually induce a up and down oscillation of the arrow before it even clears the rest. Isnít this the very reason that Cam Timing is of such vital importance, since correct cam timing is where the cams work precisely together, and if they are not, this causes the nocking point to rise and fall as the arrow leaves the bow.
What am I missing here?
You are missing nothing; you have hit the nail right on the head. its called nock travel. That and cam/idler lean are why I prefer Dualcams, and do not shoot solos any more.
Creep tuning helps get rid of some of that though.
Can you explain creep tuning in a little more detail flyer17 Im not familiar with that term, Thanks
Well, it involves shooting arrows @ 20yds. you shoot 3 groups. The first, you let yourself creep away from the valley into the ramp-up to peak weight, the secong group you hold steady at the wall, and the third group you pull into the wall. The groups should impact seperately. The goal is to get them to impact all the same, in one big group. This is accomplished by adjusting limb bolts (tillers), and rotating the cam slightly. When the groups are the same, you move out to 30, and 40 if you are a good shot.
When your bow is creep tuned, you have essentialy made it more forgiving to your inconsistency at holding to the wall. In addition, it optmises the cam rotation for the best poerformance with the least nock travel. When the vertical impact is the same, the arrow is being released at a consistent point or nock level. While this does not make the entire nock travel level, it flattens out the nock travel at the beginning, and also finds the best rotation for the least noch travel throughout the rest of the shot.
See here for more info: http://www.spot-hogg.com/newsletter10.shtml