Thread: Cam Timing

I have been assuming my Cam timing was 'about right' from the factory.

I came to understand that if I adjusted the weight the bow pulled (poundage, lbs), that the bow should really be tuned again, or at least checked in every aspect.

So as I'd adjusted it down from 62 lbs (max) to about 45 lbs and then yesterday to 50 lbs. I embarked on the tuning process again.

1/. arrow at 90° to string
2/. centre shot checked

3/. Cam timing, this is interesting.

I'd made a draw board, 2x2, pulleys, rope etc. and this made the repeated drawing of the bow, easy.

What I found was that the top cam was hitting the string stop, in advance of the bottom cam. Watching all the youTubery, this meant that I should put turns onto the cable end on the top cam (tighten). Using a portable bow press from eBay.

Then I was getting a large click from both cams when the bow was drawn back by human (me). On examination this was because the cams were at a 3 or 4 degree angle from the cables. I had to then, go and adjust the yoke ends of the cables, to swing the cams back, to line them up with the cables.

Then I thought of something that made a lot of sense to me and is not really portrayed on the youTubery.

If I am measuring the cam timing, when the bow is being held at the pivot point of the hand grip (i.e. where the hand grip, rolls on the thumb/palm intersection) and the string is pulled at the nock point, the string is not being pulled off both cams identically, it is pulling more off the bottom. So the cams are being synced with slightly different amounts of string when the nock point is released. See 1st image.





Then I figured that the bow should be held at the berger hole, when the cams are being synced, so I put a small rope through the berger hole and synced the cams from that stand point, where the string is being pulled off the cams in equal amounts.

When the arrow is released, the fact that my hand is on the hand grip is of no importance once the arrow starts moving, the bow should be figuratively 'sitting still in space' for that briefest of moments, whilst the arrow leaves. Then it is in the interests of accuracy, that the arrow is centred and at right angles is the the string and the bow should pull the same amounts of string from top and bottom to do this.

See 2nd image.






again this stuff is new knowledge to me, I post what I've learned, out of interest.

Maybe it's helpful, to another newbie like me