Cam timing is one of those critical aspects of compound bow tuning that every archer should know. It could be the evil demon that’s responsible for those seemingly unexplained fliers you’re seeing from time to time while shooting your bow.
Cams are the workforce regulators of your bow. They control the string and cable(s), which all combine to get you to your bow’s peak draw weight at some point early in the draw cycle, and then drastically reduce that weight by 60-90 percent by the time you reach full draw.
If you have a two-cam bow, it’s critical that both cams roll over in sync with one another. If one reaches full rotation before the other, then your pull at full draw will be uneven. Cams have stops built into them, which are designed to hit a cable or limb when the cam reaches its full rotation. They “stop” the draw cycle at the appropriate point.
Imagine one cam reaching the draw stop before the other. Releasing from that point, one cam would rotate more than the other in sending the arrow down range. That’s going to affect the string’s interface with the arrow.
When you paper tune your bow, cams that are out of sync can cause tears that are unfixable by adjusting the arrow rest or nocking point. Fix the cam timing, and those holes should become perfect – assuming the arrow spine is correct for a given bow, and assuming the archer’s shooting form is solid.
Same goes for single-cam bows. It’s a myth that cam timing isn’t important on these bows. Manufacturers intend for their single cams to rotate a certain amount, from a specific starting point. If that rotation is off, then the cam’s performance will be off.
Single-cam bows usually have a timing mark that will let you see if the cam is properly timed. Often, it’s a hole in the cam. When the cam is timed properly, you should be able to look through the hole in the cam and see the cable perfectly centered in it.
So how can you check the timing on your dual-cam bows? An easy way is to have a friend watch you draw and play close attention to the draw stops to see when they hit. This is somewhat imprecise, however, and it could be difficult to detect small differences in timing.
A better way to check is to use a draw board. This is a mechanical device that you set your bow on, so you can draw with a mechanical crank. With a draw board, you can slow the draw rate at full draw to closely inspect exactly when each draw stop hits home.
How do you fix timing issues? On a single-cam bow, you twist or untwist the cable on the cam until the cable sits properly in relation to the timing mark.
On dual cam bows, put twists in to the cable connected to the cam that hits the draw stop first. You can put in half twists or full twists to adjust the timing. Start out with small adjustments to figure out exactly what’s needed. Go back to the draw board after each adjustment to check your progress.