By "GRIV" George Ryals IV
Here is a blurb that I wrote in another thread and it basically describes
creep tuning and why it works and why it is needed.
Nock travel has three factors, the measured center of the bow and the shooting center of the bow (plane of the arrow’s flight), and the shape of the cam systems. If your two cam bow is timed around the measured center of the bow and you shoot the bow through the measured center you will have level nock travel. The problem is you can’t really shoot an arrow effectively out of the measured center of the bow and hold the bow at the measured center. You could just hold it below the measured center and shoot the arrow out of the middle. This balance condition makes it very hard to aim as steady as possible and they do not recover well from muscle tremors. In my opinion, those handles that are all sight window are not a good design.
The best method is to design the bow with great balance by setting the measured center of the bow between where you hold it and where the arrow flies through it. This creates a well balanced symmetrical riser design that works with the shooter and is very easy to control and the arrow is as close to the measured center as possible. Then when you Creep Tune your two cam bow, you will set up the nock travel to be behind the shooting center of the bow rather than the measured center. Usually this will cause the top cam to be a half twist advanced because the shooting center of the bow is ¼” above the measured center.
Creep Tuning will automatically set your cam timing to the shooting center of the bow and give you the optimum nock travel condition. Creep Tuning is designed for Dual Cam Systems. However if your single cam system or Hybrid System has the straight and level travel that it says it has, you will get optimum results when the bow is tested. If not, Nock travel is present, and there are few options to adjust them to straighten it out.
For those of you unfamiliar with Creep Tuning, here is a little review.
The Creep Tune Procedure
The Creep Tune procedure is as follows:
1. Set the timing as close as you can by eye (you don't have put a micrometer on it; just get as close as you can)
2. Sight your bow in at twenty yards.
3. Put a piece of masking tape on your target butt horizontally. In a pinch, you can use the top edge of a target face.
4. Pull your bow into the wall as hard as you can and shoot arrow #1 at the tape.
On the next shot, creep forward to the front of the valley and shoot arrow #2 at the tape. You make need to re-shoot these shots a couple of times to rule out bad shots.
5. If your bow is in perfect time, both arrows will hit the tape or they will land on the same horizontal plane. (Level with the tape or on the tape)
If the "creep" shot hits HIGH, TIGHTEN or SHORTEN the cable that connects to the BOTTOM cam.
If the "creep" shot hits LOW, TIGHTEN or SHORTEN the cable that connects to the TOP cam.
Make very small, one or two turn, adjustments a time. A little twist goes a long way. You can fine-tune your timing by repeating the test at forty yards. If you make an adjustment at this distance do not turn your cable more that a half a turn at a time. Too much adjustment at this distance can send an arrow over the target butt or in the dirt. When you have completed the test, your bow will be in perfect time, and given that your other accessories are adjusted properly, your bow is as accurate as it can possibly be.
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