7 Steps to Bow Tuning – Part 1
Posted on June 19, 2013
Follow this process and you will find yourself with an efficient and accurate bow that will lend itself to confidence in the field come opening day. Check out the first 4 important steps to bow tuning!
Every archery setup has one thing in common—they all fire a similar projectile. The arrow is the primary building block upon which a tuned setup is created. We need to start here. The arrow must be spined correctly; your arrow must not be too flimsy or too stiff. An improperly spined arrow will never get straight arrow flight. For more about bow tuning, click here.
Step 1: Find Your Arrow
Arrow spine is determined by the length of the shaft, the poundage you are pulling, the weight of your field point or broadhead, and the type of cam that you have on your bow. Every arrow manufacturer puts out some sort of arrow-selection chart. Consult this chart at your archery pro shop or on the manufacturer’s Web site to make sure you have the proper arrow shaft for your setup. The arrow must be able to absorb the energy of the bow without flying erratically downrange. Once you are sure you have the right arrow, you can move on to the bow itself.
Step 2: Adjust the Bow’s Axle-Length
When it comes to the actual tuning or adjustment of the bow’s components, start with the manufacturer’s specifications. Bows are designed to shoot best at certain specs, and these measurements should be verified first. Measure the axle-to-axle length and brace height. You may need to twist or untwist the string and/or cable(s) to get the measurements back to factory spec. This will require pressing the bow in most cases. Trust your pro shop to do this for you if you are not comfortable doing it yourself.
Measure poundage to make sure your bow is capable of peak weight. Even if you do not shoot at max weight, make sure your bow can get there, and make sure it is not excessive either. Improper string and cable lengths can make for too little or too much poundage. If you do not shoot at max weight, crank your limb bolts all the way down, and then back them off the exact same amount. Ensure that the tiller measurement (the distance of the limb, at the limb pocket, to the string) is the same on top and bottom. Once you have verified that your bow is set back to factory specifications, you need to check for proper positioning of the cam(s).
Step #3: Cam Orientation and/or Timing
Cam rotation is often referred to as timing. Depending on your bow, this can be accomplished many ways. With so many different cam types and systems out there, we’ll save the minute details for another article, but the principle is the same, regardless of design. On Binary, true twin cams, or hybrid systems, the top and bottom cams must rotate together or you will not have level nock travel. Single-cam bows need to be timed for optimum speed and nock travel as well; it is a common misconception that they do not. A single cam must not be over- or under-rotated.
Regardless of cam design, upon release, if the nock end of the arrow does not travel in a level plane through the rest and out of the bow, you will not have good flight downrange. Consult your bow’s owner’s manual or see your pro shop to verify that the cam or cams are synched correctly. Most cam types will have marks, holes, or some way to verify this visually. You may need to twist the string and/or cables accordingly to correct the timing back to where it is optimized. Again, have your pro shop do this for you if you have any reservations. Once you have the cam(s) timed, it is good practice to take note of the proper position so you can return them to the exact spot if you have any problems in the future. A Sharpie mark on the cam alongside the limb can save a lot of headache, should an issue arise later or when it is time to change strings.
You will also want to make sure that your cam(s) and/or idler wheel is not leaning to one side. You want them positioned straight up and down. Some archers may argue that a bit of limited lean while the bow is at rest is acceptable as long as it straightens out at full draw. I personally prefer cams with no lean at all, both at rest and at full draw. If yours has some lean, you may need to twist one side of the cable yoke to straighten things out. Again, this will require a press, so trust a pro if you are not confident or lack the proper equipment.
A bow at factory specs and is timed properly will maximize shooting efficiency. It will shoot with the greatest speed and with least amount of noise and vibration. It’s the foundation of a properly tuned bowhunting set up.
We now have a system that is properly timed, at factory specs, and shooting a correctly spined arrow. The remaining adjustments are periphery and will be made primarily with the bow’s rest. We’ll get to that shortly. However, we first must ensure that our arrows are clearing the bow without any obstruction.
Step #4: Eliminate Vane Contact
Most hunters these days are using drop-away or fall-away rests. When properly installed, these rests can provide supreme accuracy, but they must be set-up so that there is no contact with the arrow’s fletching. You also don’t want any contact on the bow’s riser, cable, or cable guard.
Contact can be verified by spraying the back end of an arrow and the vanes with foot powder spray that is available at any drug store. This stuff sticks to the arrow and dries white. It is also easily rubbed off. When fired, it will leave a mark anywhere there is contact. This must be corrected before proceeding.
Sometimes twisting the nock a few degrees will simply solve the problem. The drop or fall of the rest may also need to be timed more precisely by adjusting the length of its pull cord. You want the rest to provide the necessary support to launch the arrow, but you also want it getting out of the way in time for the fletching to clear.
Make sure that you have ruled out any contact before proceeding. Now we can start fine-tuning for good arrow flight.
By Nate Treadwell