Ideally, you should adjust your rest so the arrow lines up perfectly with the forward thrust of the string. There are a few simple ways you can do this accurately.
Bows have gotten much easier to tune since manufacturers figured out what actually causes poor arrow flight. Namely, they have gotten much better at creating the correct nock travel (avoiding side-to-side or up/down variations). Many bows I set up will produce excellent arrow flight from the very first shot.
This column is a step-by-step process of setting up and tuning a bow.
I don't tune as many bows each year as a busy bow shop attendant, but I've tuned enough to know getting started right makes the tuning process a whole lot easier.
Rest and nock set position: The proper left-to-right position of your arrow rest can speed the tuning process. When setting up for a release aid, your nocked arrow should line up perfectly with the forward thrust of the string. If you release with fingers, your arrow should be pointed slightly to the left of square (for right-handed shooters).
There are several ways to go about setting the left-to-right position of your rest. First, you can eyeball it by looking at the arrow, string and cams from behind the arrow, but this method is not very accurate. Second, you can use a commercially produced center-shot adjustment tool. These are accurate but time consuming â€“ and not necessary to get the job done well.
I use a simple method that relies on the stabilizer and bow limbs as reference points. Set the bow down, resting its bottom cam on the floor. Now, look down on it from above while comparing the resting arrow to the stabilizer. Move the rest in or out until the arrow is parallel with the stabilizer (though it may not go right down the center of the stabilizer) and perpendicular (at a 90-degree angle) to the face of the top limb. This is a quick, accurate way to set the bow's rest position.
Release-aid shooters should install a nock point on the string so its lower edge is approximately 1â„8-inch above the center of the bow's cushion plunger hole (where the rest attaches). You will need a T-square to accomplish this measurement. Finger shooters should start 3â„8-inch above center.
Now, adjust the rest vertically until the center of the arrow shaft crosses the very center of the cushion plunger hole. You can do this by simply holding the bow up so the rest is at eye level.
Check fletching clearance: The easiest way to eliminate poor arrow flight caused when one fletching hits the rest and kicks the tail of the arrow off line is to use a drop-away or full-capture rest. I see no good reason to use any other model these days. Finger shooters should stick with shoot-around rests, such as flippers and springies. With a finger release, the arrow flexes as it leaves the bow and often brushes the rest as it passes. Some contact is common with finger-released arrows, but if you keep it slight and use rests that flex out of the way easily, the contact will not greatly disturb the arrow's flight.
You may still need to turn the nocks on your arrows so their fletching straddles the drop-away launcher (cock feather up) or misses the harnesses if the cable guard doesn't produce excellent clearance. You can experiment easily with this simple step.
Ideally, your arrows will leave the bow flying straight, with the nock perfectly following the point, making a perfect hole through paper. Unfortunately, that doesn't always happen. Achieving accuracy with broadheads depends on this kind of bullet-hole arrow flight. To get a snapshot of how your arrows are flying, shoot them (tipped with field points) through a framed piece of freezer paper from a range of about five feet. The tears they make, along with the troubleshooting chart I've included, will tell you what to do next.
Arrow selection: Generally speaking, release-aid shooters will experience different arrow flight with different brands of arrows. I have seen significant changes in the size and direction of paper tears when paper tuning when I switched from one brand to another. If you are really struggling to get a bow to tune, consider heading to the archery shop and experimenting with several different shaft styles. When choosing the correct stiffness, release-aid shooters usually are better off going too stiff than not stiff enough. So, if you are going to err, err on the side of increased stiffness.
Finger shooters will find good arrow flight is also related to shaft selection, but small changes in the stiffness of their arrows can have a big affect on arrow flight. Fortunately, there are a few things you can do to better match bow and shaft without having to buy a dozen new arrows.
Specifically, if your arrows are flying tail left, indicating a weak spine reaction for a right-handed shooter, try one of the following solutions: use a lighter point, try composite inserts (both will make the shaft act stiffer) or reduce your draw weight a few pounds. If your paper tears suggest you need more flexible shafts (tail right for a right-handed shooter), first try a heavier point or increase your draw weight slightly.
Bare-Shaft Tuning for Finger Shooting
If you want to try the proven technique of bare-shaft tuning, first shoot a group using fletched shafts and mark the center. Next, from the same distance, shoot a group using bare shafts (fletching removed) and mark this center. If both groups have essentially the same center, your setup is tuned. However, if the bare shafts plane off line, you'll have to make corrections.
Here is a general guide to the proper corrections. If the bare-shaft group is to the left, try a more flexible shaft, increase point weight or increase your bow poundage. If the bare-shaft group is below, move the nock point down, check fletching contact with the rest and check wheel timing. If the bare-shaft group is to the right, try a stiffer shaft, a lighter point or reduce your draw weight. If the bare-shaft group hits high, check wheel timing or move your nock point up.
Micro-Tuning With Broadheads
Even with considerable attention to detail, there is no guarantee broadhead-tipped hunting arrows will hit the same exact holes as the same arrows carrying field points.
Technically speaking, if your hunting arrows group in a different part of the target from your practice arrows, your bow is not perfectly tuned. Small differences are common, even when the setup paper tunes beautifully. You can pull the groups together easily by simply moving your rest very slightly in the direction required to bring your hunting arrows closer to your practice arrows.
When the broadhead-tipped arrows are impacting to the left of the field point arrows, simply move the rest very slightly to the right. When you're all done, you will probably have to sight in your bow again, but the groups should pull together.
Though it may be an inconvenience if your hunting arrows and practice arrows group differently, it is a much more serious problem when your hunting arrows fail to group at all. This is likely caused by differences between individual arrows, and more specifically, by poorly aligned inserts. If you find yourself looking at arrows scattered all over the target, focus on your arrows first and then go back to worrying about the location of the group.
With patience and attention to detail, you can turn any bow into a well-tuned hunter. Bow tuning is more than just a good idea; it is mandatory if you hope to reach your potential as a bowhunter. Don't be intimidated. It will all make sense once you dive into the project.