The axis of bow accuracy

The red circle indicates the adjustment screws used to adjust the second and third axes on your bow’s sight.

Level three axes on your bow’s sight or risk misses on longer, angled shots at deer

Properly setting up a modern compound bow is a detail-oriented and often-tedious process. In order to obtain maximum accuracy, many hours of setup and tweaking are required.

While today’s archers are much more knowledgeable when it comes to tuning their bow for perfect arrow flight, many still don’t realize how critical it is to properly level all three axes of their bow’s sight. Failure to do so can result in severe misses, especially when shooting at longer distances or at steep angles uphill or downhill.

An axis is an imaginary line around which an object rotates. A compound bow’s sight has three axes. It is critical that all three are leveled to obtain the most accuracy possible.

The first axis

The first axis is best described as a line parallel to the ground running from left to right in front of the bow This is the least-important axis. This axis is set from the factory on many sights; however, sights that use a scope aperture mounted on a sliding or threaded rod will require this axis to be leveled. Rotate the scope aperture towards or away from you until its face is parallel to the bow’s string.

The second axis

A bow sight has three axes that must be leveled before the bow will shoot true in all situations.

The second axis refers to the level of the sight head and the pins. The simplest explanation of this axis is that it runs through the archer’s line of sight and rotates like the hands of a clock. This is the axis archers spend the most time leveling, and is definitely the most important. Failure to properly set the second axis will cause the archer to cant the bow when leveling the sight level. This will cause the pins to run diagonally, which will cause arrows to hit left or right of the target at longer distances.  This problem will worsen progressively as the distance of the shot increases. Most of today’s better sights offer some type of second axis adjustability. Even if your bow’s sight doesn’t have an adjustment for the second axis, this can be adjusted by shimming the sight mounting bracket itself.

The third axis

The most-misunderstood and overlooked axis is the third axis. This axis runs top to bottom through the head of the sight, perpendicular to the ground.  Picturing the sight head as a door hinge, opening and closing away from and towards the archer, provides the best analogy for the rotation along the third axis. When taking uphill or downhill shots at angles of 45 degrees or greater and distances longer than 20 yards, this adjustment is absolutely critical to avoid left or right misses. This can make a difference of nearly a foot in windage at 50 yards or a steep angle. Most high-end sights offer third axis adjustability, and I wouldn’t purchase one that doesn’t.

To properly level the sight’s third axis, make sure to level the second axis beforehand. The bow should then be placed in a bow vise. Next, install a temporary level on the bow’s riser and level it to match the sight’s level. The bow should then be rotated forward while keeping the temporary riser level’s bubble centered. If the third axis is not properly adjusted, the sight’s level bubble will run off to one side as the angle increases. Adjust the third axis until both the sight level and riser level are centered all the way until the bow’s riser is parallel to the ground. Achieving this usually requires trial and error and several adjustments.

The next step

Once your bow is properly tuned and all three axes of your sight are properly leveled, the bow is ready to be sighted in.  Many times, properly tuned bows that inexplicably shoot to the left or right have sights that weren’t properly leveled to begin with.

I hope this explanation of why and how to level sight axes helps some archers who are struggling to dial in their bows. This can be a complicated and somewhat intimidating process, and if you aren’t comfortable doing it yourself, as always I recommend bringing your bow to a pro shop that offers this service. Most pro shops offer sight-leveling for a reasonable fee, and they can save valuable time by doing it quickly and properly. Whether you’re not sure if your sight is leveled, or if you know it isn’t, have this done today to get the most from your bow setup.

Sammy Romano
About Sammy Romano 32 Articles
Sammy Romano is a lifelong hunter who has worked in the archery industry for more than 24 years. His expertise includes compounds and crossbows. He can be reached at samboka31@aol.com.