By Joe Bell
Every year it seems we’re pummeled with new technology designed to improve bow performance, broadhead accuracy, and arrow speed. All of these things are blessings come hunting season. And archery engineers know this, which is why they’re on a continual reinvent-and-tweak process to enhance the shooting process. The problem is, this new gear is often dialed-in to perfection in a controlled lab setting, where experts can place small touches to make it perform at peak levels.
A new bow is a prime example. Chances are, this year’s bow was made slightly better than last year’s in terms of speed, consistency, and low vibration. However, can this performance be detected and felt straight out of the box, or do you need to create the perfect shooting package by fine-tuning draw length, accessory setup, and cam position to achieve the highest level of precision? Based on my 30 years of shooting compound bows, I believe the latter to be absolutely true.
With that in mind, let’s look at the primary areas of concern when super-tuning a bow. By learning these skills, and by acquiring a few useful tools, you’ll surely up the ante in your shooting game, just like the pros do. And instead of rushing back and forth to your local archery dealer to request these critical alterations, you can do them conveniently at home, to your perfection, even days before a hunt.
As a technical-archery aficionado, I put a lot of tuning focus on the main platform — the bow. The cams must be in proper vertical alignment and synchronization to ensure level nock travel and a smooth arrow take-off. If not, arrow flight and broadhead accuracy will suffer. The system will also emit more noise and vibration, since bowstring travel will veer outside of a straight, consistent line, directly behind the arrow’s nock.
In a perfect world, cam adjustments would be simple. You would draw your bow back, have a friend eye-up which cam’s draw-stop hits before the other, and then place the bow in a press to twist up cables so the cams become synchronized — then you’re done. However, this rarely works as planned. Instead, once the buss cable is twisted, especially in a half twist, the harness tends to elongate and resettle after several shots, causing the dreaded desynchronization to occur again. This back-and-forth process of drawing the bow and placing it in the press for string adjustments continues over and over again, producing less-than-stellar results.
A better way is to use a draw board to synchronize the cams’ stops. This allows for an up-close and meticulous evaluation (while the bow is at full draw) of the orientation of the buss cable against the draw-stops, so you can make your adjustments ultra-precise…no more guessing and drawing back repeatedly. A draw board is also helpful for adjusting the pull-down cord on arrow rests, by ensuring the correct alignment and tension of the cord as recommended by the manufacturer.
Perhaps the greatest virtue in using a draw board is that it simplifies the process of yoke-tuning. Ideally, cam lean is measured dynamically — at the full-draw position. To correct cam lean, use two small levels; one on the bow riser, and another on the cam. Place the bow in the draw board, plum the bow riser using a level, then attach a level to the top cam.
If the cam’s bottom lobe is pitched to the left, causing the bowstring to be left of the centershot position, make one full twist to the left side of the split-yoke harness. Make one twist at a time until the cam position is straight up and down, or plumb with the bow riser’s level. I use a Hamskea Third-Axis Leveling device on the riser, and another hands-free level for the bow’s cam.
Leveling The Sight
Setting the 2nd and 3rd-axis leveling feature on your bowsight will improve shooting form and precision in the deer woods, especially when bowhunting mountain game like mule deer and elk.
To adjust 2nd axis, I place the bow in a vise, position it in a normal up-and-down position, and plumb the riser using a leveling device. The Hamskea device works well for this, too. Then I adjust the sight’s bubble level to center (the 2nd-axis feature).
For 3rd axis, I follow a three-step process. I place a plumb line on a nearby wall, or use a vertically level door jam. Then I place the bow in a draw-board device, but position the device at a sharp, downward angle. I attach the Hamskea Leveling Tool to the bow’s sight bar, or the riser, and align the tool’s dual-bead, four-inch-long sighting pin along the plumb line.
If the sight’s bubble reads out of center while in this downward position, use the sight’s 3rd-axis adjustment (which moves the sight or leveling aperture in and out like a swinging door from the shooter’s face) to re-center it. As a last step, I remove the bow from the draw board and then perform the procedure again by drawing the bow by hand and aligning the Hamskea’s aiming guide to the wall’s plum line. Sometimes, a shooter’s form will alter the level reading, and minor adjustments may be necessary to recalibrate the bubble.
Arrow Flight & Tuning Tips
There are a number of tuning techniques one can use to establish improved arrow flight and broadhead consistency. However, paper-tuning is the foremost choice, since it provides an immediate visual of the arrow’s flight pattern.
I prefer to paper-tune first without fletching attached to the arrow, as it produces the smallest footprint and thus improves tuning precision. I wrap a strip of electrical tape around the portion where fletching would exist. This keeps the arrow properly balanced and weighted. I then shoot this arrow through taut painter’s paper from four to six feet away. Once I have a bullet-like hole, I follow-up with a fletched shaft to confirm the tear. If I don’t see a clean “rip,” then I know fletching contact with the rest is occurring, and I’ll spray aerosol foot powder on the vanes, checking for contact points with the arrow rest. I’ll twist the arrow nock to mitigate this contact, or switch to lower-profile vanes to altogether solve the issue.
If, for some reason, I cannot achieve a precise arrow tear, despite adjusting the arrow rest’s height and centershot position, then I’ll attempt to yoke-tune the bow’s cam positioning.
Yoke-tuning entails placing the bow in a press, then twisting one side of the string harness that attaches to the top limb, or top and bottom limbs (depending on your bow model), allowing you to control the cam(s) vertical positioning and, ultimately, how the bow cycles the arrow. In order to maintain the synchronization of the cams’ draw-stops and the bow’s draw length, you must twist one side of the harness and then untwist the other side in equal rotation.
To perform yoke-tuning, be sure to make one twist at a time until achieving the perfect paper tear. With consistent left tears, twist the left side of the yoke and untwist the right. Continue in this fashion until the tear is corrected. With right tears, twist the right side of the yoke and untwist the left side.
Despite persistent yoke and paper-tuning, sometimes broadheads will still impact a few inches away from fieldpoints at 30 or 40 yards. If this is the case, then you can continue yoke-tuning until the groups align. For example, if the broadheads group left of fieldpoints, then you’d twist the left side of the yoke and untwist the right. If your bow is equipped with a top and bottom yoke, you would make one twist on the left side of each opposing harness, then untwist the right-side portions. By doing this, and then shooting another group, you can actually induce a slight amount of cam lean into the system in an attempt to bring the two groups together. A small amount of cam lean is not always a bad thing!
If you reach a shooting juncture where impact points of broadheads and fieldpoints are only an inch or two apart, you can try adjusting the arrow rest’s position in 1⁄32-inch gaps until the arrow groups intersect.
Bow tuning, for most, may seem like a monumental hassle. However, it’s no different than anything else in life. By doing a little bit of work at the front end of things, you’ll reap improved benefits when it’s all said and done. Besides, sweetening up the accuracy output of your bow can be a big confidence booster come hunting season, making you deadly as a bowhunter.