Bow-Tuning Basics: How to Set Up a Compound Hunting Bow

For bow geeks, setting up and tuning a compound is almost as much fun as shooting it. Then there's the satisfaction that comes from shooting a good buck with a rig you put together yourself. Much of the work can be done in a garage or home shop, without a press, but it's a good idea to have a local bow pro on speed dial for recommendations, advice, or to tackle any jobs you can't. In my part of Central New York, that guy is Dave White of White's Archery Shop. Dave's been messing with sticks and strings for more than 30 years and takes an engineer's approach to archery. We spent a weekend this spring building and tuning a new bow until it drove tacks. Every bow is different, of course, and may require a specialized tune, but this rough guide will get you started in the right direction.

Whether you’re starting with a new bow, or you just put fresh strings and cables on an old shooter, it’s best to check the specs – yours and the bow’s. First, find or confirm your draw length with this simple calculation. Measure your wing span with your arms stretched out, from the tips of your middle fingers, then divide that number by 2.5. So, if your arms run 70 inches, divided by 2.5, that’s a 28-inch draw.

Make sure the bow is at the factory-specified measurements by tightening draw weight to the max poundage. Dave marks the tiller bolts with a pencil, so he has a visual guide if you back the weight off later on. Next, measure the axle-to-axle length by running a tape measure from the top cam’s axle pin to the bottom cam pin. A 32-inch bow should measure within 1/8-inch of 32 inches. Most new bows will be bang-on, but if your rig is off, get a press, or to a bow shop, and twist or untwist the cables till it’s perfect. Twists will shorten the axle-to-axle. Taking off twists will lengthen it. Finally, check the brace height by measuring from the deepest part of the bow’s grip to the string. If it’s off, add or remove twists from the string.

Most bows have marks on the cam(s) to ensure the timing is correct. They vary by manufacturer, but typically they’re dots or hashmarks that the cables will pass directly between if the cams are timed. If the cable looks off the marks, you may have a timing issue. Confirm this on a draw board or by checking the timing marks while a friend draws the bow. The cams should roll off peak draw weight into the valley at the exact same time. If there are draw stops on the top and bottom cams, make sure they touch the cable or limbs in unison. Bow makers have timing down cold, so it’s rare for them to ship whacked out. But if your bow does have a timing issue, take it back to the place of purchase and have them fix it.

Bolt the rest to the bow, nock an arrow, level it, and eyeball the whole thing so the arrow is running straight parallel to the flat side of the riser. Centershot is slightly different for every bow model but 13/16- or 7/8-inch from the riser is a good place to start. Paper tuning (step 10, below) will ensure its bang-on. Dave likes to laser tune the rest at this stage. Cisno Archery sells a laser aligner for less than $40, but he's partial to the pricier EZE Center LTA tool.

If you’re shooting a drop away, you’ll likely have to tie, serve or clamp the rest cord to the downward buss cable. The key is to make sure it goes into full capture position within the last couple inches of the draw cycle.

Ensure the bow is leveled in a vise, nock and arrow, and make sure the arrow and string are level, too. String levels come in handy here and elsewhere. Some bows like a nearly level knocking point. Other's like 1/16- to 1/8-inch high or higher nocking point. Research your bow's make and model online for the best place to start. But don't lose sleep over this step, because paper tuning will dial it all in.

Start by bolting the sight to the riser, then secure your bow in a vise or to a workbench with clamps. The RAM Micro Adjust is the best bow vise out there, according to Dave, but the Apple Economy Bow Vise will do the job for less money, though its slower to get a perfect level.

Next, use a carpenter's level and your string levels to ensure the rig is dead straight. If the bow sight bubble is now level, then your second axis on the sight is good. If not, check the manual that came with your sight. It will tell you where to find the first, second, and third axis adjustments. The first axis is the up/down tilt of the scope or circular housing around the pins. The second axis is the left/right tilt as indicated by the bubble on the sight. For the third axis, imagine that the pins are on a door hinge—they can swing toward or away from the shooter. The easiest way to check the third access is with the Hamskea Easy Third Axis Level.

Ensuring the right peep height is as important as tying a good knot. The fastest way to find the correct height is to draw the bow with your eyes closed, find your anchor point, then open your eyes. Have a friend mark the string at eye level and start there. When the peep is in, don’t serve it right away. Shoot the bow for a bit and adjust it up and down till it feels right.

Arrow manufacturers list arrows by spine, or the stiffness of the shaft. Slower bows impart less flex on an arrow, so they need less rigidity, or spine, to fly true. Faster bows need a stiffer spine. Arrow manufactures all have calculators on their website to determine the correct spine. Third-party software like Archer's Advantage is also popular with pro shops and hardcore shooters. Factory-fletched arrows work well in most hunting situations, but there's a pleasure in building your own arrows, for sure. I'm partial to helical fletchings and the Arizona Rim E-Z Fletch makes this, well, easy. Likewise, common 100-grain broadheads do the job in most hunting situations, but I'm partial to 125-grain or more. Wherever you land, make sure to weigh and spin-test all your arrows. Toss out any that spin erratically or deviate by more than 10 grains. Number each arrow with a pen on the fletching. That way if you have an inconsistent flyer you can easily identify it, and not take it into the woods.

Congratulations. You bow and arrows are built. Now it’s time to tune. Paper tuning can overwhelm new shooters, but it really isn’t that hard. The most important thing is to get a consistent release with each test arrow.

Start by shooting your new setup at 10 yards. Adjust the sight so it’s dead nuts left to right, but a little high. Step back to 20 and shoot a group, then do the same thing at 30 yards and 40 yards and keep going to your max practice yardage. If you're shooting multiple pins, adjust the elevation of each pin as you move back. Our Hunting Editor Will Brantley recommends three-shot groups opposed to five, which helps take fatigue out of the equation. He also only sights in one range per shooting session, to further cut back on fatigue. That’s darn good advice, but if you’re shooting a single pin slider, check out your sight manual as you’ll probably skip the middle distances and shoot at 20 and 60 yards to select a sight tape.

To ensure your broadheads fly true, you’ll need to walk back tune. I usually do this after a few weeks of shooting the new rig, so I have time to get comfortable with it. Walk-back tuning will help micro-adjust your rest and sight to broadhead flight. Here’s how to do it:

Dialed-in and ready to hunt, now is the time to practice. All the tuning in the world won’t make up for poor shooting form, so get out there and punch some targets.