How to tune a compound bow

A tuned compound bow launches the arrow straight off the string and rest, nothing touches the arrow on its way out, and every arrow you hunt with hits where you aim at the distances you shoot. For a hunting setup the last part is the test that matters: broadheads and field points landing together at your longest hunting distance.

Tuning is a sequence. Each step assumes the steps before it are right. A rest moved to fix a tear caused by cam lean, or a broadhead offset caused by a vane hitting the rest, leaves the bow worse off than before. This page covers the order, the checks before it and nock tuning. Each tuning method has its own guide.

A tune also depends on the archer. If your shots scatter with the same setup, fix that first; the compound bow form guide covers stance, grip, anchor and release.

Most of the tune can be done at home with:

• Hex wrenches that fit the rest, sight and limb bolts.
• A bow vise or stand that holds the bow vertical.
• A bow square or an arrow level for the nock point.
• A draw weight scale.
• Foot powder spray or dry shampoo for contact checks.
• A paper-tuning frame, and a target that stops bare shafts and takes broadheads.
• For the arrows: a grain scale, an arrow squaring tool and a spin tester.
• A paint pen and a notebook for marks and settings.

Anything that changes the length of the string or cables needs a bow press: twists to bring axle-to-axle length or brace height back to spec, timing the cams, twisting yoke legs, correcting peep rotation, serving in a peep and replacing strings. On many bows, shimming the cams also requires a press. Checking cam timing and cam lean at full draw needs a draw board. Without them, have a pro shop do the bow check and those adjustments, and do the rest of the tune yourself.

Tuning assumes the bow matches its specs. Find the manufacturer's numbers for your model in the owner's manual or on the maker's website and check these first. An out-of-spec bow can still be made to tear a bullet hole, but then the rest is compensating for a problem that will come back.

Draw weight

Check peak draw weight on a scale. Adjust it by turning both limb bolts the same amount, and don't back them out past the limit in the manual. Set your hunting weight before tuning: draw weight changes how the arrow bends at launch, so changing it later means retuning.

Draw length

A draw length that is too long causes form problems that look like tuning problems. Have it checked by a shop or measure it. The release and the D-loop also change where your hand ends up at anchor: a longer loop makes the effective draw longer. Settle the release and loop before judging draw length.

Axle-to-axle length and brace height

Measure axle-to-axle length from the center of one axle to the center of the other, and brace height from the deepest part of the grip to the string. Compare both to spec. Strings and cables stretch and creep with use, which moves these numbers along with draw length, draw weight and cam timing. Twists in a press bring them back.

Cam timing and cam lean

On a bow with two cams, timing means both cams reach their draw stops at the same moment. Out-of-time cams change the path of the nock and can cause vertical tears that moving the nock point won't fix. If you can't correct a high or low tear, have a shop check the timing. Cam lean is a sideways tilt of the cams at full draw caused by uneven cable tension. It produces left-right problems the rest can't correct. Both are checked at full draw and corrected with cable or yoke twists or, on some bows, cam shims. The cam timing guide covers both checks, and the draw cycle explorer shows how the cams turn through the draw.

String and cable condition

Look for frayed or broken strands, loose or separated serving, and a peep that doesn't come back to the same rotation. Worn strings don't hold specs or a tune. Replace them before you tune, not after.

With the bow in spec, put every part of the setup in a known starting position, so the tuning that follows is small adjustments. The compound bow setup guide covers each install step in detail.

Mount everything first

Install everything you will hunt with before you tune: rest, sight, stabilizer, string accessories, and the quiver if you shoot with it attached. Use your hunting release. Every part affects the tune, and from here on you change one thing at a time.

Centershot

Centershot is the left-right position of the arrow relative to the string. Start at the manufacturer's spec, usually given as a distance from the riser to the center of the shaft. Many current bows specify about 13/16″, but it varies by model, so check yours. Without a spec, measure from the riser to the shaft at the front and back of the riser and move the rest until both match. Walkback and broadhead tuning set the final position.

Nock point and arrow level

Clamp the bow vertical, nock an arrow, and rest it on the launcher. Use an arrow level or a bow square to set the nock point so the arrow sits level, square to the string, with the shaft running through the center of the Berger holes. Some archers start the nock slightly above level instead. If your rest's instructions give a starting height, use it. Paper tuning sets the final height.

Drop-away rest timing

A drop-away rest's launcher should be fully up before you reach full draw, stay up long enough to guide the arrow at the start of the shot, and be down before the vanes reach it. Follow the rest maker's timing method; most use timing marks or a draw board. A rest that drops too early can produce a tail-low tear that looks like a nock point problem.

D-loop

Tie the loop above and below the nock with enough space between the knots that they don't pinch the nock at full draw. Nock pinch can lift the arrow off the rest. Loop length changes your effective draw length, so set it and leave it. Retying the loop means rechecking the nock point.

Peep

Set peep height so that when you draw and anchor with your eyes closed, you open them looking through the peep. Serve it in before you shoot: don't draw or shoot until every string accessory is secured. If it comes back turned at full draw once the string has settled, the fix is half twists in the string in a press, not turning the peep.

Arrows

Tune with the arrows you will hunt with: a spine that suits your draw weight, arrow length and point weight, and field points that weigh the same as your broadheads. The arrow setup guide covers choosing them, and the spine chart and Arrow Lab check a build before you cut shafts.

Before shooting paper, make sure nothing touches the arrow on its way out. Spray foot powder or dry shampoo on the launcher and the area around it, the cables and cable guard, and the back of the arrow including the vanes. Shoot one arrow into the target and look for streaks in the powder.

A vane hitting the rest or a cable causes tears and groups that no rest or nock adjustment fixes. Depending on where the mark is, rotate the nock so the vanes pass the launcher and cables cleanly, move the rest slightly, or change the launcher or the vanes. Repeat the check after every fix until the powder comes back clean.

With the bow in spec, the baseline set and no contact, tune in this order. Each method catches something the one before it can't see.

Standard order

Contact check → paper → bare shaft → walkback → nock tuning → broadhead → groups.

Make one change at a time and shoot at least three arrows before judging it. A single arrow can't separate a bow problem from a bad shot.

Paper is the first test of how the arrow leaves the bow. Shoot fletched field-point arrows through a sheet of paper from about 4 to 6 feet and read where the vane cuts sit relative to the point hole. Fix vertical first: a tail-high tear means raise the rest or lower the nock point, and a tail-low tear means the opposite. Then fix left-right tears with small rest moves, about 1/32″ at a time. When the tear is clean, step back a few feet and confirm it holds.

What it catches: nock height, large rest position errors and contact. What it misses: small left-right errors, and spine problems the vanes correct within a few yards. The paper tuning guide covers every tear, and the paper tuning helper gives the adjustment for the tear you shot.

Shoot a few fletched arrows and one or two identical arrows without fletching (same point weight, same nock) at the same mark from 15 to 20 yards. Vanes steer an arrow straight and hide part of a bad launch. A bare shaft has nothing to steer it, so where it lands relative to the fletched group shows how the arrow actually left the bow. Never shoot a broadhead on a bare shaft.

What it catches that paper misses: spine mismatch, cam lean and small nock or rest errors that read as clean at a few feet. The bare-shaft tuning guide explains how to read the impacts and what to adjust.

Hang a vertical line of tape or string on the target with an aiming dot near the top. Aim at the dot with your 20-yard pin from 20 yards, then from 30, 40 and farther, always with the same pin and the sight's bubble level. The arrows land lower as you back up, but they should stay on the line. If they drift left or right as distance grows, the rest's left-right position is off. Move it a small amount, bring the 20-yard arrow back onto the line with the sight's windage, and walk back again.

What it catches that bare shafts miss: left-right rest position errors too small to show at short range. It sets the final centershot for your bow and arrows. The walkback tuning guide has the setup and the adjustments.

The steps so far tune the bow. Nock tuning matches the arrows to it. Even a matched set of shafts often has an arrow or two that lands outside the group. Turning the nock changes which side of the shaft faces the string, and an arrow that misses in one orientation often groups in another. The usual explanation is that a shaft is not equally stiff all the way around. Either way, the test is practical: keep the orientation that groups and set aside the arrows that never do.

When to do it

After paper, bare-shaft and walkback tuning, with field points, and before broadhead tuning. If the bow is still out of tune, every arrow misses for the same reason and the test tells you nothing. Nock tuning doesn't replace any earlier step, and new arrows go through it too.

Prepare the arrows

• Number every arrow on the shaft or the wrap so you can track each one's impacts.
• Weigh them. A set should be within a few grains of each other, ideally no more than 3 grains between the heaviest and lightest. An arrow that is much heavier or lighter will hit high or low however the nock is turned.
• Square the insert ends with a squaring tool so points and broadheads sit straight on the shaft.
• Spin-test each arrow with its field point, and later with its broadhead. Wobble at the tip points to the insert, the point or a bent shaft. Check the nock end as well; a crooked nock shows as wobble at the back.
• Check the hardware. Nocks fully seated and undamaged, vanes glued down along their whole length, and no buzzing when you tap the point lightly on a hard surface. A buzz usually means a loose insert or point.

The procedure

1. Sight in at 20 yards and pick one arrow that has been grouping well as your reference arrow.
2. From 20 to 30 yards, shoot the reference arrow at a small aiming spot. Then shoot each of the other arrows at the same spot, one at a time, pulling each arrow before the next shot.
3. Sort the arrows into those that hit with the reference and those that don't. Shoot the misses again to make sure the miss was the arrow and not the shot.
4. For each arrow that misses twice, rotate the nock one vane position: 120° on a three-vane arrow, 90° on a four-vane arrow. Turning by a full vane spacing keeps the vanes in the same position relative to the rest and cables, so clearance doesn't change. Only the shaft's orientation on the string changes.
5. Shoot it again. If it now hits with the reference, mark the new position, either by marking the new cock vane or with a paint pen index mark on the shaft. If it still misses, rotate to the next position and repeat until you have tried them all.
6. Write down which arrows needed a rotation. When a nock is replaced later, set the new one in the marked position.

Culling flyers

An arrow that misses in every orientation has a problem the nock can't fix. Check it for cracks, a loose or crooked insert, a bent shaft and damaged vanes, and discard a cracked shaft. If you find nothing, use it as a practice arrow, or strip it and refletch with the vanes in the gaps between the old positions, which turns the shaft relative to the vanes, then test it again. Don't hunt with an arrow that won't group.

The bare-shaft version

Some tuners nock tune bare shafts through paper before fletching them: each shaft is turned through several marked positions, shot at close range, and fletched so the arrow nocks in the position that tore the cleanest hole. This needs a tuned bow and correctly spined shafts to start.

With the bow and arrows tuned on field points, shoot a group of field points and a group of broadheads of the same weight at the same mark from 20 yards, then farther. Spin-test every broadhead on its arrow first. If the two groups land apart, the arrow is still leaving the bow at a slight angle, and the broadhead's blades steer it further off line in flight. Fix vertical first: broadheads grouping above the field points means raise the nock point, and below means lower it. Then correct the left-right offset with the rest, or with yoke twists or cam shims if the rest has moved far from centershot.

What it catches that the field-point steps miss: launch errors small enough that field points hide them. Fixed-blade heads show these most. If the groups won't come together after a few rounds of adjustment, the cause is earlier in the order: spine, cam lean or contact. The broadhead tuning guide covers every impact pattern, and the broadhead tuning helper gives the adjustment for the one you shot.

The last check is the whole setup at the distances you hunt. Shoot groups with each hunting arrow and its broadhead at your longest hunting distance. Some archers go further with group tuning, also called micro tuning: shooting groups at long range and changing the nock height or rest position 1/32″ at a time, keeping a change only if the group gets smaller.

Then sight in and build or check your sight tape with the sight tape guide and the sight tape generator. Finally, write down the specs (draw weight, axle-to-axle length, brace height, nock height and centershot), mark the rest's position and the cam positions with a paint pen, and keep the notes with the bow. If something moves later, you can tell what changed.

A tune holds as long as nothing changes. Go back through the order after any of these:

• New string or cables. Shoot them in until they stop moving (see the FAQ below), then check axle-to-axle length, brace height, timing and peep rotation, correct them in a press, and tune.
• A change in draw weight or draw length, including a new draw module, a different release or a new D-loop.
• A new or moved rest, peep or nock point.
• Any arrow change: shaft, length, point or insert weight, vanes, nocks or broadhead model.
• Travel, a fall or a hard knock. Check that the rest, sight and cams haven't moved, then confirm with paper or a walkback and a broadhead group.
• Before the season. Even if nothing changed, check the specs and shoot broadheads at your hunting distances.

Not every change needs the whole sequence. After a peep move, paper and a sight check may be enough. After new strings, start from the bow check.

1. Have draw length checked, and draw weight, axle-to-axle length, brace height and cam timing set to spec (a pro shop, or a press and draw board).
2. Shoot a new bow or new string in before tuning.
3. Mount every accessory you hunt with.
4. Set centershot to spec and the arrow level on the rest.
5. Time the drop-away, tie the D-loop, set and serve the peep.
6. Prepare the arrows: right spine, weighed, squared, spin-tested and numbered, with field points matching broadhead weight.
7. Run the powder contact check.
8. Paper tune at 4 to 6 feet and confirm a few feet back.
9. Bare-shaft tune at 15 to 20 yards.
10. Walkback tune from 20 yards to 40 and beyond.
11. Nock tune the arrows at 20 to 30 yards.
12. Broadhead tune from 20 yards out.
13. Sight in, build the sight tape, and confirm groups at your longest hunting distance.
14. Write down the specs and mark the rest and cams.

• Tuning on a new string before it has settled.
• Skipping the bow check, then using the rest to make up for cams that are out of time or leaning.
• Changing two things at once. You can't tell which one worked.
• Tuning with different arrows, points or a different release than you hunt with.
• Pushing the rest far from centershot to chase a tear or a broadhead offset. When the rest has to move a long way, the cause is usually cam lean, spine or contact.
• Judging a change on one arrow instead of three or more.
• Tuning when tired, or with form that isn't settled.
• Using the sight to cover a broadhead offset before the bow is tuned.
• Not writing settings down, so there is nothing to go back to when something moves.

What order should I tune a compound bow in?

Check the bow against its specs, set the rest, nock point, D-loop and peep, run a contact check, then paper tune, bare-shaft tune, walkback tune, nock tune the arrows, broadhead tune, and finish with groups at your longest hunting distance and a sight tape. Each step assumes the ones before it are right, so a problem found late usually means going back a step.

Can I tune a compound bow at home?

Most of it. Setting the rest and nock point, the contact check, and paper, bare-shaft, walkback, nock and broadhead tuning need only hand tools, an arrow level or bow square, paper and a target. Changing string or cable length (specs, cam timing, peep rotation, yoke twists) needs a bow press, and checking timing needs a draw board. A pro shop can do those steps.

How do I know if my bow is out of tune?

Typical signs: broadheads that no longer hit with field points, a paper tear that has changed since the last session, groups that drift sideways as distance grows, a peep that comes back turned, or axle-to-axle length, brace height or draw weight that no longer match the manufacturer's numbers. Check your form first, since a torqued grip or an inconsistent release produces the same symptoms.

How often should I tune my bow?

Retune when something changes: new strings or cables, draw weight or draw length, the rest, peep or D-loop, the arrows, or after a fall or a trip. Many hunters also check specs and shoot broadheads before each season. A bow that still groups field points and broadheads together doesn't need a retune just because time has passed.

Do I need to do every tuning method?

No. A contact check, paper tuning and broadhead tuning are the minimum for a hunting bow. Bare-shaft and walkback tuning are worth the time when paper looks clean but groups don't, or when broadheads won't come together with field points. Nock tuning is worth it when one or two arrows keep landing outside the group.

Should I tune with field points or broadheads?

Field points for every step up to broadhead tuning, weighing the same as your broadheads. Never shoot a broadhead on an unfletched shaft: its flight is erratic and dangerous.

How long does a new string take to settle?

It depends on the string. Cycling a new bow about 100 times settles the string and cables, and the peep can need another adjustment after a further 150 to 200 shots. After the break-in, check axle-to-axle length, brace height, cam timing and peep alignment, correct them in a press, then tune.

Why does one arrow keep missing the group?

Check that arrow before the bow: weigh it, spin-test it, and look for a cracked shaft, a loose insert, a damaged or crooked nock, and loose or bent vanes. If nothing is wrong, rotate its nock one vane position and shoot it again. If it still misses in every position, make it a practice arrow.

Axle-to-axle

The distance between the centers of the two cam axles. Compared with the manufacturer's spec to check string and cable length.

Brace height

The distance from the deepest part of the grip to the string at rest. Changes as strings and cables stretch.

Cam timing

Whether both cams of a two-cam bow reach their draw stops at the same moment. Checked at full draw on a draw board.

Cam lean

Sideways tilt of a cam at full draw, caused by uneven cable tension. Causes left-right problems the rest can't fix.

Centershot

The left-right position of the arrow relative to the string. Manufacturers give a starting value; walkback and broadhead tuning set the final one.

Berger holes

The threaded holes in the riser above the grip. Used as a reference for setting the arrow's height on the rest.

Drop-away rest

A rest whose launcher is raised by a cord attached to a cable or limb as you draw, and falls away as the shot goes off so the vanes pass without contact.

Nock tuning

Rotating an arrow's nock by one vane position at a time until that arrow hits with the rest of the set, then marking the position.