Mystery Compound Bow Tune

February 23rd, 2009 / Posted by edersbow.com
Mystery Compound Bow Tune

Sometimes it’s enough to make a grown man cry. The deer season is just a few weeks away, and you’re as excited as a kid on Halloween. You’ve bought your license, your stands are up and your boss said you could have opening day off. There’s only one thing left to left to do, and that is to check your broadhead flight. You suspect everything is okay. After all, your practice arrows have been flying straight and true all summer long. Your first broadhead however goes awry. So does the second. Panic starts to take over. Your third shaft wobbles, as does your next several shafts. What’s going on?

If your field tips have been consistently wobble-free and your bow is well tuned, you may simply have a bad case of the jitters. Apprehension about THE first day can do funny things to people, especially bowhunters after they attach a razor sharp broadhead to their hunting shafts. Torquing the bow, lack of back tension, not picking a spot, target panic, plucking the string and poor follow through are just some of the problems brought about by anxiety.

Fortunately, the solution is simple. Relax! Take it easy! Concentrate on the basics, and your form will return in minutes. If your arrows are still flying off into the wild blue yonder, then you are experiencing more than an anxiety attack-you’ve got one or more of those dreaded tuning problems.

First check to see if ALL your shafts are going hay wire. One or two could be dinged or bent from your summer practice sessions. Even pulling an arrow from a target butt, if not done with care, can cause curvature to an aft. Look too at the nocks. You may have replaced one improperly by cutting or not cleaning the nock swage, or by not rotating the nock correctly for proper fletch clearance.

A simple spin test will show you if your other arrows are wobble-free. Sometimes machining tolerances between broadheads and bushings are too great which can lead to your broadheads wobbling all the way to the target. A plastic washer might eliminate the problem, but more often than not you’ll need to switch broadheads from one shaft to another in trial and error fashion until you find a combination that spins true.

Of course, if you have been practicing extensively with your broadheads, you might have damaged the blades or bent the ferrule. Examine each head closely, and if that’s the case replace the damaged head with a new one.

A gob of glue on one side of the insert can also cause your arrow to wobble near the broadhead. Simply reheat the glue around the insert, and then twist the insert with a pair of pliers to redistribute the glue. Be careful, those aluminum shafts can be hot.

Broadheads suddenly veering off course? A new bow quiver full of arrows can change your point of impact.

Broadheads suddenly veering off course? A new bow quiver full of arrows can change your point of impact.

Broadheads still veering off target? Think back. A common mistake archers make is adding something to the bow that wasn’t there during their summer practice sessions. Swatches of muff glued to your arrow rest or plunger button to silence an aluminum hunting shaft can have a deleterious effect on arrow flight. And a quiver full of arrows or a new stabilizer can sometimes change your broadhead’s point of impact leading you to erroneously believe your arrows have suddenly gone awry.

Did you make any changes to your equipment, like increasing the poundage of your bow, after you attached your broadheads? If so, did you turn the upper and lower limb bolts evenly? A change in bow poundage can adversely impact the spine of your arrow, and uneven stress on the limbs can stop the wheels or cams from rolling over simultaneously. This can interfere with the bow’s timing and cause your broadheads to porpoise up and down.

The most common explanation for poor broadhead flight however is lack of fletch clearance, often indicated by black on your arrow’s fletching. Indeed, the slightest interference between any part of the bow and the arrow’s fletching will ruin broadhead accuracy.

First check your bow for loose or damaged components. Start by tightening everything down with a set of Allen wrenches. A loose arrow rest, a cable guard that has turned into the bow or a bow sight that has slipped down into the arrow’s path can all cause your broadheads to fly haphazardly. Then give your bow a good look-see. Defective limbs are rare these days, but cracked launchers are not. A bent cable guard had me screaming for mercy one day until a friend noticed the unusual curvature. I must have stepped on the thing!
  
Next, eyeball your finished arrow to see if the fletching clears your cables, overdraw unit, center shot window and the forks on your arrow rest. You may need to rotate your nocks, adjust your cable guard, change your cable slide, remove part of your overdraw unit or try a different design arrow rest to get the clearance you need. And check out those arrow-rest support arms. They are notorious fletching grabbers!

If you can’t pinpoint the source of the interference, take the powder test. Spray your arrow rest, over draw unit sight window, cables, cable guard and the last eight inches of the fletched end of an arrow shaft with dry foot powder, and then shoot the shaft into a foam target. You don’t want the arrow to penetrate to the fletching. If the fletching comes in contact with any part of your bow, the foot powder will scuff or smear showing you the point(s) of contact and the position of the fletching as it leaves the bow. That should tell you if you need to rotate your nocks, readjust your cable guard, switch over to a lower profile fletching or change your style of arrow rest.

Arrows still wobbling? Your bow may not be as well tuned as you thought. According to Wayne Meritt, general manager of the Genesee Valley Taxidermy and Shooting Supplies complex in Caledonia, you may need to have your hunting set-up paper tuned at a qualified pro shop to achieve perfect arrow flight.

Tighten down all components. A loose arrow rest or cable guard can raise havoc with broadhead flight.

Tighten down all components. A loose arrow rest or cable guard can raise havoc with broadhead flight.

“A broadhead-tipped hunting shaft has the capacity to magnify any tuning error in the bow,” says Meritt, “causing the arrow to porpoise and/or fish-tail. Properly tuned however, your hunting shaft will look like a round dot all the way to the target.”

Generally, a tail-low tear indicates a low nocking point which can be easily corrected by raising you nocking point a 1/16″ at a time. A tail-high tear indicates a high nocking point. Lower the nocking point a 1/ 16″ at a time until you get the arrow point and fletching appear to enter the same hole. Once corrected, you arrows will stop porpoising. A tail-left tear usually indicates a weak arrow for right-handed shooters-lefties will expenience the opposite pattern. You can decrease your bow weight, use a lighter broadhead, switch to a stiffer shaft or increase the plunger button tension. Release shooters may have to move the arrow rest slightly to the left.

A tail-right tear usually indicates an arrow that is too stiff. Lefties again will see the opposite pattern. You can increase the bow weight, choose a weaker arrow, decrease the tension on the plunger button, or use a heavier broadhead. Release shooters may have to move the arrow rest slightly to the right.

There are however other variables including your shooting forn and the bow’s timing that can adversely affect the arrow’s flight through paper. That’s why visiting your local pro shop is most always in your best interest. Indeed, the paper test may verify what a good bow mechanic already suspects: an under spined arrow shaft is the second leading cause of poor broadhead flight.

“Many bowhunters, erroneously believe a lightly spined shaft will give them a speed advantage,” says Meritt. “After all, a flatter trajectory makes yardage estimation that much less of a problem. However, as a general rule of thumb, a lightly spined arrow does not mean more speed. In fact just the opposite may be true.

“When you set your hunting bow up with the correctly spined arrow, and you must include the shooter and shooting style in this equation, it will give you the flatest trajectory, the most speed, the most penetration, the most accuracy, and be the most forgiving in execution. Everything is gained by having a correctly spined arrow.

“For example, a 2114, 2213, and 2312 all weigh virtually the same, plus or a few grains. There is however a significant spine difference between these arrows. Why then would you want to shoot an arrow that borders on being under spined when you can shoot a properly spined shaft at the same weight?”

What about the fletching itself? Keep in mind that most finger shooters do best with standard five inch fletchings set with a slight helical. A release shooter may get away a shorter fletch or a fletch with less profile if the bow is well tuned.

One final note. Should you line up the broadhead blades with your arrow’s fletching? I hear different opinions from knowledgeable mechanics across the country. It doesn’t seem to be a requirement, but on the other hand many believe this set-up does seem to be more forgiving. One thing everybody seems to agree on, and that is it can’t hurt. Good hunting!

Paper Tuning
Generally, a tail-low tear indicates a low nocking point which can be easily corrected by raising you nocking point a 1/16″ at a time.

A tail-high tear indicates a high nocking point. Lower the nocking point a 1/ 16″ at a time until you get the arrow point and fletching appear to enter the same hole. Once corrected, you arrows will stop porpoising.

A tail-left tear usually indicates a weak arrow for right-handed shooters-lefties will expenience the opposite pattern. You can decrease your bow weight, use a lighter broadhead, switch to a stiffer shaft or increase the plunger button tension. Release shooters may have to move the arrow rest slightly to the left.

A tail-right tear usually indicates an arrow that is too stiff. Lefties again will see the opposite pattern. You can increase the bow weight, choose a weaker arrow, decrease the tension on the plunger button, or use a heavier broadhead. Release shooters may have to move the arrow rest slightly to the right.

 

Do you feel capable of tuning your own bow?

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