HuntingNet.com Forums - Compilation of Tuning Articles

A friend put these together for me and I found them to be good reading. Hopefully you guys will too. :)

Fritz

BROADHEAD TUNING
by Bruce Barrie

Through the years many articles have been written on the subject of broadhead
tuning. There are some basic guidelines to follow that have worked well for me
and other bowhunters that should make tuning your broadheads easier.
Unlike field points, broadhead tipped arrows want to fight with your fletching
to steer the arrow from the front end. If your bow is not properly tuned, the
arrow will leave the bow with a fish tailing effect. If your arrow does not have
adequate fletching to correct this, the broadhead will take over and begin to
windplane. Not only is this important for accuracy, but also for maximum
penetration. Good arrow flight is the single most important factor which effects
penetration.
Before we get into paper tuning your arrows, a few minor changes can be made
with your set-up to help make your broadheads fly truer. To begin with, larger
diameter broadheads are more critical for flight than smaller diameter
broadheads. Also, vanes can be more critical to tune with broadheads compared to
feathers. In addition, the faster the bow the more difficult it becomes to
obtain good arrow flight. I have found that 260 feet per second appears to be
the threshold. Set-ups over 260 feet per second are much more touchy. I also
have found that a front of center balance between 10 and 12 percent gives me the
best arrow flight. Target shooters may be able to get by with less than 10% FOC
balance but for us average shooters, anything less than 10% can be touchy.
I like to begin paper tuning my arrows with field points. The arrow shaft
company, Easton, makes an excellent chart to help with our paper tuning effort.
I have found that if I get my field points to tune well through paper, I almost
always get my broadheads to fly well. If you want to take it to the next level,
you can repeat your paper tuning process with your broadheads.
Randy Ulmer, one of Rocky Mountains famous staff shooters believes that , "By
tuning the bow to shoot a bullet hole through paper, you are minimizing the job
the fletching must do allowing the arrow to get off to a good start. The first
20 feet the arrow travels is critical in determining final arrow performance."
Jackie Caudle, another staff shooter for Barrie Archery believes that a slight
high left tear for a right hand shooter is optimal.
As you can see, even the top shooters have their own special system to setting
up what they feel is the best for them. The point is, you want to eliminate any
erratic tears when you tune through paper. By doing so, you will have a much
better chance of getting your set-up tuned for broadheads.
If you have any question, comments, concerns, or suggestions for future "Cutting
Edge" columns, E-mail me at [email protected].

ADJUSTING BOW SITES:

Adjusting bow sites is one of the most often confused procedures I have ever
seen. There is one rule to remember: Move the site to the arrow.

1. If you are shooting high move your pin up.
2. If you are shooting low move your pin down.
3. If you are shooting left move the pin to the left.
4. If you are shooting right move the pin to the right.

Peep Sight: Moving a peep up make the point of impact move up, moving it down
moves the point of impact down.

Be patient and move the site in small increments.
Remember when buying a bow site to look for ease of adjustment. It is very handy
to be able to move all of the pins vertically and horizontally at one time. This
feature will cost a little more but will be worth it in the long run.
Buy a site that will stay tight!! Cheap sites often come loose and on the range
it can mean lost points but in the field it can be the difference between a kill
and a miss. Loose sites make NOISE! check them before every hunt.

Straight shaft..

Properly aligned insert and nock..

Well made head, properly aligned on shaft..

Well tuned bow shot with solid form..

=Straight flying arrows

PAPER TUNING

Paper Tuning is a method of bow tuning popular with compound archers. The method
is to shoot arrows through a sheet of paper placed in front of the bow and
adjusting the bow until the tear pattern is a 'bullet hole' i.e. the fletchings
pass through the same hole as the arrow pile. The arrow is therefore leaving the
bow straight with no vertical or horizontal rotation.

For recurve archers, using the paper tuning approach has limitations because of
the Archers Paradox effect. The effect of the finger release results in the
arrow leaving the bow with significant vibration in the horizontal plane. The
following diagram indicate the problem:-

Because the arrow is flexing, even with a perfectly tuned setup you will
probably get a horizontal tear in the paper because of vibration of the arrow as
it passes through the paper. (illustrated by the green line).

If the arrow is of length 'L' and speed 'V' then the time for arrow to pass
through the paper is L/V.

If the arrow is vibrating at frequency 'F' then the time to go through a
complete bending cycle is 1/F.

E.g if L = 80 cm, V = 55 metres/sec and F = 60 cycles/second then the time for
the arrow to go through the paper is 80/5500 = 0.015 seconds and the time per
vibrational cycle is 1/60 = .017 seconds. The number of bending cycles that the
arrow goes through when passing through the paper is 0.015/0.017 = 0.9 cycles.
In general we can expect the arrow to go through multiple bends while passing
through the paper which will result in a horizontal tear varying from zero (the
arrow snakes through a single hole - unlikely but possible) to the amount the
arrow flexes sideways (which depends on the arrow - anything up to 2 inches
say).

You can use paper tuning in principle for three purposes, arrow dynamic spine
assessment, nocking point adjustment and pressure button adjustment.

Spine Assessment

If the arrow comes out of the bow with a large amount of rotation (very
weak/stiff arrow) then you will get a very wide horizontal tear in the paper,
the combination of the arrow vibration and its rotation. If this tear is too big
its unlikely that any amount of bow tinkering or tuning will produce a good
flying arrow and the arrow needs to be changed or replaced. Rick Stonebraker's
tuning guide puts the maximum allowable horizontal tear at 3 inches. Any larger
then this then a weaker/stiffer arrow as appropriate is required.

Nocking Point Adjustment

There is a negligible amount of Archers Paradox effect in the vertical plane so
any vertical tears in the paper result from arrow rotation. You can therefore
adust the bow (usually the nocking point) towards having zero vertical tear
implying the arrow is leaving the bow with no rotation in the vertical plane. As
any vertical rotation will result in the arrow porpoising it is important that
the 'zero tear' is obtained over a range of distances. At very short distances
the amount the the arrow will have rotated will be small - low tuning
sensitivity. At longer distances the arrow may have rolled over to the
horizontal or even be aligned in the other direction - possibility of false
interpretation. The tuning 'distance range' will depend on the arrow (say 2-10
metres)

Pressure Button Adjustment

In the horizontal plane the paper tear is essentially going to be a random
combination of the arrow vibration and any arrow rotation in the horizontal
plane. Even a perfectly tuned bow is going to give an unpredictable horizontal
tear depending on how the arrow 'snakes' through the paper. For pressure button
adjustment therefore paper tuning is not a method that can be recommended

If an archer tries to get a bullet hole tear by adusting the pressure button
what effectively is happening is that the arrow rotation (mis-tune) is being
used to offset the arrow vibration effect as far as the paper tear is concerned.
As the arrow rotation tear effect depends on the bow to paper distance if at a
specific distance you get a bullet hole tear then by moving forward or backwards
the tear magically reappears again.

Approaches to tuning inevitably comes down to archers preference (some swear by,
some swear at). In my own ranked list of ways of bow tuning paper tuning resides
at the bottom.

Tuning Your Bow
by Roger Wheaton
For the last couple of issues we have discussed pre-shot preparation as a mean
to enhance your shooting skills. All the preparations in the world, however,
will not help if your equipment is not properly tuned. Tuning requires some
equipment, knowledge, and, often, more than a little time. But more than that,
it demands some intuition and ingenuity to understand the variety of factors
which impact upon arrow flight. What is tuning and why is it so important?

Bow tuning is simply aligning the bow and arrow partnership so that you can
achieve maximum efficiency with each individual shot. Maximum efficiency is
achieved when, upon release, the arrow will fly with minimum oscillation,
displacement, and vibration and consistently hit the spot at which it was aimed
at the instant of release. Although some arrows may consistently hit the
target, arrow flight may be poor. Properly tuned equipment will yield clean
arrow flight as well as consistency in grouping. The later will provide better
arrow speed, better trajectory, better penetration, and suffer reduced impact
from environmental effects.

Broadheads demand super clean arrow flight or grouping will suffer significantly
as the arrow fights the Broadheads tendency to windplane. But how can we
achieve better arrow flight? There are several ways to tune your bow and arrow
system; however, they all begin with a properly timed bow. Timing refers to the
relationship of one eccentric to the other. Single cam bows obviously don't
have the timing problem. Bows will come from the factory roughly timed and
often require additional work. Poor timing will usually display itself by feel.
As you draw the bow near full draw, the stop should be felt as a single solid
point. If you feel two distinct, small bumps as your bow reaches full draw,
your eccentrics are out of synch and must be adjusted. Adjustment can be
effected by twisting the cable from either the top or bottom eccentric by two
turns and then testing the feel again. If the bumps disappear or feel closer
together, you have adjusted the cable properly. Obviously, if the bumps are
further apart, you should either untwist the same cable four turns, or twist the
other cable four turns. Continue using small increments of twists until the
separate bumps disappear. Eccentric timing in small increments, even though
they feel balanced, can be used to fine-tune the bow. More on this topic later.

Finding the right arrow to complement your perfectly timed bow is a fairly
simple matter. The Easton Shaft Size Selection Chart is a good starting point.
This chart is in most catalogues and is available at your archery pro shop.
Most dealers also have the software for their computers that can provide
detailed information on shaft selection as well. In general, if you are a good
release shooter looking for target arrows, you can usually safely select arrow
one to two sizes weaker in spine than the Easton Chart specifies. However, if
you are a casual or average shooter or simply choosing hunting shafts, I prefer
to go with the recommended size shaft. Stiff shafts handle broadheads much
better than weaker shafts. Finger shooters, in general, should not go to
smaller than recommended shafts. The best option is to follow the advice of
your pro shop, especially if they have knowledge of your shooting skill level.
Shaft selection is based upon some key elements: bow weight; arrow length; point
weight; release style, and, type of eccentric. Each of these factors impact
significantly on the stress applied to the shaft upon release, specifically the
amount of bend which occurs in the shaft as the bowstring accelerates the tail
of the shaft against the resistance of the point. In turn, these factors
determine how well the arrow and fletching clear the arrow rest and how soon the
arrow shaft dissipates the bending and vibration caused by the rapid
acceleration.

The following tuning instructions are intended to help you minimize the negative
impacts of the shot on your arrow flight. To be effective, these steps must be
done in sequence. The procedure described is for a right-handed archer and
should be reversed for left-handed shooters. I usually begin by setting my bow
with a perfect center-shot. This means adjusting my arrow rest so that I can,
by aligning the bowstring against the center of the riser as I hold the bow out
in front of me, I can then see the bowstring also aligned down the center of a
nocked arrowshaft. This can also usually be achieved by looking along a nocked
arrow from above and adjusting the arrowrest so that the arrow is parallel to
the arrowshelf on a machined riser. A commercial centershot tool which can be
used to quickly and more accurately achieve a centershot setup is also
available. Once I establish centershot, I then set my nock 3/16" above center
(use 5/16" for finger shooters). With this setup, I then paper tune to achieve
my best arrow flight. Any rigid frame that will hold a newspaper sheet at level
shooting height will work. Place the paper tester about five feet in front of a
target. Stand 5 feet in front of the paper and shoot your best shot through the
paper. This will give you an idea of arrow orientation as it leaves the bow.
The tear should show a small, round indentation representing the point and sharp
tears where the vanes passed through as well. If the vane marks are centered
around the point (a bullet hole pattern), the arrow left the bow neatly without
apparent disturbance. Normally, you will notice the point mark displaced
slightly from the vane marks. I prefer to see this displacement with the vanes
slightly left and above the point mark. Usually, my arrows will ultimately group
better with this pattern than they will if I have a nice, neat bullet hole
pattern. What can cause displacement of the vanes from the point? If the
displacement is large, it is best at this time to check vane clearance through
your arrow rest. This can be done by spraying your arrow at the rear and over
the vanes with a powder such as Desenex foot spray. Shoot the arrow into a bale
and then examine the powder for marks. If the vanes show marks indicating that
they hit the arrow rest, rotate the nock or adjust the rest until these marks
are no longer visible. Clearance, particularly with small diameter carbon
arrows, can cause significant problems, but must be resolved before continuing.
Minor adjustments in nock position, centershot position, or even eccentric
timing can sometimes solve this riddle. Make small adjustments to the current
settings then retest until clearance is achieved. Occasionally, a new rest or
fletching pattern must be used. Once clearance is established, continue with
the paper test. Minor adjustments to the centershot and nocking point usually
can achieve a good paper hole. Vane tears left or right usually require a
movement of the arrowrest to the left or right, respectively, but often it will
work in reverse. Vane tears high or low usually require a movement of the
nocking point down or up, respectively. Resolve vane high or low tears before
working on left and right tears. An ideal pattern would be a vane tear 1/4"
high and l/4" left. Perfect tears often indicate perfect arrow flight, but may
also indicate a very critical relationship between the fletching, nock, and
arrowrest. When satisfied with your paper tear at five feet, back up to about
fifteen feet and continue to adjust your tear. Finally, do it all over again at
ten to fifteen yards. If you have a sharp vertical tear that doesn't change as
you make adjustments to the arrowrest, the problem is probably in eccentric
timing. Try adjusting eccentric timing by twisting either cable extension one
turn at a time and see if that eliminates the tear in the paper, eventually
allowing adjustments to the rest to effect the paper tear. Once I am satisfied
with my arrow flight, I fine-tune the system by shooting groups at a vertical
and horizontal line. Make a cross on a piece of cardboard using black
electrician's tape strips about two feet long. Start at twenty yards and work
out as far as you like in ten-yard increments. Aim first at the horizontal
stripe and shoot four arrows. If these arrows show vertical displacement, make
a minor adjustment to the nocking point and reshoot. Continue to do this until
the vertical displacement disappears. Using the same procedure, shoot at the
vertical line adjusting the centershot in minor increments until the horizontal
displacement disappears. Then back out to a greater distance and check
displacement. Again make minor adjustments until maximum accuracy is achieved.
Finally, I try to maximize my aiming capability by tiller tuning. Tiller tuning
is simply a way to find the point at which you are able to hold best on the
spot. By making minor adjustments to the tiller, one can usually find a point at
which the bow will hold well on the spot. Record your nocking point position and
reposition your nock each time you make an adjustment to the tiller. Select a
yardage at which you can shoot very accurately. Fifty or sixty yards are
excellent. Shoot a group of four to six arrows and evaluate your group. Then
beginning with either the top or bottom weight bolt, increase the poundage by
1/4 turn. Reposition your nock if necessary and shoot another group. Note how
the bow held on the spot with regard to the previous position and also evaluate
your group. Continue in l/4 turn increments for one full turn evaluating the
results of the grouping and how the bow held on the target. Return the bolt to
the original position and then go through the same procedure with the other
weight bolt. You will probably find one or two points where you were able to
hold better on the target and thus should group better as well. To find more
about tuning, there are several publications available to assist you. Larry Wise
has written a series of books on tuning and shooting to include one specifically
on broadheads. Robin Hood Videos also have published a series of videotapes on
shooting that includes tuning instructions. Kirk Ethridge's book, Professional
Archery Technique, includes a chapter on tuning. Also available at low cost is a
series of Technical Manuals published by Easton. Some of these publications
include detailed information on tuning techniques. Your local pro shop is the
best place to find professional assistance in tuning. A second source for help
is the local hotshot, if he/she is willing to help. Remember, the above is only
one means of tuning. There are other ways equally as successful. The key is to
take a step by step process and follow it in detail. There is no quick and
simple way to tune a bow to its maximum efficiency, but you can achieve success
with patience and persistence.