Bow Tuning Part 2 by Andrew Smith (Perris
Archery)
 Copyright Bow International Magazine
(2006) No reproduction is permitted of any of the
material published below without prior consent of Bow International in
writing.
First published in Bow Magazine issue 38:
July/Aug 06.
Click on the illustrations
below to enlarge
Original PDF of the
article can be downloaded here
Bow Tuning Part
Two
In
Part One (issue 36) I explained the checks and actions required to set up
your bow so that it was ready to shoot. The adjustments were not perfect
but as this information is targeted at beginners the guidelines were more
than accurate enough to allow you to get out on to the range and start
practicing your shooting form.
In
Part Two we will now look a little deeper into how you can get your arrows
to fly straighter to the target as you may already have noticed that when
shooting at longer distances say 60 yards or 50m that your arrows tend to
wobble a bit in flight.
All the
adjustments and results we will be looking at will require you to shoot
your arrows, so your current ability will have a big influence on how much
difference these checks and changes will make to your arrow flight and
scores. To see any benefit at all you will have to be honest with yourself
about your skill level and if currently you are not getting all your
arrows on the target at 40 yards (30m) with reasonable groups of around
18” (45cm) in diameter, then this is not for you at this time and you
will benefit far more by continuing to improve your shooting form with
help from your club coaches. Ideally on a calm day or indoors you should be capable of
getting consistent groups around 10 or 25cm in diameter at 20 yards.
Part One recap
A
quick recap on the adjustments made in Part One: We set the nocking point,
bracing height, tiller, fitted an arrow rest, adjusted the centre shot and
looked at adjusting the button (if fitted) and finally I stressed the
importance of having the correct arrows (spine & length) to match you
and your bow.
It
is important for this next stage and assumed that you have set your bow up
as suggested in Part One, this is also a good reference point should you
have to start over again for any reason. The additional pieces of kit that
you will now need are a button (if you are not currently using one) some
thin insulation tape and an arrow rest that can be used with a button.
Aluminium arrows
only
As
in Part One all the adjustments we will cover will only apply to aluminium
arrows as these are the most common on the beginners shooting line,
offering the best in durability, the ease to get replacements and finally
cost. As you progress you will notice a lot of archers shooting carbon
arrows or A/C arrows. These are very high tech and offer greater accuracy
at the longer distances because they fly faster and are less affected by
the wind if tuned correctly. It is also worth noting that many good
National and International records have been set in the past with
aluminium arrows. Carbon arrows also behave differently in flight so some
of the methods especially the walk back test mentioned here is not
suitable with these types of arrows. All this is a long way off but once
you are ready for carbon arrows you will have a better understanding of
how your bow and arrows behave and probably have read a few advanced
articles on bow tuning. It is also a topic that takes up much time on the
shooting line and archery related forums. Just remember with all types of
bow tuning it is always best to keep it as simple as possible because
until you are shooting scores in excess of GNAS Bowman/FITA 1100 it is
improvements in your shooting form which will have the most influence on
your progress.
The Button
In
Part One I explained that it was not necessary to fit a button to your bow
because a Hoyt or similar rest with a plastic strip to act, as a crude
button would be sufficient. Now that you have been shooting for a few
months and started to group your arrows a button if set up correctly will
now help you to make your bow more accurate and be more forgiving of bad
shots. All of the adjustments mentioned here with the exception of the
nocking point will be made using the button.
Selecting a button
You do
not need to go out and buy the most expensive button on the market. A
cheap one for around £7 will be ok but make sure the plunger movement
feels smooth and is not sticking (sometimes you can take the plunger out
and smooth down the plastic burrs causing the problem). Buttons around the
£18 mark provide the best compromise between price and quality and
longevity. I have one button in this price range that is now 16 years old
and still going strong. The top of the range buttons do however provide
better micro adjustment and ease of use when tuning your arrows.
Bracing Height
In
Part One I suggested setting the bracing height at the top end of the
manufacturers suggested range. This range is usually about 1inch or 2.5cm,
unfortunately nobody can tell you the exact measurement, as this is unique
to you. When you shoot you will notice that the bow makes a noise,
depending on the bracing height this noise will get quieter or louder.
Most bows shoot best at the quietest point, this can be found by shooting
the bow at different bracing heights (within the manufacture’s guide
lines), adjusting the length by adding or removing twists in the string
but making sure the string is long enough to still have some twists when
finished. Once you have completed this exercise you will find that there
are 2 ideal bracing heights one at the bottom of the range and one at the
top; I suggest that you select the higher bracing height as this will help
with better arrow clearance and make the shot a little more forgiving.
Is your sight level?
Before
we start you may have noticed that when you shoot longer distances you
have had to adjust the windage on your sight even on calm days. The most
common reason for this is that the sight bar is not running parallel to
the bowstring; when you move the sight pin you are also changing the
windage adjustment. Most sights have adjusting screws so that you can
correct this.
The
Bare shaft & Walk back tests
How do we know that
these adjustments actually work?
All the
adjustments suggested here are not cutting edge and have been refined over
many years by top archers around the world, they have through time, proved
to be the most reliable way of setting up your equipment to match your
shooting style and ability. The logic being that fletchings help to steer
and stabilise the arrow in flight so if you can get the bare shaft to fly
relatively straight then there will be less work for the fletchings to do,
which in turn means less drag and more arrow speed hence a more accurate
arrow flight.
There
is a set order in which these adjustments should be undertaken but it is
not set in stone but if you do follow the suggested order it will be
easier to make sense of the results and make the necessary adjustments
correctly.
What will these
tests prove?
The
test results will show you what your arrows are doing in flight and what
adjustments will be required to make the arrow flight more accurate.
Your
shooting posture, skill level and release as well as your arrows and bow
set up all have a bearing on how straight your arrows fly so don’t
expect your results to match exactly those in the pictures, but as you
improve so will your results.
Put your bow
together correctly & warm up
The
first step is to put your bow together making sure that it is strung
correctly, hopefully you will be in the habit of checking that the limbs
are the right way round and not twisted each time you string the bow. As
all the accessories you use to shoot your bow will have an effect on the
adjustments we are about to make it is important to attach these to the
bow, for example the longrod, which you may or may not have added at this
stage. If you are now shooting with a clicker then you will also be
shooting these tests using it and lastly do not forget to shoot with the
same tab as you normally do.
It
is important to warm up before shooting and best to shoot a few ends
before starting to get you in to your shooting stride.
Note
to all left handed archers: Despite also being a left-handed archer it has
been pointed out to me that the majority of archers are right-handed so
the results shown will be relevant to a right-handed archers. Left-handed
results are reversed except the nocking point, which is true for both.
1)
The bare shaft test. (Part 1 setting the nocking point position on the
string)
This
test is shot at 10 yards (9m) and you will need to remove the fletchings
from one of you arrows.
Sight
position: Set the sight up for a distance of 10 yards (9m) and set the
windage so that the sight pin is above the arrow.
In
this test we are only interested where the bare shaft arrow lands in
relation to the fletched arrow group vertically if it is to the left or
right it does not matter.
For
this test you will need to remove the brass nocking points and create a
temporary nocking point using insulation tape. This will make it easier to
move to find the best position. Start by setting this at the same point as
the brass nocking points.
Set your
target up at 10 yards (9m), it can be blank with an aiming point like a
target pin or a normal target face.
Shoot
3 or 6 arrows with fletchings and the bare shaft at the same point on the
target. We are only interested in whether the bare shaft has landed above
or below the group. If the bare shaft is above the group then your nocking
point is too high and below the group too low on the string.
You
are trying to achieve a nocking point position where the bare shaft is
about 1-3 inches below the group on the horizontal plain.
I
would suggest that you repeat the process a couple of times with each
nocking point setting and if the bare shaft is in roughly the same place
move the nocking point about 1/8th of an inch each time in the
right direction (up if bare shaft is below the group and down if it is
above). You should keep repeating the test and making adjustments until
you get the desired result. Finally when finished don’t forget to
re-apply your brass nocking points.
Horizontal
adjustments setting the button spring pressure for a right- handed archer
(opposite if you are left- handed).
This
test is also done at 10 yards (9m) and this time we are interested on how
close the bare shaft hits the target in relation to the fletched group on
the horizontal plain.
Ideally
in this test we are looking for the bare shaft to land in the group of
fletched arrows or just to the left at 7 o’clock.
If
the bare shaft lands to the right of the group then the spring pressure is
set too soft and likewise to the left the spring is too hard. To adjust
the button loosen the top locking grub screw on the side of the button and
using the allen key in the end of the button turn it clockwise to stiffen
the spring and anti-clockwise to weaken the spring tension. Initially how
much you move it will depend on where the bare shaft lands in relation to
the fletched group, but for example, if the bare shaft lands at just below
9 o’clock in the white with the fletched arrows grouped in the gold then
one whole turn anti-clockwise is worth doing after that quarter turns are
all it should take.
Fig
1 Nocking point too low, Fig 2 Nocking point too high, Fig 3 Finished
result
2) Walk back test
Once
you have completed the bare shaft testing you can leave it at that
remembering to re-fletch your bare shaft. However there is an additional
check that you can do called the walk back test. The results of this test
measure your arrow flight over a greater distance, identifying additional
adjustments to your centre shot, button spring pressure and possibly also
highlighting other issues such as poor arrow clearance.
The
test is quite simple but to get the best results you need to have a nice
calm day or a long indoor hall.
Set
up a target at 50 yards and put a second boss below it on the ground and
put a target pin at 12’oclock just in the black on the top target (this
will be your aiming point) now go and stand 5 yards in front of the target
and set your sight for 5 yards (don’t adjust your windage as it should
still be set so the pin is above the arrow).
Shoot
one arrow at the target aiming at the target pin, then walk back 5 yards
and shoot another arrow again aiming at the target pin. Repeat this until
your last arrow is at the bottom of the second boss.
The
results of where your arrows land will give you an indication of how your
arrows will fly at longer distances and whether your centre shot or button
spring tension are correct. Keep repeating the tests and adjustments until
you get a pattern that is more or less a straight line taking in to
consideration your shooting ability.
If
as you go back your arrows drift to the right or left then you will need
to adjust your centre shot, drifting to the left indicates that your
centre shot is too far out and vice versa. The adjustments need to be
quite small only about a quarter of a turn each time.
If
you get a pattern as with the arrows creating a curve to the left then
your spring tension is too stiff. Try reducing the spring tension by
1-quarter if it’s the opposite then your spring pressure is too soft
(again the reverse for left-handed archers).
The
pictures here are exaggerated but it is important to adjust the centre
shot first, the objective is to get the arrows forming a relatively
straight line.
Once
you have completed this exercise and you are happy with the results go
back to 10 yards (9m) and repeat the bare shaft test. You will most
probably find that the bare shaft no longer lands where it did before
doing the walk back test. This is because you have now found a more
suitable set up for you. Make a note of the position of the bare shaft and
the group. This way if you change something or something breaks you can
quickly do a bare shaft test and set the nocking point and button to get
the bare shaft to hit in the same place again, saving you all that time
doing the walk back tests.
Fig
1 Centre shot too far out, Fig 2 Spring tension too stiff Fig 3 Finished
result
My patterns do not
match any of the pictures
This
is quite common and you have to take in to consideration your shooting
ability, but if after re-checking all the adjustments the results still do
not seem right then there might be a number of reasons for this:-
a)
Not able to get the bare shaft to move closer to the fletched group when
adjusting the spring tension. The most popular reason for this is that the
arrows are the wrong spine, they are either too weak or too stiff. The
solution after re-checking with your club coach is to buy the correct
arrows.
b) Arrow
clearance: Where a part at the back of the arrow is hitting the bow on
release. There are a number of ways to check this but my favourite is to
sprinkle a fine dust of talcum powder around the arrow rest and riser and
shoot an arrow. You will see marks in the talcum powder if the arrow is
hitting the riser or arrow rest. In most cases it is the fletchings that
hit the bow so you might also see damage to those. This is a sign of one
or more of the following: a
bad loose, low bracing height, incorrect centre shot or button spring
pressure adjustment, too high or too low nocking point, fletchings that
are too big and finally too stiff or too weak arrows.
c)
Odd left and right shots, Make sure that when you shoot you line the
string picture up the same each time otherwise this will also create
erratic left and right shots.
If
after checking these possible options you are still getting mixed results
don’t worry about it, set your bow back to as it was in Part One and
just keep practicing and seek advice from your club coach or local Pro
Shop.
Once
you have your bow set up I suggest that you now forget about bow tuning
for the foreseeable future and concentrate on your shooting form in the
knowledge that this will get you to 1st class and beyond. It
will be necessary to check the tune if something breaks, you get new
arrows and as your shooting ability improves but no more than once
possibly twice a year.
Finally,
I would like to thank Tony Preston of Perris Archery for providing all of
the equipment used in both articles and Bert Hastings again of Perris
Archery for agreeing to feature in the pictures used in Part One.
Copyright Bow
International Magazine (2006) No reproduction is
permitted of any of the material published above without prior consent of
Bow International in writing.
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FINALLY,
THE GOOD NEWS IF ALL THE ABOVE INFORMATION SEEMS A BIT DAUNTING WE DO RUN
INTERMEDIATE COURSES AND BOW TUNING SESSIONS ON A ONE 2 ONE AND GROUP
BASIS PLEASE CONTACT US FOR MORE DETAILS.
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