Bow Tuning Part
1 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 37:
May/June 06.
Click on the illustrations
below to enlarge
I
think it is fair to say that most archers cannot resist the urge to fiddle
and change things on their bow in pursuit of higher scores.
In
most cases this urge starts just after you have bought your first bow and
along the shooting line you start to hear the immortal words not covered
on your beginners course “I need to retune my bow”, “My arrows are
now flying better since I tuned it” or after a particularly bad days
shooting “I have not had the time to tune my bow ”
In
the first part of this two-part article I will explain the checks and
adjustments you will need to make on your bow before you go out and shoot.
In part two I will explain how after you have been shooting for a while
you can make further adjustments, which will help with your shooting
accuracy.
This
article has been especially written for archers who have only been
shooting for a short while and have taken the plunge to invest in their
own equipment and as most archers first bow is a takedown recurve bow with
aluminium arrows I have concentrated on setting up this type of
configuration.
How much bow
tuning do you need to do before you can stand on the line and shoot at the
target?
Well
it depends, if you have bought your bow from a Pro Shop and relied on
their skill and expertise to set it up correctly, or you acquired your bow
from elsewhere with the guidance of your club coach and they have checked
your equipment and set it up for you then its job done. I would suggest
that you leave well alone and concentrate on your shooting form, because
at this stage you will achieve much better results and enjoyment from the
sport by shooting rather than anytime spent on bow tuning. However, by
reading the rest of this article you will have a better understanding of
the adjustments that have been made to your bow and as these adjustments
are the building blocks for part two it will also help you in your
understanding of how a bow actually works.
The
objective of tuning your bow is to set it up so that the arrow leaves the
bow and flies as cleanly as possible to the target, the more an arrow
wobbles in flight the less accurate it will be. Unfortunately it is not a
simple matter of changing a few settings on the bow, how you shoot also
has a big part to play in this process. This is why I repeat that if your
bow is set up as suggested in this article then there is little to be
gained from spending time bow tuning. But don’t worry if you think you
are missing out, as soon as you start shooting nice groups at 30 to 40
yards (25-30M) obviously less for juniors, a little additional bow tuning
coupled with your improvement in shooting form will help your arrows to
fly more accurately to the target.
1) Putting the
bow together
The
first stage in setting your bow up is to make sure that it is put together
properly, this means slotting the top and bottom limbs in the correct limb
pockets, screwing in the button of you have one and stringing the bow
using a bow stringer, making sure the string is not upside down (the
largest loop on the string is attached to the top limb). It is very
important to string your bow correctly as a lot of damage can be done to
the limbs if you try some of the other methods you see on club nights.
2) Limb
alignment
With
the odd exception most modern metal handle bows available today are made
with international fit limb pockets, the advantage being that you can mix
and match limbs and handles from different manufactures. The downside is
that certain set up adjustments that used to be the preserve of the bowyer
have now been past on to you. This is because each manufacturers product
will be slightly different, so now handles come with additional
adjustments to account for these small differences.
The
two adjustments that can be made on most bows are the tiller and
increasing or decreasing the poundage of the limbs (by about 10%), however
new beginner/intermediate handles like the Hoyt Eclipse now include the
same limb adjustment as seen on their more expensive handles where you can
also adjust the limb alignment.
To
make sure that the limb tips are moving in the same direction when you let
go of the string, the first check and adjustment if necessary is to see if
the string runs directly through the middle of each limb and that the limb
tips are not twisted. To check this look down the length of the string as
in picture 2 & 2a, checking both the top and the bottom limbs.
To correct any errors depends on your handle adjustment options, for the
Hoyt Eclipse it’s a matter of adjusting a screw in the limb pockets for
others it’s a matter of gripping the limb tip and twisting it gently in
the opposite direction to the twist. However the best option is to ask for
help from your coach or local Pro Shop because getting this wrong could
necessitate a new set of limbs.
Note:
To find the limb centres just stick a piece of masking tape across the
back of both limbs just below where the limb meets the handle and measure
and mark the exact mid point. I also suggest that you check the string
alignment every time you string your bow, you should not have to make any
major changes but make sure that the limb tips are not twisted and the
string is in the groove of the limb before shooting. If you shoot a bow
with twisted limbs it will not be as accurate as it should be and
eventually the twist will become permanent.
3)
Bow tiller
When
you look at your bow you will notice that the arrow rest is not positioned
in the dead centre of the bow and the hand that holds the bow is below the
horizontal line from the point where you draw the string. This means there
is an imbalance in the forces on the bow at full drawer causing the top
limb to want to tilt towards you. The ideal solution would be for your arm
and arrow to be in exactly the same place, but obviously this is not
physically possible so we have to readdress this imbalance by moving the
bottom limb closer to the string than the top, this is called adjusting
the tiller. The difference is quite small only 1/8th (3-5mm) of
an inch but enough to improve the balance of the bow. This adjustment is
done by adjusting the poundage screw on the bottom limb and checked and
measured using a bow square. If your bow cannot be adjusted for tiller do
not worry we will assume that it is correct and in part two we will
explore how you can fine tune this just by changing the nocking point.
4) Bracing
height
The
bracing height is the distance the centre of the string is away from the
handle when the bow is strung. All bows have a recommended bracing height
range listed in the manual, most measurements are from the centre of the
button or from the throat of the handle to the string. It is important at
this stage that your bracing height is within the recommended range and
again we will cover finding the optimum adjustment in part two. For now by
shortening or lengthening the string (by adding or removing twists in the
string) set the bracing height so that it is approximately a ¼”(6mm)
below the top of the range. This will help with arrow clearance to be
discussed later on and ensures that the limbs will work properly.
5) Nocking Point
The
nocking point is the point on the string where you attach the arrow for
now we will be using the brass nocking points clipped on to the string
using a nock set tool. Basically you need to set these at 1/8th
(3-5mm) of an inch above square
6)
A note about arrows
You
will probably have heard the expression “your arrows have to be matched
to your bow” so to ensure that we all understand what this means, here
is a brief recap.
When
you shoot arrows using a finger release you are familiar with the string
going forwards but during the release you also push the string sideways
towards you, how much deviation there is depends on how good your release
is. The forward and sideways motion creates forces within the arrow to
make it bend (on the horizontal plane) one way when the arrow leaves the
string and in the opposite direction as it clears the bow handle, the
arrow will keep repeating this motion for a while before settling down and
hitting the target. This motion is commonly known as the archers’
paradox and the more powerful the bow the more of the force is channelled
through the arrow, which in turn will make the arrow bend more.
If
the arrow bends too easily two things will happen in flight 1) it will
take too long to settle down before it hits the target and 2) the arrow
will have a tendency to bear to the right (right handed archer and the
opposite for a left handed archer) and likewise if the arrow is too stiff
it will fly off to the left and not bend enough so that the back of the
arrow might hit the arrow rest. In both cases the accuracy of the arrow
will be affected.
Arrow
Manufactures take in to account the archers paradox and make a range of
arrow shafts for different bow poundage’s. So when you buy your arrows
the Pro Shop will take into consideration your draw length and your limb
holding weight (or peak weight) at full draw and select arrows that will
fly out of your bow correctly.
As
pictures tend to speak louder than words, a few years ago Beiter using
slow motion cameras filmed some top archers shooting, whilst the full
version is available in DVD format if you go to their website you can see
sample clips which will clearly show what is meant by the archers paradox.
http://www.wernerbeiter.com/en/products/videos/video.php
7)
Setting the (just over) Centre Shot with and without a button
In
section 6 about arrows I mentioned the archers paradox, the final setting
required before you are ready to shoot is to give a bit of help to the
arrow to make sure that it clears the bow the proviso being that you have
acquired arrows that are matched to your bow.
What
you need to achieve with this set up is the whole of the arrow tip (pile)
pointing to the outside (left right handed archer and right left handed
archer) of the string as in picture 6. Making sure that the string is
lined up with the centre of each limb.
Set up without a
pressure button
In
the first few months of shooting it is not necessary to use a pressure
button providing the arrow rest you choose has a plastic protrusion to act
like a button, by far the most popular is the Hoyt Super Pro rest and
these are also quite cheap at around £2 each so not too expensive to
replace should the need arise. I personally would recommend this set up
for the first few months even if you do have a button as it keeps things
simple.
Note:
The majority of new bows today have the bow window cut out quite a long
way from the centre of the handle; this is done to ensure that you have
the best possible arrow clearance. If you do shoot with a stick on arrow
rest like the Hoyt Super Pro be sure to use the double sided tape with the
additional padding otherwise the rest will be too close to the bow handle.
Set up with an
arrow rest and pressure button
The
pressure button is a device that can absorb some of the archer’s paradox
and give some forgiveness for a bad release; it is also one of the most
useful items you can attach to your bow for fine-tuning, which we will
cover in detail in part two.
If
you decide to go with an adjustable magnetic rest, or a stick on flipper/
Hoyt Super Pro rest and pressure button from day one you will need to make
the following checks and adjustments.
Firstly,
if you are using a Hoyt Super Pro rest make sure you cut off the small
piece of plastic sticking out above the rest as this acts as a simple
button and will interfere with these adjustments.
With
a stick on rest you are limited to attaching it to the bow and ensuring
that the arm of the rest is long enough to rest the arrow on when you have
set the pressure button.
The
adjustable magnetic rest needs to be adjusted so that the arm only sticks
out a few millimetres from the arrow and the centre of the arrow is
touching the centre of the button. The arm should be set to allow it to
move towards the bow and return freely to the set position.
Finally,
you will notice that the pressure button is sprung, for now you need to
set it to its middle position roughly to about 12-15oz of pressure, you do
this by turning the screw on the end clockwise to increase and anti
clockwise to decrease the spring tension. There is a grub screw on the
side of the button, which needs to be slackened off, and re tightened when
completed.
8)
Time to go out and practice
That’s
all there is to it you have now finished setting up your bow, the
adjustments you have made are not perfect but good enough to allow you to
go out and shoot and start perfecting your shooting form. In part two we
will take the bow set up a stage further, but remember even a bow set up
as described here will in more experienced hands shoot more accurately
than you can at this stage, so unless something breaks don’t be tempted
to start fiddling.
Copyright Bow
International Magazine (2006) No reproduction is
permitted of any of the material published above without prior consent of
Bow International in writing.
Bow International:
Archery stories, News & Information from Great Britain and across the
world.
Part 2 of Bow tuning
was published in issue 38, Setting up of a button, Checking and changing
the Bracing height, Sight adjustments, How to do Bare Shaft and Walk back
tests and what the patterns really mean.
Latest editions and back issues available
shops and online shop here.
For a
link to direct subscriptions click
here
FINALLY,
THE GOOD NEWS IF ALL THE ABOVE INFORMATION SEEMS A BIT DAUNTING:
AT
THE TIME OF PURCHASE (Bow, limbs and accessories) WE WILL SET UP YOUR NEW
BOW AS DESCRIBED ABOVE AS PART OF OUR SERVICE (unless you say otherwise)
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