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Last-modified: 23 March 1994
Written by: Stephan Melin (Stephan.Melin@neuss.netsurf.de)
by Stephan Melin (Stephan.Melin@neuss.netsurf.de)
Comments, flames etc. directly to me...
(should be valid for all types of bows and shooting styles)
(only for bows with a cushion plunger)
(mainly for archers using a mechanical release)
Because the subject of tuning the bow is still a bit controversial, I will give you my philosophy (which I also apply on shooting style):
IMPORTANT NOTE IMPORTANT NOTE IMPORTANT NOTE IMPORTANT NOTE IMPORTANT NOTE
In section A and B I sometimes write something like: "Shoot an arrow..."
This sloppy writing could be somewhat confusing, what I mean is that one should shoot a couple of arrows and determine the centre of the group.
IMPORTANT NOTE IMPORTANT NOTE IMPORTANT NOTE IMPORTANT NOTE IMPORTANT NOTE
Most of the stuff should be valid for all types of bows (longbow, target recurve, compound), all types of arrows with target or field points or broadheads and for finger as well as for mechanical release shooters. It is assumed that one starts with an arrow which is not totally wrong for the bow (look into the arrow selection charts of the manufacturers!) Everthing else like the string length for example should be set to a reasonable value (maybe you use the recommended values from the manufacturer...). If you don't have a cushion plunger just ignore the remarks about the plunger. If you have an adjustable rest you can apply the remarks for the plunger.
While the paper tuning test might help you to tune your compound shot with a mechnical release it might be somewhat misleading when used only for a single distance as all other single distance "tuning" methods. All those methods have a major drawback: they will help you to setup your bow that it is tuned for this distance, but for any other distance it might be completely detuned. The method described here overcomes this drawback by shooting at different distances and works for all types of bows and shooting styles.
The distances given in the following method are just a suggestion.
Get a ruler, a pen, a fletched arrow and an unfletched arrow (same spine, point, length, etc.) which are _PERFECTLY STRAIGHT_ (read: new arrows).
Make a target face which looks like this (take the back of the biggest target face available and make this drawing as big as possible):
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------------#-----------
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You should always aim at the # in the middle of this cross.
Now make several blank diagrams like this:
30m -------+----+----+------
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27m -------+----+----+------
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24m -------+----+----+------
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21m -------+----+----+------
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18m -------+----+----+------
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15m -------+----+----+------
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12m -------+----+----+------
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9m -------+----+----+------
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6m -------+----+----+------
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3m -------+----+----+------
-7 0 7
The x axis gives the distance in cm of the arrow from the horizontal or vertical (this depends from what you are tuning) centerline.
Set the sight to approximately 30m (if you are a barebow archer, just remember to aim always in the same way as if the target were 30m away - regardless how far it is away).
Everything which I describe is valid for a right hand archer (the arrow is on the left side of the bow if one looks from behind) - for a left handarcher it is the opposite...
Shoot a few fletched arrows at the target and look where the group goes. If it is left from the centre increase the spring tension, if right decrease the tension. Repeat this procedure until the group is at the centre.
The spring tension should be in the intermediate region. If it is much too weak the arrow is way to stiff, if it is much too strong the arrow might be not stiff enough, in this case you could try moving the position of the cushion plunger head a little bit left and decrease the tension, then repeat step 1 until the group is in the centre.
The line for the fletched arrow should always be near the 0 line (if not, look at step 4). Now look at the line for the unfletched arrow. If the arrow is ok, it should be more or less parallel to the line for the fletched arrow and you are done with the tuning.
Here are a few deviation patterns:
O denotes the unfletched arrow
X denotes the fletched arrow
* denotes both on the same spot
30m -------+----X----+------
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27m -------+---X+----+------
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24m -------+---X+----+------
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21m -------+----+-X--+------
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18m -------+----+X---+------O
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15m -------+----+-X-O+------
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12m -------+---XO----+------
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9m -------+--OX+----+------
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6m -------+-OX-+----+------
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3m -------+--*-+----+------
-7 0 7
It starts to deviate at distances less than 15m:
This means the arrow is not stiff enough - get the next stiffer one.If it deviates to the left, it is too stiff - get the next less stiff one.
30m -------+----X----+------
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27m -------+---X+----+-----O
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24m -------+--X-+---O+------
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21m -------+----*----+------
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18m -------+-O--+-X--+------
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15m -------O----X----+------
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12m ------O+-X--+----+------
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9m -------O--X-+----+------
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6m -------+-OX-+----+------
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3m -------+--OX+----+------
-7 0 7
It starts to deviate at distances greater than 15m:
The arrow is not stiff enough - cut it a little and/or get a lighter point. If it deviates to the left, it is too stiff - get a heavier point and/or choose a longer one.
If both lines intersect: your setup of the cushion plunger is wrong...
30m -------+---X+O---+------
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27m -------+----*----+------
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24m -------+---OX----+-----
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21m -------+--OX+----+------
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18m -------+---XO----+------
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15m -------+----XO---+------
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12m -------+----OX---+------
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9m -------+---X+O---+------
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6m -------+----XO---+------
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3m -------+----+*---+------
-7 0 7
The setup is OK.
30m -------+----+X--O+------
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27m -------+--X-+--O-+------
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24m -------+OX--+----+------
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21m -------+----+-X-O+------
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18m -------+--X-+O---+------
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15m -------+--O-X----+------
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12m -------+----+-XO-+------
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9m -------+--OX+----+------
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6m -------+---O+X---+------
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3m -------+---X+O---+------
-7 0 7
Although within the tolerances, you might want to change something in your setup: use a heavier arrow, adjust the cushion plunger, change the string length, change the stabilization...
How to interpret the curves:
30m -------+----+X--O+------
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27m -------+--X-+--O-+------
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24m -------+OX--+----+------
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21m -------+----+-X-O+------
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18m -------+--X-+O---+------
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15m -------+--O-X----+------
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12m -------+----+-XO-+------
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9m -------+--OX+----+------
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6m -------+---O+X---+------
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3m -------+---X+O---+------
-7 0 7
Both curves are parallel - the nocking point is OK.
30m -------+----+--X-+------
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27m -------+----X----+------
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24m -------+-X--+----+------
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21m ------X+----+----+--O---
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18m -----X-+----+--O-+------
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15m ------X+----+O---+------
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12m -------X----O----+------
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9m -------+-X--+O---+------
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6m -------+---X+-O--+------
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3m -------+----+X-O-+------
-7 0 7
The nocking point is too high.
30m -------+----+---X+------
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27m -------+----X----+------
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24m -------+-X--+----+------
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21m -------X----+----+------
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18m O ------X+----+----+------
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15m --O---X+----+----+------
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12m -----O-X----+----+------
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9m -------+OX--+----+------
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6m -------+--OX+----+------
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3m -------+----OX---+------
-7 0 7
If you can read german, this is very nice little book about tuning and a few other aspects about practise and tournaments.
This step can be skipped if you everything went fine with the method of section A. It also can be used for a quick retuning of the bow.
Here you only need to use fletched arrows. Shoot the arrows at the different distances and measure the HORIZONTAL deviation from the VERTICAL line. Fill these points into your chart.
Everything is for a right handed archer, left handed archers should invert all advice.
If it looks like this:
30m X
X
X
X
X
X
X
3m X
move the head of the plunger a little in the right direction until it becomes a straight line. If the curve is oriented in the other direction move the head of the plunger a little to the left. Repeat this procedure until you get a straight line.
If the line looks like this:
30m X
X
X
X
X
X
X
3m X
decrease the spring tension until the line is perfectly vertical. If the line is oriented in the other direction increase the spring tension...
The method I describe here should work best, when using a mechanical release - however I am willing to accept otherwise.
Put a sheet of paper into frame and fix this frame in front of sufficient back stop - but far enough away so that the arrow can pass through completly.
Now start at about 1m (0.9m = 1 yard) distance from the paper and shoot your arrow at the paper.
Inspect the hole it made, the advice given is for a right handed archer, the left handed ones should invert the advice where appropiate:
#
*
*
*
*
*
#
/ \ <- these are the vanes
/ \
/ \
your nocking point is too low
\ /
\ /
\ /
#
*
*
*
*
*
#
your nocking point is too high
\
\
#******#
/
/
either the arrow is too soft, or the spring tension of the cushion-plunger should be increased (left handed archers)
/
/
#******#
\
\
either the arrow is too stiff, or the spring tension of the cushion-plunger should be decreased
Of course any combination of 1 and 2 can occur.
Repeat until the hole looks like this:
\ /
\ /
\ /
#
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Now the arrow is perfect for this distance.
This test should be repeated in about 1m steps until 5m distance from the paper. If everything is ok, repeat these tests on a larger distance - until you find the best compromise.
As ever: mail your comments to Stephan Melin (Stephan.Melin@neuss.netsurf.de)
I would be happy to get some feedback, especially if you have the tuning method which improves the scores by at least 1 point :-)
This is a section of the FAQ for alt.archery. It is maintained by me at the following e-mail address: trier@pilot.msu.edu Comments, flames, etc. on the FAQ are welcome and should be directed to me. Comments on the specifics of the section can be addressed to either me or the person responsible for this section. If addressed to me, I will forward them to the author of the section. If you wish to see this section cross-posted to another group, please e-mail me a request to do so. If I can access that group, then I will so cross-post whenever I post this section.
Terry Trier trier@pilot.msu.edu
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Wrapped on 9th March 1997 by angus@harlequin.co.uk