Measuring Traditional Bow String – The Right Way



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Measuring Traditional Bow String – The Right Way

By Marvin Long – President TailorMaid Archery Products

Sep 20, 2006 – 11:43:00 AM

 




For the Best in all your bowstring/cable needs: TailorMaid


Measuring Traditional Bows and Bowstrings

There is a lot of misconception about measuring bowstrings
for traditional (conventional) bows and I would like to help alleviate some of
the questions about these bows and bowstrings.

I have sat on the AMO (Archery Manufacturers Organization)
& ATA (Archery Trade Association) Specifications committee for some 20
years and have been involved in many discussions about archery equipment
specifications. I have also been manufacturing bowstrings commercially for 28
years. I made my first bowstring in Boy Scout Camp in 1954.

Recurve and Longbows are historic items that are now being
used more and more, which I am glad to see. Archers using the old style
equipment will help keep alive the history of our sport.

Ben Pearson, Earl Hoyt and Fred Bear and others that where
involved in our sport in the middle of the last century and earlier, under
stood there needed to be standards set for the industry to make it easier for
archers to enjoy the sport. Setting a standard for measuring the bow I am sure
was one of many and since the compound has become much more dominate in the
sport, many of the newer sport shop operators are not as familiar with the
traditional bows.

The Archery Trade Association (ATA) specifies that a
Traditional Bowstring should be labeled and sold by the length of the bow not
the bowstring length itself. A 60″ Bowstring is for a 60″ bow, not
the length of the bowstring. A Traditional bow is measured from string groove
to string groove around the curve of the bows limbs, not directly from tip to
tip. This measurement does not go into the curve of the handle but across the
face of the bow limbs from string groove to string grove. This will give you
the approximate length of the bow.

A Bowstring for bows over 40 lbs is measured by placing it over
steel pegs and stretching it at 100 lbs of tension for 20 seconds. The
measurement is taken from the outside of each peg. ATA Specs say that a bow
should be properly braced with a string that measures 3″ shorter than the
bow. So if a bow is 60″ is should be braced properly with a string
measuring 57″ under 100 lbs of tension after 20 seconds. Bowstrings for
bows of less than 40 lbs should be measured in the same manner, using 50 lbs of
tension.

Bow Makers used a Bowstring Master Set of steel cables that
would be designated as AMO (now ATA) Bow Lengths such as AMO 66″ (bow
length) but it would have an actual length of 63″ under 100 lbs of
tension. If this cable should brace a bow correctly it would be classified a 66″
bow. A Bowstring Master Set would range from 45″ to 69″ and would
brace bows from 48″ to 72″.

A Dacron Bowstring, which will stretch almost an inch under
100 lbs of tension, will look ?out of the package? like it is 4 inches shorter
than the bow. This is the reason you hear people speak about bowstrings being 4
inches shorter than the bow length. This will only be for a Dacron bowstring
and not under tension or actual length.

Because all materials stretch differently, measuring
everything under pressure compensates for the differences between materials.
The newer materials, like Fastflight do not stretch like Dacron, so they will
look longer out of the package and more like the three inches according to ATA
Standards. Strings are supposed to be measured with out any twist at that time.
However strings are installed with some twists to give better performance and
by twisting and archer can achieve better arrow flight. Some modern archers
shoot with as many as 50 twists in a 70″ bowstrings. To get the proper
length bowstring after twisting 50 twists you may have to start with a
bowstring 1″ longer.

Strings that have been shot a long time and need to be
changed will probably look longer than when they were new so going by the bow
length is a more consistent starting reference.

Strings can be twisted to change their length and this can
be done to change the bow set up so it performs better for each individual
archer. This will help get better flight characteristics for the arrow; this is
called tuning your setup or getting all parts working best together.

Marv Long measuring the Bear Grizzly AMO 58″, the ruler does not go into the handle but goes directly across the face of the limbs.


Shows the AMO 58″ bow measures 57″ from string groove to string grove


Show 4 bows of different ages. The left bow is marked AMO 58″ the next bow is marked 60″ and the remaining two are not marked for length. They are all Bear Archery Bows The 3rd bow is a static recurve wih the aluminum lamination and a running bear logo, The 4th bow is a laminated bow signed by Nel’s Grumley with no weight or length on it.


Shows the bow is marked as an AMO 58″ bow and this bow measures 57″ from string groove to strings groove but being an AMO St233andard it will brace properly with a 55″ AMO bowstring so it is a AMO 58″ bow.


All the non AMO marked bows do measure the length marked on the bow ie (60″ bow).

For the Best in all your bowstring/cable needs: TailorMaid

 
 

 

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