Published by archerchick on 17 Feb 2011 at 05:21 pm
Let’s Make The American Flat Bow~ By Pierre St. Arnaud
THE FLAT BOW began to appear on American
tournament lines about 1932. Prior to this, the English
longbow for centuries had been virtually the only type in
The transition from longbow to flat bow was due, in the
main, to efforts to improve bow designs by such archer-
scientists as Dr. Paul E. Klopsteg, Dr. Clarence N. Hickman,
and Forest Nagler. These men, physicists and engineers,
circumvented tradition and applied engineering principles
to the designing of bows. The application of these principles
resulted in a bow of rectangular cross section.
To understand why the longbow with stacked cross
section is functionally inferior to the bow of rectangular
cross section, refer to plate 1, types of cross sections. Let’s
consider a longbow being bent. The cross-sectional shape of
the longbow limb is narrow, thick and rounded on the belly
side. The belly C is the compression side and the back T is
the tension side.
The neutral or shearing axis N bisects the mass of the
section. In the longbow, the shearing plane is farther from
the belly than from the back. This condition imposes excessive
stress at the belly. The farther the fibers are from
the shearing plane, the greater are the compressive stresses
at the belly, and the belly overworks, and the back underworks.
To circumvent this design, and to prevent breakage
due to compression failure, the bow must be made long to
give a large radius of bend.
Refer to the sections for the semi-flat bow and the flat
bow. The neutral or shearing plane runs equidistant
from the back and the belly in these designs. All parts work
equally, and these bows are more efficient. They can be
made shorter than the longbow for the same arrow draw.
Now, let’s get on to the designing and constructing of
the flat bow. This bow is made more easily than the long-
bow. Those of you who have made the longbow will find
the same methods applicable to making the flat bow.
First, let’s consider the woods which can be used.
Lemonwood or dagame, a semi-tropical wood, is a good
choice. It is a good compression wood and can be used with
no regard to grain. Yew and Osage orange make excellent
bows, but let’s save these woods for a future article. They
require special treatment. Pignut hickory is high in tensile
strength and makes a tough, serviceable bow. It is good for
backing other bow woods, and it takes to hot bending
White ash is another tough, elastic wood that takes
readily to hot bending. Black walnut makes a bow of quick
cast but must be backed with hickory. Greenheart, another
tropical wood, is high in compression strength. It varies in
color from light green to nearly black. Purpleheart
(amaranth) is a deep purple color and is also a tropical
There are many other woods with which bows can be
made, but the above mentioned offer a good selection. All
of the above woods should be air seasoned for use in
bowyery. Kiln-dried wood is brash and does not yield well.
Some of these woods can be bought to your dimensional
specifications from the following dealers: Craftsman Wood
Service Company, Department BA, 2729 South Mary,
Chicago, Illinois 60608; Constantine, Dept. BA, 2051-C
Eastchester Road, Bronx, New York 10461.
You will need the following tools and materials: a low
anglerblock plane, a ten or twelve-inch half-round cabinet
file; a three by_five-inch square cabinet scraper; a six-inch
rat tail file; garnet paper, medium and fine; and a
fifty-pound spring scale.
Lemonwood is so dense and close-grained you need not
concern yourself with flat or edge grain. If you use the
other woods, order your staves flat grained. The cross
section S shown in plate 1 shows how grain should run in
your stave and B denotes the side which is to be the back of
The stave dimensions are 65 x 1% x 5/8. Smooth the
back of the stave with a plane and medium garnet paper.
Measure your stave from end to end and mark the exact
middle. Scribe lines completely around all four sides at this
The ten-inch handle riser will bisect this line on the
belly. The riser must be flat-grained hardwood, walnut,
maple or oak and will be ten inches long by 1% inches (the
width of the stave) by one-inch.
The riser is glued directly over the middle of the stave
with equal lengths of riser to each side of the middle mark
on the stave. Be certain the riser is glued to belly side of the
Both surfaces of the glue joint must be planed square
and flat, or a poor joint will result, and the riser will pop
off. When gluing risers, use any of the following types of
glue: urea resin, resorcinol or casein. The white polyvinyl
glue creeps under stress. Be certain to read the directions on
the container for the glue used.
Apply the glue to both surfaces and center the riser on
the stave. Three three-inch C-clamps are used — one at the
middle of the riser and one about one-inch from each end.
Use small pads of wood under the clamps to prevent
marring the bow. Be careful to keep the riser from shifting;
snug up the middle clamp, then snug up the other clamps.
Proceed to tighten until you get squeeze-out glue along the
edges of the joint. Allow this assemblage to dry for a least
twenty-four hours before further progression.
If C-clamps aren’t available, wrap the riser to the stave
with one-inch wide rubber strips cut from an inner tube.
Stretch the rubber tightly to insure sufficient pressure.
After removing the clamps, clean the squeezed-out
hardened glue from the stave with a file. Lay the stave with
the back up on your work bench. Refer to bow dimensions
in plate 1.
At stations A, five inches from the middle of the stave,
scribe marks across the stave. Measuring from the side edges
of the stave, place dots at the middle of lines A. Attach
small weights to the ends of a stout thread about a foot
longer than the stave. Allowing the weights to hang freely,
bisect the dots at points A. Place additional dots a few
inches apart under the thread along the full length of the
the stave. Connect these dots with a straight edge. This line
is your datum line.
Referring to the diagram, lay out the mid-part of the
bow. The arrow rest R can be transferred to the opposite
side of the stave if you are left-handed. At one-half-inch
from the ends of the stave, station E, mark out one-half-
inch for width. From these dots, straight edge lines to the
full width of the stave at station A. Both limbs are of equal
length in this design and differ from the longbow with its
longer upper limb.
The back is now laid out. Bandsaw or hacksaw the stave
to shape. Stay a little bit away from the lines when sawing.
After sawing, work just to the lines with a plane and file,
being sure to keep the sides square, ninety degrees to the
back. This completes the contouring of the back.
Lay the stave with one side up on your bench. Lay out
the grip. If a saddle grip is wanted, lay it out as shown by
the dotted line. Do not make the bottom of the saddle too
deep, or you will weaken the bow at this point. If a deep
saddle or a straight wrist grip is desired, glue a thicker riser
to the stave. The dips are three inches long. Go to station A
on the side of the bow limb. From the back to the belly,
measure one—half-inch for your base limb thickness. From
this dot, scribe the dip to the top of the riser. The bottom
of the dip should curve gradually and become more abrupt
as it approaches the top of the grip.
Beginning from station A, measure 6-% inches to station B
and follow the diagram markings to E. Mark a 15/32-inch
thickness at station B, 7/ l6—inch at C, and again follow the
diagram to station E. Join these dots to establish the
thickness taper. Repeat this procedure on the three remain-
ing sides of the limbs. Plane and file down to the lines, and
leave the rest for tillering. The dips are sawed and filed
carefully, so the bottom of each dip feathers smoothly into
the base limb.
Place a tip of the bow against the floor, belly side to-
ward you, and exert pressure against the grips with the right
hand while holding the uppermost limb with the left. Deflect
the lower limb only a little, while judging the amount
of resistance or stiffness and examine the limb to see if it
bends evenly. Repeat with the other limb.
If both limbs seem to balance with each other, you are
ready to cut your nocks and string the bow. If there is an
imbalance, mark the stiff spots on the belly with a pencil
and scrape these spots down, checking the bend and resistance
frequently until all seems to be in balance.
Refer to nock details in plate 1. Use the six-inch rat tail
and cut into the sides at station E. Go into the wood about
one-eighth of an inch and diminish this cut into the belly as
you slant at the angle shown. If you want to use overlays to
enhance the appearance of your bow, glue hardwood blocks
to the tips as shown in plate 1. The shaded area in the
diagram shows the amount of wood to be cut and tiled
away leaving the tip shaped as shown.
When overlays are used, the nocks are cut into the back
as well as into the sides. Otherwise do not cut into the
back, because doing so will weaken the tip. String the bow
to a seven-inch brace, measuring from the back of the grip
to the string. Use a stout string for tillering.
Examine the strung bow for stiff spots and uneven
bending. Both limbs must bend evenly. Mark and scrape all
stiff spots. If one limb is too stiff, scrape it down to match
the other in curvature. When the bow balances at this stage,
you are ready to use the tiller. Use 36 x 2 x 1%-inch stock.
Cut a notch at one end to accept the bow grip. Along one
edge, measuring twelve inches from the grip notch, cut a
series of string grooves two inches apart to a location
twenty-eight inches from the grip notch. Refer to plate 1.
Fit the center of the grip into the notch of the tiller, and
slip the string into the twelve-inch groove. Place the bow on
your bench with the tiller uppermost, and step back to
examine the bend.
Mark any stiff spots, and remove the string and scrape
down. Put the bow back in the tiller at the twelve-inch
groove and re-examine. The bend of each limb should start
at the bottom of the dip and curve in a gradual, graceful
curve to the tip with no stiff areas. Both limbs should bend
Work your way up to the twenty-eight-inch groove in
this manner. Be cautious when you get to the twenty-four-
inch groove. From this draw to full draw, do not leave the
bow on the tiller for more than a few seconds. Any imbalance
can cause the bow to break while under great stress.
Shape the grip as shown in plate 1, Gc. Round off all the
edges of the bow slightly as shown in the flat bow cross-
Attach a large steel screw hook to a stud in the garage
about six inches from the floor. Hang the spring scale from
this hook. Bore a hole in the end of a yardstick, and hang
the stick on the scale hook. With the nocking point of the
string on the scale hook, draw the bow down to twenty-
eight inches and read the scale.
Sand the bow smooth, starting with medium and
finishing with fine garnet. Whisker the bow. Rub it with a
damp cloth. When dry, the whiskery ends of grain will be
left standing. Steel wool the whiskers off with 2/0 wool.
Mix a one-to—one solution of spar varnish and turpentine,
and apply this liberally to the bow. After twenty minutes,
wipe all the mixture from the bow with a clean, dry rag.
Let this dry for twenty-four hours, and apply the finish
coat full strength. The grip can be covered with leather or
heavy colored fish cord.
The flat bow can be recurved. There are two methods of
recurving, laminating and steaming or boiling. I will explain
here the process of boiling or hot bending. Lay out a board
16 x 4 x 1 3/4 inches as shown in A, plate 2. Be certain the
working or top edge is ninety degrees to the sides. Attach a
strap-iron stirrup and stop block as shown.
Leave enough room in the stirrup to accept the bow end,
the support strip, and wooden wedge. A straight—limbed
recurved bow is more highly stressed than a straight bow if
both are the same length. It is advisable to lengthen the
recurved bow. This is done by extending the distances between
stations A, B, C, D and E to 7% inches. This will
result in a sixty-eight-inch bow, measuring between the
To prepare the bow for recurving, work it down to
dimensions as you would the straight bow, but do not cut
the nocks. Using stout cord, wrap a twelve-inch strip of
fiber to the belly of the bow on the end to be boiled. Keep
the wraps very close. A length of .02-inch metal strap can
be used in place of the fibre. The strap prevents spills from
raising during bending. Fill a large bucket or can with hot
water, and place the bow end into the water. Bring the
water to a boil and continue to boil. for 1% hours. Replenish
the evaporated water with more boiling water from
another receptacle. If you add cold water, the bow cools,
and the boiling process must be begun all over again.
When the end has boiled sufficiently, remove it quickly
from the bucket, and insert it into the stirrup of the form.
Tap the wedge firmly into place, and bend the limb into
place on the form. Clamp it down with a C-clamp through
the hole in the end of the form. Be sure the tip is centered
in the stirrup to avoid twist. This operation must be done
quickly to prevent the bow’s cooling. Wrap the whole
assembly with one-inch wide rubber strips cut from an
innertube. Stretch the rubber tight as you wrap.
Let the bow end cure in the form for two days before
removing it. Recurve the other end and cure. Refer to re-
curve groove and nock detail in plate 2 The groove along
the top of the recurve retains the string. The grooves and
nocks are cut after the bow has been tested against the
floor for proper bend.
After cutting the nocks, string the bow, and mark out
the grooves along both sides of the string. The end of the
groove should end at the point where the string ceases con-
tact with the recurve. The bow is tillered and finished like a
The English longbow is not adaptable to recurving; the
tip overlay can be used with the recurve; aluminum foil
wrapped around the .02 metal strap before boiling will prevent
rust stains; the string for a recurved bow will be
shorter than one for an equal length straight bow. <——<<
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