ASTM F1832-97(2002)
(Test Method)Standard Test Method for Determining the Force-Draw and Let-Down Curves for Archery Bows
Standard Test Method for Determining the Force-Draw and Let-Down Curves for Archery Bows
SCOPE
1.1 This test method covers the procedure to be used to determine the force-draw and let-down curves for archery bows.
1.2 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are for information only.
1.3 This standard does not purport all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.
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An American National Standard
Designation:F1832–97 (Reapproved 2002)
Standard Test Method for
Determining the Force-Draw and Let-Down Curves for
Archery Bows
This standard is issued under the fixed designation F 1832; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.1.4 draw—to move the shooting string of a bow from the
rest or braced position toward the full drawn position by
1.1 This test method covers the procedure to be used to
applying force to said string. Such action causes the limbs of
determine the force-draw and let-down curves for archery
thebowtobendandstoreenergy.Movingthestringfrombrace
bows.
height to the full draw position corresponds to the draw stroke
1.2 The values stated in inch-pound units are to be regarded
of a bow.
as the standard. The SI units given in parentheses are for
2.1.5 draw cycle—the combination of the draw-stroke and
information only.
the power-stroke, resulting in a full cycle from brace height to
1.3 This standard does not purport all of the safety con-
full draw and return to brace height.
cerns, if any, associated with its use. It is the responsibility of
2.1.6 draw-stroke—the distance in inches (millimeters)
the user of this standard to establish appropriate safety and
from brace height to full draw.
health practices, and determine the applicability of regulatory
2.1.7 force-draw curve—the curve that is plotted using the
limitations prior to use.
force readings, taken at incremental values of draw length
2. Terminology when drawing the bow, as the ordinate and the corresponding
draw length as abscissa.
2.1 Definitions of Terms Specific to This Standard:
2.1.8 full draw—the position assumed by the bowstring
2.1.1 AMO (archery manufacturers and merchants organi-
when the bow is drawn to a draw length corresponding to that
zation) draw length—the perpendicular distance from the point
from which it will be released for the shot. For most standard
where the shooting string of the bow contacts bottom of the
test purposes full draw is specified as 30 in. (762 mm) AMO
nock slot of the arrow, to a vertical line through the pivot or
draw length for compound bows, and 28 in. (711.2 mm)AMO
low point of the hand grip (draw length pivot point), plus a
draw length for non-compound bows, but it can take any
standard dimension of 1 3/4 in. (44.5 mm).
assigned value.
2.1.2 brace height—the dimension in inches (millimetres),
2.1.9 let-down curve—curve that is plotted using the force
from the grip pivot point (low point) of the grip to the nearest
readings, taken at incremental values of draw length when
side of the bowstring, measured perpendicular to the bow-
relaxing the bow, as the ordinate and the corresponding draw
string, with the bow strung and in the undrawn condition.
length as abscissa.
2.1.3 compound bow—a type of bow that imposes a sec-
2.1.10 let-off—thedifferencebetweenthepeakormaximum
ondarysystemofcontroloftheforce-drawcharacteristiconthe
draw force reached during the draw stroke of a bow, and the
usual limb geometry control system of the conventional bow.
lowest level of draw force reached subsequent to that peak.
Thissecondarycontrolsystemcanbecomposedofcam,levers,
Quantitatively, it is most frequently expressed as a percentage
cables, or other elements, and combinations thereof. The dual
of the peak force and is then referred to as percent of let-off.
control system permits great versatility in the design of the
2.1.11 non-compound bow—a bow constructed in the tradi-
force-draw characteristic, and simplifies the inclusion of let-
tional manner, having two flexing limbs extending outwardly
off. In general, it is normal for compound bows to have greater
inoppositedirectionsfromahandle.Asingleshootingstringof
stored energy than conventional bows for a given level of peak
a length shorter than the bow, connects the extreme ends of the
or maximum draw weight.
limbs causing them to assume a pre-stressed flexed condition.
Drawing the bow causes additional bending and stressing of
This test method is under the jurisdiction of ASTM Committee F08 on Sports
the limbs, storing the energy necessary to propel the arrow.
Equipment and Facilities and is the direct responsibility of Subcommittee F08.16 on
Control of the force-draw characteristic of the bow is exercised
Archery Products.
entirely by the static and dynamic geometry of the flexing
Current edition approved Nov. 10, 1997. Published August 1998. Originally
approved in 1997. Last previous edition approved in 1997 as F 1832 – 97. limbs and the bowstring.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1832–97 (2002)
2.1.12 peak draw force—the maximum force reached when 4.3 Draw Length Scale—A graduated scale at least 36 in.
drawing a bow. For conventional bows, the peak draw force is (914.4 mm) in length having commercial accuracy shall be
usually reached at the full draw condition. For compound used to measure the draw length. It shall be indexed at a point
bows, the peak draw force is reached part way through the 1 3/4 in. (44.5 mm) forward of the low point or pivot point of
draw, usually from about 35 to 75 % of the length of the draw the grip.
stroke.
2.1.13 power-stroke—the distance in inches (millimetres)
5. Procedure
from full draw to brace height.
5.1 Adjust the bow to the desired peak draw force and draw
2.1.14 static hysteresis—The difference in pounds (new-
length. On most conventional bows it will not be possible to
tons), measured under static conditions, between the draw
adjust draw force and draw length, however the bowstring
force and the let-down force for any given draw length.
length
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