ASTM F1832-07
(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
SIGNIFICANCE AND USE
This test method establishes the procedure to be used to measure the force necessary to draw an archery bow from brace height to the full draw position, and the holding force necessary to retain the bow string when the bow is let-down from full draw to brace height. The force values taken at increments of draw length are then plotted versus draw length using rectangular coordinates. The resulting curves are known as the force-draw curve and the let-down curve.
The force-draw curve is used to determine the energy that the limbs of the bow store when it is drawn. The area under the curve between the positions of brace height and full draw can be expressed as stored energy.
The let-down curve is used to determine the energy required to restrain the bowstring as the bow is let-down from full draw to brace height. The energy represented by the area under the curve can be subtracted from the stored energy in order to establish the static hysteresis of the bow system.
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:F1832–07
Standard Test Method for
Determining the Force-Draw and Let-Down Curves for
1
Archery Bows
This standard is issued under the fixed designation F1832; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.1.4 draw, v—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.
determine the force-draw and let-down curves for archery
2.1.4.1 Discussion—Such action causes the limbs of the
bows.
bow to bend and store energy. Moving the string from brace
1.2 The values stated in inch-pound units are to be regarded
height to the full draw position corresponds to the draw stroke
as the standard. The SI units given in parentheses are for
of a bow.
information only.
2.1.5 draw cycle, n—combination of the draw-stroke and
1.3 This standard does not purport all of the safety con-
the let-down stroke, resulting in a full cycle from brace height
cerns, if any, associated with its use. It is the responsibility of
to full draw and return to brace height.
the user of this standard to establish appropriate safety and
2.1.6 draw-stroke, n—distance in inches (millimeters) from
health practices, and determine the applicability of regulatory
brace height to full draw.
limitations prior to use.
2.1.7 force-draw curve, n—curve that is plotted using the
2. Terminology force readings, taken at incremental values of draw length
when drawing the bow, as the ordinate and the corresponding
2.1 Definitions of Terms Specific to This Standard:
draw length as abscissa.
2.1.1 ATA (archery trade association) draw length,
2.1.8 full draw, n—positionassumedbythebowstringwhen
n—perpendicular distance from the point where the shooting
the bow is drawn to a draw length corresponding to that from
string of the bow contacts bottom of the nock slot of the arrow,
which it will be released for the shot.
to a vertical line through the pivot or low point of the hand grip
3 2.1.8.1 Discussion—For most standard test purposes full
(draw length pivot point), plus a standard dimension of 1 ⁄4 in.
draw is specified as 30 in. (762 mm) ATA draw length for
(44.5 mm).
compound bows, and 28 in. (711.2 mm) ATA draw length for
2.1.2 brace height, n—dimension in inches (millimetres),
non-compound bows, but it can take any assigned value.
from the grip pivot point (low point) of the grip to the nearest
2.1.9 let-down curve, n—curve that is plotted using the
side of the bowstring, measured perpendicular to the bow-
force readings, taken at incremental values of draw length
string, with the bow strung and in the undrawn condition.
when relaxing the bow, as the ordinate and the corresponding
2.1.3 compound bow, n—type of bow that imposes a sec-
draw length as abscissa.
ondarysystemofcontroloftheforce-drawcharacteristiconthe
2.1.10 let-off, n—difference between the peak or maximum
usual limb geometry control system of the conventional bow.
draw force reached during the draw stroke of a bow, and the
2.1.3.1 Discussion—This secondary control system can be
lowest level of draw force reached subsequent to that peak.
composed of cam, levers, cables, or other elements, and
2.1.10.1 Discussion—Quantitatively, it is most frequently
combinations thereof. The dual control system permits great
expressed as a percentage of the peak force and is then referred
versatility in the design of the force-draw characteristic, and
to as percent of let-off.
simplifies the inclusion of let-off. In general, it is normal for
2.1.11 non-compound bow, n—bow constructed in the tra-
compound bows to have greater stored energy than conven-
ditional manner, having two flexing limbs extending outwardly
tionalbowsforagivenlevelofpeakormaximumdrawweight.
in opposite directions from a handle.
2.1.11.1 Discussion—A single shooting string of a length
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This test method is under the jurisdiction of ASTM Committee F08 onSports
shorter than the bow, connects the extreme ends of the limbs
Equipment and Facilities and is the direct responsibility of Subcommittee F08.16 on
Archery Products. causing them to assume a pre-stressed flexed condition. Draw-
Current edition approved Oct. 1, 2007. Published November 2007. Originally
ing the bow causes additional bending and stressing of the
approved in 1997. Last previous edition approved in 2002 as F1832 – 97 (2002).
limbs,storingtheenergynecessarytopropelthearrow.Control
DOI: 10.1520/F1832-07.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1942
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
An American National Standard
Designation:F1832–97 (Reapproved 2002) Designation:F1832–07
Standard Test Method for
Determining the Force-Draw and Let-Down Curves for
1
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
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.
2. Terminology
2.1 Definitions of Terms Specific to This Standard:
2.1.1 AMOATA (archery manufacturers and merchants organization) trade association) draw length, n—the perpendicular
—perpendicular distance from the point where the shooting string of the bow contacts bottom of the nock slot of the arrow, to a
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vertical line through the pivot or low point of the hand grip (draw length pivot point), plus a standard dimension of 1 3/4 ⁄4 in.
(44.5 mm).
2.1.2 brace height—the dimension, n—dimension in inches (millimetres), from the grip pivot point (low point) of the grip to
the nearest side of the bowstring, measured perpendicular to the bowstring, with the bow strung and in the undrawn condition.
2.1.3 compound bow, n—a type —type of bow that imposes a secondary system of control of the force-draw characteristic on
the usual limb geometry control system of the conventional bow.
2.1.3.1 Discussion—This secondary control system can be composed of cam, levers, cables, or other elements, and
combinationsthereof.Thedualcontrolsystempermitsgreatversatilityinthedesignoftheforce-drawcharacteristic,andsimplifies
the inclusion of let-off. In general, it is normal for compound bows to have greater stored energy than conventional bows for a
given level of peak or maximum draw weight.
2.1.4 draw, v—to move the shooting string of a bow from the rest or braced position toward the full drawn position by applying
force to said string.
2.1.4.1 Discussion—Such action causes the limbs of the bow to bend and store energy. Moving the string from brace height to
the full draw position corresponds to the draw stroke of a bow.
2.1.5 draw cycle, n—thecombination—combinationofthedraw-strokeandthepower-stroke,let-downstroke,resultinginafull
cycle from brace height to full draw and return to brace height.
2.1.6 draw-stroke—the distance, n—distance in inches (millimeters) from brace height to full draw.
2.1.7 force-draw curve—the curve, n—curve that is plotted using the force readings, taken at incremental values of draw length
when drawing the bow, as the ordinate and the corresponding draw length as abscissa.
2.1.8 full draw, n—the position —position assumed by the bowstring when the bow is drawn to a draw length corresponding
to that from which it will be released for the shot.
2.1.8.1 Discussion—For most standard test purposes full draw is specified as 30 in. (762 mm) AMOATA draw length for
compound bows, and 28 in. (711.2 mm) AMOATA draw length for non-compound bows, but it can take any assigned value.
2.1.9 let-down curvelet-downcurve, n—curvethatisplottedusingtheforcereadings,takenatincrementalvaluesofdrawlength
when relaxing the bow, as the ordinate and the corresponding draw length as abscissa.
2.1.10 let-off, n—thedifference—differencebetweenthepeakormaximumdrawforcereachedduringthedrawstrokeofabow,
and the lowest level of draw force reached subsequent to that peak.
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ThistestmethodisunderthejurisdictionofASTMCommitteeF08onSportsEquipmentandFacilitiesandisthedirectresponsibilityofSubcommitteeF08.16onArchery
Products.
Current edition approved Nov. 10, 1997. Published August 1998. Originally approved in 1997. Last previous edition approved in 1997 as F1832 – 97.
Current edition approved Oct. 1, 2007. Published November 2007. Originally approved in 1997. Last previous edition approved in 2002 as F 1832 – 97 (2002).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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