ASTM F1880-98(2004)

Standard Test Method for the Determination of Percent of Let-Off for Archery Bows

ABSTRACT
This test method covers procedure to determine the percent of let-off for archery bows. Percent of let-off shall be determined from formula using force-draw curve. Other factors for percent of let-off determination include hysteresis effect and rating conditions.
SCOPE
1.1 This test method establishes the procedure to be used to determine the percent of let-off for archery bows.  
1.2 This standard does not purport to address 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.

General Information

• Status: Historical
• Publication Date: 30-Apr-2004
• ICS: 97.220.40 - Outdoor and water sports equipment
• Technical Committee: F08 - Sports Equipment, Playing Surfaces, and Facilities
• Drafting Committee: F08.16 - Archery Products

Relations

• Replaces: ASTM F1880-98e1 - Standard Test Method for the Determination of Percent of Let-Off for Archery Bows
• Effective Date: 01-May-2004
• Replaced By: ASTM F1880-09 - Standard Test Method for the Determination of Percent of Let-Off for Archery Bows
• Effective Date: 01-Nov-2009

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
An American National Standard
Designation:F1880–98 (Reapproved 2004)
Standard Test Method for the
Determination of Percent of Let-Off for Archery Bows
This standard is issued under the fixed designation F1880; 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 3.1.4 compound bow, n—a type of bow that imposes a
secondary system of control of the force-draw characteristic on
1.1 This test method covers the procedure to be used to
the usual limb geometry control system of the conventional
determine the percent of let-off for archery bows.
bow. This secondary control system can be composed of cams,
1.2 This standard does not purport to address all of the
levers, cables, or other elements, or a combination thereof.The
safety concerns, if any, associated with its use. It is the
dualcontrolsystempermitsgreatversatilityinthedesignofthe
responsibility of the user of this standard to establish appro-
force-draw characteristic and simplifies the inclusion of let-off.
priate safety and health practices and determine the applica-
In general, it is normal for compound bows to have greater
bility of regulatory limitations prior to use.
stored energy than conventional bows for a given level of peak
2. Referenced Documents or maximum draw weight.
3.1.5 conventional bow, n—a bow constructed in the con-
2.1 ASTM Standards:
ventional manner, having two flexing limbs extending out-
F1832 Test Method for Determining the Force-Draw and
wardly in opposite directions from a handle.Asingle shooting
Let-Down Curves for Archery Bows
string of a length shorter than the bow, connects the extreme
3. Terminology
ends of the limbs causing them to assume a prestressed flexed
condition. Drawing the bow causes additional bending and
3.1 Definitions:
stressing of the limbs, storing the energy necessary to propel
3.1.1 ATA—an acronym for the Archery Trade Association.
the arrow. Control of the force-draw characteristic of the bow
3.1.2 ATA draw length, n—the perpendicular distance from
is exercised entirely by the static and dynamic geometry of the
the point where the shooting string of the bow contacts the
flexing limbs.
bottom of the nock slot of the arrow to a line parallel to the
3.1.6 draw, n—to move the shooting string of a bow from
stringatbraceheightthroughthepivotorlowpointofthehand
the rest or brace position toward the fully drawn position by
grip (draw length-pivot point), plus a standard dimension of
3 applying force to said string. Such action causes the limbs of
1 ⁄4 in. (44.5 mm). Draw length shall be measured with the
thebowtobendandstoreenergy.Movingthestringfrombrace
arrow in the full-draw position.
height to the full-draw position corresponds to the draw cycle
3.1.3 brace height, n—the distance in inches or millimetres
of a bow.
from the shooting string of a bow to the pivot or low point of
3.1.7 draw force, n—that level of force necessary and
the hand grip, measured perpendicular to the string.
coincidental with drawing a bow to a specific position within
its draw length.
This test method is under the jurisdiction of ASTM Committee F08 on Sports
3.1.8 force-draw curve, n—the curve obtained when the
Equipment and Facilities and is the direct responsibility of Subcommittee F08.16 on
draw force is plotted versus the draw length for a given bow.
Archery Products.
3.1.9 full draw, n—the position in a draw cycle of a bow
Current edition approved May 1, 2004. Published May 2004. Originally
´1
from which the string of the bow is released and the force
approved in 1998. Last pervious edition approved in 1998 as F1880 - 98 . DOI:
10.1520/F1880-98R04.
applied to the rear of the arrow to commence the launch. The
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
full-draw position of individual archers will vary due to
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
personal physical characteristics and shooting style. Archery
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. bows are specified as to the range of draw length that they will
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1880–98 (2004)
accommodate to permit archers to select a size that will fit obtainable (but not to exceed the maximum rated weight of the
them. Precise draw length is less of a factor on conventional bow) shall be used to determine the official percent of let-off
bows as compared with compound bows, since it is ideal to for the bow in question.
match the draw length of the archer to the position of
4.2 Historically, two methods have been in use to establish
maximum let-off in the draw cycle of the compound bow. The
the percent of let-off for archery bows. The most common
position of maximum let-off for compound bows usually is
method uses the peak draw force and the minimum holding
adjustable within specified limits.
force read from the force-draw curve to calculate the percent of
3.1.10 holding force, n—the force required to retain the
let-off. The second method uses the peak draw force from the
bowstring of a drawn bow at a specific draw length.
force-draw curve and the minimum holding force from the
3.1.11 let-down curve, n—the curve obtained when the
let-down for this calculation. This test method defines the two
force necessary to restrain the bow from returning to brace
methods and distinguishes between them.
height is plotted versus the draw length.
3.1.12 let-down force, n—the force required to retain the
5. Determination of the ATA Percent of Let-Off
bowstring of the drawn bow at a specific draw length during
5.1 Use of th
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