ASTM_F_1880_-_09_2013.pdf

Designation:F188009(Reapproved 2013)An American National StandardStandard Test Method for theDetermination of Percent of Let-Off for Archery Bows1This standard is issued under the fixed designation F1880;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the procedure to be used todetermine the percent of let-off for archery bows.1.2 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2F1832 Test Method for Determining the Force-Draw andLet-Down Curves for Archery Bows3.Terminology3.1 Acronyms:3.1.1 ATAArchery Trade Association3.2 Definitions:3.2.1 ATA actual draw length,ndistance from the bowsstring at the nocking point location,while at the bows fulldraw condition,measured perpendicular to a vertical linethrough the pivot point of the bow grip,plus 134in.(+14,0 in.).3.2.2 brace height,nthe distance in inches or millimetresfrom the shooting string of a bow to the pivot or low point ofthe hand grip,measured perpendicular to the string at theun-drawn condition.3.2.3 compound bow,na type of bow that imposes asecondary system of control of the force-draw characteristic onthe usual limb geometry control system of the conventionalbow.This secondary control system can be composed of cams,levers,cables,or other elements,or a combination thereof.Thedual control system permits great versatility in the design of theforce-draw characteristic and simplifies the inclusion of let-off.In general,it is normal for compound bows to have greaterstored energy than conventional bows for a given level of peakor maximum draw weight.3.2.4 draw,nto move the shooting string of a bow fromthe rest or brace position toward the fully drawn position byapplying force to said string.Such action causes the limbs ofthe bow to bend and store energy.Moving the string from braceheight to the full-draw position corresponds to the draw cycleof a bow.3.2.5 draw force,nthat level of force necessary andcoincidental with drawing a bow to a specific position withinits ATA actual draw length.3.2.6 force-draw curve,nthe curve obtained when thedraw force is plotted versus the ATA actual draw length for agiven bow.3.2.7 full draw,nthe position in a draw cycle of a bowfrom which the string of the bow is released and the forceapplied to the rear of the arrow to commence the launch.Thefull-draw position of individual archers will vary due topersonal physical characteristics and shooting style.Archerybows are specified as to the range of draw length that they willaccommodate to permit archers to select a size that will fitthem.Precise draw length is less of a factor on conventionalbows as compared with compound bows,since it is ideal tomatch the draw length of the archer to the position ofmaximum let-off in the draw cycle of the compound bow.Theposition of maximum let-off for compound bows usually isadjustable within specified limits.3.2.8 holding force,nthe force required to retain thebowstring of a drawn bow at a specificATAactual draw length.3.2.9 let-down curve,nthe curve obtained when the forcenecessary to restrain the bow from returning to brace height isplotted versus the ATA actual draw length.3.2.10 let-down force,nthe force required to retain thebowstring of the drawn bow at a specific ATA actual drawlength during the let-down cycle.This let-down force differsfrom the draw force at the same length by the amount of statichysteresis.3.2.11 let-off,nthat characteristic of an archery bow thatresults in a reduction in the force necessary to increase thedraw length of the bow after the highest level of draw force has1This test method is under the jurisdiction of ASTM Committee F08 on SportsEquipment,Playing Surfaces,and Facilities and is the direct responsibility ofSubcommittee F08.16 on Archery Products.Current edition approved Nov.1,2013.Published January 2014.Originallyapproved in 1998.Last previous edition approved in 2009 as F1880 09.DOI:10.1520/F1880-09R13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 been reached.This is a characteristic generally associated with,but not restricted to,compound type bows.3.2.12 let-off force,nthe minimum force required to retainthe bowstring of the drawn bow subsequent to peak draw forceund