ASTM_F_1832_-_07_2011.pdf

Designation:F183207(Reapproved 2011)An American National StandardStandard Test Method forDetermining the Force-Draw and Let-Down Curves forArchery Bows1This standard is issued under the fixed designation F1832;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 force-draw and let-down curves for archerybows.1.2 The values stated in inch-pound units are to be regardedas the standard.The SI units given in parentheses are forinformation only.1.3 This standard does not purport all of the safetyconcerns,if any,associated with its use.It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices,and determine the applicability of regulatorylimitations prior to use.2.Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 ATA(archery trade association)draw length,nperpendicular distance from the point where the shootingstring of the bow contacts bottom of the nock slot of the arrow,to a vertical line through the pivot or low point of the hand grip(draw length pivot point),plus a standard dimension of 134in.(44.5 mm).2.1.2 brace height,ndimension in inches(millimetres),from the grip pivot point(low point)of the grip to the nearestside of the bowstring,measured perpendicular to thebowstring,with the bow strung and in the undrawn condition.2.1.3 compound bow,ntype of bow that imposes a sec-ondary system of control of the force-draw characteristic on theusual limb geometry control system of the conventional bow.2.1.3.1 DiscussionThis secondary control system can becomposed of cam,levers,cables,or other elements,andcombinations thereof.The dual control system permits greatversatility in the design of the force-draw characteristic,andsimplifies the inclusion of let-off.In general,it is normal forcompound bows to have greater stored energy than conven-tional bows for a given level of peak or maximum draw weight.2.1.4 draw,vto move the shooting string of a bow fromthe rest or braced position toward the full drawn position byapplying force to said string.2.1.4.1 DiscussionSuch action causes the limbs of thebow to bend and store energy.Moving the string from braceheight to the full draw position corresponds to the draw strokeof a bow.2.1.5 draw cycle,ncombination of the draw-stroke andthe let-down stroke,resulting in a full cycle from brace heightto full draw and return to brace height.2.1.6 draw-stroke,ndistance in inches(millimeters)frombrace height to full draw.2.1.7 force-draw curve,ncurve that is plotted using theforce readings,taken at incremental values of draw lengthwhen drawing the bow,as the ordinate and the correspondingdraw length as abscissa.2.1.8 full draw,nposition assumed by the bowstring whenthe bow is drawn to a draw length corresponding to that fromwhich it will be released for the shot.2.1.8.1 DiscussionFor most standard test purposes fulldraw is specified as 30 in.(762 mm)ATA draw length forcompound bows,and 28 in.(711.2 mm)ATA draw length fornon-compound bows,but it can take any assigned value.2.1.9 let-down curve,ncurve that is plotted using the forcereadings,taken at incremental values of draw length whenrelaxing the bow,as the ordinate and the corresponding drawlength as abscissa.2.1.10 let-off,ndifference between the peak or maximumdraw force reached during the draw stroke of a bow,and thelowest level of draw force reached subsequent to that peak.2.1.10.1 DiscussionQuantitatively,it is most frequentlyexpressed as a percentage of the peak force and is then referredto as percent of let-off.2.1.11 non-compound bow,nbow constructed in the tra-ditional manner,having two flexing limbs extending outwardlyin opposite directions from a handle.2.1.11.1 DiscussionA single shooting string of a lengthshorter than the bow,connects the extreme ends of the limbscausing them to assume a pre-stressed flexed condition.Draw-ing the bow causes additional bending and stressing of thelimbs,storing the energy necessary to propel the arrow.Control1This test method is under the jurisdiction of ASTM Committee F08 onSportsEquipment and Facilities and is the direct responsibility of Subcommittee F08.16 onArchery Products.Current edition approved June 1,2011.Published July 2011.Originally approvedin 1997.Last previous edition approved in 2007 as F1832 07.DOI:10.1520/F1832-07R11.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 of the force-draw characteristic of the bow is exercised entirelyby the static and dynamic geometry of the flexing limbs and thebowstring.2.1.12 peak draw force,nmaximum force reached whendrawing a bow.2.1.12.1 DiscussionFor conventional bows,the peak drawforce is usually reached a