ASME B18.2.3.2:2005 pdf download Metric Formed Hex Screws
6.6 Thread Length The length of thread on screws shall be controlled by the maximum grip length, L g , and the minimum body length, L s , as set forth in this section.
6.6.1 Grip Gaging Length, L g . The grip gaging length, L g , is the distance, measured parallel to the axis of the screw, from the underhead bearing surface to the face of a noncounterbored or noncountersunk standard GO thread ring gage assembled by hand as far as the thread will permit. For standard diameter-length com- binations of screws that are not threaded full length, the values for L g max. are specified in Table 5. For diameter- length combinations not listed in Table 5, the maximum grip gaging length, as calculated and rounded to one decimal place, shall be equal to the nominal screw length, L, minus the reference nominal thread length, B,as specified in Table 8 (L, max.= L- B)L max.shallbe used as a criterion for inspection. For screws of nom-inal lengths, L, that are equal to or shorter than thelengths specified in Table 8 for screws threaded fulllength,Lg max.=Lu max.as specified in Table 8.
6.6.2 Body Length, Ls Body length, Ls, is the distance, measured parallel to the axis of the screw, fromthe underhead bearing surface to the last scratch ofthread or top of the extrusion angle, whichever is clos-est to the head. For standard diameter-length combina-tions of screws that are not threaded full length, thevalues of Ls min. are specified in Table 5. For diameterlength combinations not listed in Table 5, the minimumbody length, as calculated and rounded to one decimalplace, shall be equal to the maximum grip gaging lengthascomputed,minus the transition thread length as spec-ified in Table 8(L;min. = Lgmax. – Xref.).Lsmin. shallbe used as a criterion for inspection. For screws that arethreaded full length, the distance from the underheadoearing surface to the face of a noncounterbored or non.counter-sunk standard GO thread ring gage assembledby hand as far as the thread will permit shall not exceedthe length,L. as specified in Table 8. For screwsthreaded full length, the last scratch of thread must notbe within themaximum filletlength, Fimax, as speci-fied in Table 3: L min = F max.
6.6.3 Thread Length,B. Thread length,B,a reference dimension, as specified in Table 8, is intended forcalculation purposes only, and is the distance, measuredparallel to the axis of the screw, from the extreme endof the screw to the last complete (full form) thread.
6.6.4 Transition Thread Length，X.The transitionthread length,X, as specified in Table 8, is a referencedimension intended for calculation purposes only, It includes the length of incomplete threads and tolerances