8 . S . 5 7: l 9 5 l ' TABLE 2. ROUND HEAD SCREWS 4..' Nominallength Fig. 3. Roud hcad ccrll u l t t l t t Dirnetcr of rbralc end nrix diroctcr ol tbnced D B.A. No. Dirmctcr ol hcrd Ilcpth ol boed Dca|t J B Dt!. IDII. Dto. DOD. -:-' ln. ln. in. I in. tn. 2 0.r23 0.015I 0.J19 0.052 o.044 0.07t 4 o.ror o.095 0.010| o.?sz 0'040 0.034 0.056 | iJ-6i0.r4z lo.zszto.z4z I Preferred| 6 I 2.8 | o.Ir0 | o.ts+ : 0.184| 0.0?8 0.0/3 0.010| 0.194 0.033 o.wl 0'043 0.059 0.010| 0.15? 0.030 o-v24 0.0J5 io.r+z I s lz.zlo.wlo.rsz lo.oar ln. 0.041 0-0tr/| 0.112 o.u4 I o.uz o.ro7 I to |r.zI o.ooz | o.o+s t - l - t - t ofi6-o | 0.236 0.41J: 0.405| 0.167, 0.159 Second I I 15.3I 0.209i 0'366i o.ssoI o-r+si o . r 4 l choice o.rrsi o.roz I ti4.r 0.16l'o.zaslo.ztsl 0.126 o.nLI o.zrrI o.* I s is.z-r-l-ll--l- 0.083 o.019 o.gz5 0-413 0.064 0.056 o-wz 0.J66 0.0s8 0.050 o-081 0.28J 0.04? 0'039 0.062 Unr 0.040 0.0J4 0.048 i o.u3i 0.163 | ? i 2-s,0.0s8 | 0.06eo-oal 0-0lo i e I r.e I o.07si o.r28I o.rzJI o.osz0.or8 0.007 Not Iu 0.r73 0.03J o-u27o.ql8 o.128 0.030 o-az4o.an 0-04r 0-00s 0.tI0 0.a240.019 0.025 lr.s I o.osg I o.uo|o.ros i o-oqs O.VzL normailvI 12 ir.3 i o.osr| 0.095| 0.090| 0.038 0-035 0-005 0.095 0.020 0.015 l I srocked I 13 lr-2 i O.sl?; 0.08r o.oz0 0.032 0.929 0.005 o.08l o.Oao0.0I5 0.0I8 14 l1'0 | 0.0J9i 0.064: O.059: 0.926 o.az' 0.003 0-064 o.ol5 o.orr 0.014 j o.oaoo-43 0.003 0.0& 0-ot5 O.OII o-0r4 i o.osg rs lo'gI o.oss I o-ooo 16lo.?91 ; o.os+ o.osri o.osa i o.oas0.020 0'001 0.058 0.013 0.009 0-015 t It is recommendedthat % in. B.S.F. screwsto B.S. 450, ' Bright countersunk, round and cheese head screws(B.S.W. and B.S.F.),'be used in preferenceto O.B.A. NOTE t. If the slot is produced by plunge milling, dimensionJ is measuredfrorn the uppcr surl'acc of thc head to the point at which thc slot breaks out on the surface of the head. NOTE 2. Shape of head. The shape of the head shalt closely approximate to a half-ellipse Radius G (struck off the undersideof the head) must pass through diameter A and touch radius F.