Common Counterbore Sizes



 	STANDARD            1/64 OVERSIZE            1/32 OVERSIZE     
	--------            -------------            -------------         
       PILOT   BODY            PILOT   BODY            PILOT   BODY
4-40   .113   .186      4-40   .126   .202      4-40   .144   .216
5-40   .125   .207      5-40   .140   .222      5-40   .1563  .239
6-32   .140   .229      6-32   .156   .246      6-32   .173   .260
8-32   .166   .272      8-32   .182   .287      8-32   .190   .305
10-32  .191   .317      10-32  .209   .331      10-32  .221   .346
1/4    .250   .381      1/4    .265   .396      1/4    .281   .415
5/16   .312   .477      5/16   .328   .490      5/16   .343   .500  
3/8    .375   .596      3/8    .390   .590      3/8    .406   .605  
7/16   .437   .662      7/16   .453   .677      7/16   .468   .692
1/2    .500   .758      1/2    .515   .773      1/2    .531   .790