如埋头螺丝(Allen Screw)上之方孔或六角孔,均为不穿者。在普通工场中小量制造,颇感棘手。下图所示制造方法,颇为容易,可以为一般工场所采用。兹以钻0.281″方孔为例:钻力孔时必用三角钻,此三角钻之端面,如图所示。应用时,必需装于活动刀架上,可于进刀时有旁向走动,不致折断钻头。工作物装于夹具上,其上为一方导孔,其尺寸亦为0.281″方。此法之缺 Such as square screws (Allen Screw) on the square hole or hexagonal hole, are not wearing. Made in a small number of ordinary workshops, quite tricky. The manufacturing method shown in the following figure is quite easy and can be used for normal work places. Here is a drill 0.281 “square hole for example: drill hole must be used when the triangular drill, the triangular drill face, as shown in the figure, the application must be installed on the active tool holder, Will not break the drill bit work on the fixture, which is a guide hole on the side, its size is also 0.281 ”square. The lack of this method