Обший каталог Yamawa 2016 - 2017 - страница 852

Center Drills

Center Drills are the tool for making center hole. Center Drills are also used for positioning before drilling, and for chamfering of the hole. ■

■Names of each part Shank portion Countersink portion

Drill diam. Drill portion

Drill length Overall length

■Shape of center hole and center

Type A (60°) Center hole & 60°center Type B (60°) Center hole & 60°center Type A (90°) Center hole & 90°center Type R Center hole & 60°center

■Advantage of Type B Center holes

Note : Advantage of Type B center holes : B type center drill protect the 60° conical bearing surface from scar or distortion resulting from a blow, roughness of workpiece surface or burrs around the hole.

■Advantage of Type R Center holes

Angle of center hole is higher than Angle of center hole is lower than Center hole and center are misaligned. that of center. that of center.

A type

R type

Note : R type center hole stably holds the center. It also some of advantage of B type center hole.