Standard of Center Hole and Center Hole Drill

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Center Drills, Centering Tools Standard (Screw Threads, Center Holes)Tool Selection

I was recently asked to machine 2 center holes "φ1.25 × 60 °" and "φ3.15 × 60 °" . Do I need a special center drill for machining these two center holes? Are "1.2 x 60 °" or "3 x 60 °" the standard center holes?

The update JIS standard for center holes has been standardized with the ISO standard and changed into "A type 1.25 x 60°" and "A type 3.15 x 60°" etc. The "1.2 x 60 °" and "3 x 60 °" became the old JIS standard.
However, the current situation in Japan, it seems that the old JIS center hole standard is still being used frequently. YAMAWA also has stock of the CESA (JIS A type 60 °) center drills that complies with the current JIS standard, so it is still available to purchase.

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