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Module 6: Materials & Hardware22 Aug 2026

why 120 degree for stainless not 118

Exam question

When drilling stainless steel, use a

  • A.drill ground to 120 °, slow cutting speedCorrect
  • B.drill ground to 90 °, fast cutting speed.
  • C.drill ground to 90 °, slow cutting speed.
Explanation

Stainless steel is drilled with a drill ground to about 120° at a slow cutting speed.

Budi S.

asked · 22 Aug 2026

Author
always use 118 degree drill for normal jobs. why stainless need 120 and slow speed, not fast like i thought for harder metal. is it because it work hardens if you go too fast? anyone know the actual reason not just the answer

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