Question 1

Which drill bit material should I specify for stainless steel and hardened alloys?

Accepted Answer

For stainless steel, tool steel and hardened alloys, specify cobalt (HSS-Co, M35/M42 class) drill bits with a 135° split point. Cobalt resists the work-hardening and heat build-up that destroys standard HSS edges. Standard black oxide or bright HSS bits remain the most cost-effective option for mild steel, aluminium, brass and wood.

Question 2

What is the difference between a Type 1 cut off wheel and a Type 27 grinding wheel?

Accepted Answer

A Type 1 (flat) wheel is designed for straight cutting where the wheel edge does the work and the tool is held at roughly 90° to the workpiece. A Type 27 depressed-centre wheel is designed for surface grinding and weld blending at 15°–30°. Using a cutting wheel for grinding, or the reverse, overloads the bond and reduces safe wheel life.

Question 3

How do screw extractors and left-hand drill bits work together?

Accepted Answer

A left-hand drill bit is used first to create a pilot hole in the broken fastener; the reverse rotation often backs the fastener out on its own. If it does not, a tapered, left-hand spiral screw extractor is driven into the pilot hole so that the extraction torque tightens the grip as it turns counter-clockwise, removing the fastener without damaging the surrounding thread.

Question 4

Does Century Drill & Tool supply international distributors and OEM programs?

Accepted Answer

Yes. Century Drill & Tool supports industrial distributors, hardware groups, automotive aftermarket buyers and OEM packaging programs. Full catalogue data, packaging options and technical documentation are available through our Support pages.

Question 5

Are thread restoring files an alternative to re-tapping damaged threads?

Accepted Answer

Thread restoring files clean and reform external threads that are bruised or burred without removing the fastener from service, covering multiple pitches on a single tool. Where thread material is missing or the thread is stripped, a tap, die or dedicated thread restorer set is the correct repair path.

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