Spent some time apprenticing in a machine shop before becoming an electrician. I was shown to read the chips or shavings to determine pressure and speed when drilling metal.
Straw color or gold is the the most change in color you should see!
Blue is burnt and dulling bits
Useful tricks for apprentices or others that are borrowing my bits on the job are
using clutch on drill,
using a washer over pilot bit to stop the hole saw from biting that first penetration.
Rapid tap is a great lube and cutting fluid for larger diameter or thicker metals.
Carbide is reserved for stainless or other hard materials that High speed steel would be inefficient to use.
I’ve had one Lenox kit for most my career and one greenlee carbide for special metals.
7-8 years on everything but 7/8” and 1 1/8”
My biggest surprise to date was drilling efface (styrofoam with topcoat applied) ground teeth of saw in two revolutions!
Masonry requires diamonds without it heats up bit and takes away temper(hardness)
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