Paul, quenching will only harden it if it gets hot enough to glow. If you stop at the point where the oxide colors are blue and quench, the steel is nicely machinable. Varies a bit depending on alloy, you won't soften air hardening steels this way.
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Paul, quenching will only harden it if it gets hot enough to glow. If you stop at the point where the oxide colors are blue and quench, the steel is nicely machinable. Varies a bit depending on alloy, you won't soften air hardening steels this way.
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Steven, thanks for explaining.Originally Posted by Steven O Smith
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Brass = zero rake. The tiniest little bit of 'blunting' the edge parallel to the axis of the drill will do it. Not really a huge deal, until you're breaking through the off side. IOW, blind holes, don't bother.
Muscle memory is what I use. And eyeball the 'chisel' at the center for ... 'center'.
It's just a drill. Yeah, for wood it's more likely for a finished size than for metal work ... clearance holes for screws aside. Split point stub 'screw machine' drills outnumber 'jobbers' in my cabinet by at least 3x. Something important gets a new one ... pretty hard to regrind them properly with the split. I've free-handed a few large ones, just to reduce the thrust required. It's kinda hard on the quill feed of a mill.
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