Working with hard metals requires the best cobalt drill bits. We tested top picks to see which bits could bore through the toughest metals. Check out our reviews and discover which one came out on top ...

And heat dulls bits quickly. In general, it’s a good idea to drill through metal using as slow a speed as possible using a drill bit for metal. Hard metals like steel and larger drill bits ...

It turns out that a hot solution of alum (ammonium aluminum sulfate), which is available in the spice rack of your local supermarket, will dissolve the steel ... for larger drill bits, but the ...

A smith may dunk a freshly forged sword into a bucket of oil or water to make the metal harder, or a craftsman with a drill bit ... than untreated steel, therefore the bits last much longer.