How can I drill through 1/4" hardened ,galvanized steel?

Question

I have tried some dewalt hss bits but they only blunt,The hole needs to be 6mm diameter,thanks

Answer 1

Make sure you OIL the cutting. Few things wear a drill bit faster than trying to "dry drill" hard metal, especially at high speeds, but a lot of beginners do this. Use a powerful drill, pressure, steady speed (no, you don't want HIGH rpm, drilling is a CUTTING action, not a grinding one), and adequate lubrication. If long chips spiral out, you're doing good. If you're getting powder, you're ruining your bit, and you might not even finish drilling through.

For extra hard steel (I can't imagine GALVANIZED super-hard metal), use tungsten carbide bits. You might be able to get them at the hardware store, but you might have to ask where to find them. You'll have better luck at shops specializing machine shop supplies.

Answer 2

Try a cobalt steel bit in a drill press. Lubricate with 3-in-1 oil for a cleaner, easier cut. I drilled a 1/4" hole through a vanadium tool steel wrench with a cobalt bit, so I know it can be done.

Answer 3

The biggest mistake most people make when drilling in stainless is to spin the drill as fast as they can. Heat builds up and work hardens the steel, after that you are screwed. The sheet metal guys here do stainless counters for commercial kitchens all the time. They taught me to pulse the drill. Trigger the drill in one second on, one second off pulses and use plenty of oil for lube. They use bits and hole saws to cut this stuff all the time and they manage to make them last this way.

Answer 4

Besides good bits , you need a poweful drill with hight rpm; try using titanium drill bits; make sure you are using drill bits for metal and not for masonery.
Make sure to wear gogles to protect your eyes, a few guys have end up with a broken drill bit into the eyes, also wear gloves; Drilling metal sometime takes to brake a few bits so be carfull.

Answer 5

If none of these drills do it, try softening the steel at the point where you are drilling with your welding torch and let it cool slowly

Answer 6

you need a diamand tip drill bit ,costly, a cooling liquid and a slow speed drill fixed to a bench .

Answer 7

use a tungsten drill bit, like a hot knife through butter