Drilling Through Hardened Steel

[1972K20]

Ok, I've got a metal table that I want to mount a vise to. This table is 1/4" of hardened steel. So, I go to Tractor Supply and by two drill bits for metal. One smaller bit as a pilot and then the larger size 3/8 bit. (this is the bit http://www.tractorsupply.com/en/stor...-8-in-x-525-in )

So, I'm using a 18v DeWalt and using 3in1 oil and I SLOWLY start drilling. Nothing happens. Nothing at all! It just scratched the surface of the table. I did this for a while and then quit after realizing it wasn't working.

So, my question is, how do you go about drilling into such hard steel?

[evan396]

You can try a carbide drill, a little pricey though and brittle. I have also used a mason bit, they have carbide tips on them. When all else fails you can try heating the spot where you are going to drill, this should take the hardness out of the metal seeing that it is probably only surfaced hardened. Let us know how you make out.

[truckster]

Did you center-punch the holes? It not only centers the bit, it gives it a small edge to bite on.

[evan396]

Try heating the spot first then center punch it, otherwise the center punch won't do anything to the hardened steel. Find a spot on the opposite side of your work bench to try it.

[1972K20]

No, I didn't use a center punch. I can try that, but I don't have a way to heat it.

[PGSigns]

Never seen a table build g
from hardened steel. Have seen some built from some pretty good stuff. First test is to center punch it and see if it leaves a mark. It should. Another test is to run a file across the edge and see how it cuts. If a file will cut it it can be drilled. You are going to need good quality bits and a center drill if you can find one. A good cobalt steel bit will cut most any steel you can weld. It will have a 143 degree split point to help it cut the harder material. Home depot has some of them. Straight engine oil will do better than 3&1, Tap Magic will do even better. I have seen some of the offshore bits that won't drill rotted pine.
Jimmy

[cdowns]

Slo drill speeds help the harder the steel the slower you go

[jetmech85]

Use a carbide or carbide tipped pilot drill. They can drill a file. Start with about a 5/32. After you get the pilot hole you might try a 3/8 cobalt drill to save money. A metal cutting carbide drill is brittle like glass so be careful exiting the hole. Try to position your body so you can apply most of your weight when drilling but let up before you break through. Good luck.

[LPoole]

Try to find some tungsten drill bits. Pretty hard without being near as brittle as carbide bits. A lot cheaper too. A pilot hole is a must. And use cutting fluid, not wd40 or 3in1 oil. Slow s-l-o-w drill speeds. Buy a few bits of each size hole you are gonna drill. Once that hard metal dulls the bit and you stop seeing shavings its time for a new, sharp bit (you can also sharpen the used bits with a bench grinder or belt sander). Best of luck to ya.

[BR3W CITY]

Plasma cutter, the hog the hole with diamond die grinder bits. The first part will take 20 seconds, the second part will take....well...a while.

[JJH Jimmy]

Mag drill with carbide hougen bit.