Drilling hardened A2

[joefrombc]

Good evening. I have a large plane blade I'm turning into a flushing chisel. It is made from A2, 3/16" thick, hardened to around 60RC (guess). To mount the handle boss, I need to drill a pair of 1/4" holes through. I have solid carbide twist bits for pilot and finishing holes, but I'm pretty sure I'll ruin all my punches trying to mark it. Would a solid carbide spot drill be a good alternative?

I have a decent drill press and okay fixturing. Some run-out, but no triangular holes at least.

Thanks.

 

[Former Member]

Yes.

 

[joefrombc]

And just like that, I bought a spot drill.

Thanks Degen.

 

[Dabbler]

I was going to also suggest to use a 1/4" carbide end mill to create a starting place, but a carbide spot drill would work a lot better!

 

[Chip Maker]

If you had a mill, I would use a carbide center drill. Cement drills properly sharpened work well on hardened tool steel as well.

 

[Dabbler]

I strongly prefer spot drills to centre drills for non-lathe work. No downside to spot drills, and no upside to centre drills in the mill. Lots of 'old school' guys use centre drills for spotting, however.

 

[trevj]

I strongly prefer spot drills to centre drills for non-lathe work. No downside to spot drills, and no upside to centre drills in the mill. Lots of 'old school' guys use centre drills for spotting, however.

Likewise.

A carbide spotting drill, if used carefully, is liable to outlive the user, so the cost is pretty easy to absorb. Small diameter Carbide is pretty inexpensive too, though a bit fragile in a not very rigid drill press!

I like carbide for when it is needed, the rest of the time, it's better to spend your money on what 'else' that may serve the needs!