Homemade diff pin?

[redshift]

What's curious, there is no mention of cobalt on the packaging.... and split points are great if you don't wanna bother with a pilot hole. But they have a thinner flute by nature. I was going to mention, the easiest way to check relative hardness is with a file. A cobalt bit should file away very little, a regular black oxide HSS bit will be hard but a file will win. It's a bit of a misnomer right out the gates, because HSS tool steel is MUCH harder than "HSS" drill bits. Usually tool steel will contain cobalt in higher concentrations, a file will not touch it.