Slow down drilling. More pressure is better.
Use a water soluble oil. Cutting oil doesn’t cool like the water does.
Heat is your enemy.
Cobalt drills are maybe 3 points harder on RC than regular HSS. Worth it.
The titanium nitrate coating only helps if you have a good steel under it.
You can coat carbon steel.
135 with a split point. 135 deg is less tool interface.
Split point takes less tool pressure.
Run a fine stone across the the cutting edge. Crates works best. Sandpaper is fine. So it’s smooth when you run your finger along it.
That very sharp edge breaks down quicker. And then you are dull.
The stoned edge is much tougher.
I’ll drill thru 4’ of parts of 410 or 316 SS without having to sharpen the drill. 2” drill. Regular HSS not cobalt.
I’m too lazy not to do it right. Some guys will go and hand sharpen 5-7 times for the same job.
Any other questions. Just ask.
And slowdown and keep the pressure up.
Last edited by 257_X_50; 03/27/20.
