Niagara CutterN46420 Carbide Square Nose End Mill, Metric, AlTiN Finish, Roughing and Finishing Cut, 30 Degree Helix, 4 Flutes, 39mm Overall Length, 3mm Cutting Diameter, 3.000mm Shank Diameter

I've been using this for a while on a small mill. Much better than HSS end mills- cleaner cuts, less chatter. Well worth the extra cost.

Okay, I have been attempting to drill a new hole for a thumb stud in my SOG knife. They must have used some really high quality steel (as true knife steel is supposed to be), because it absolutely disintegrated a regular drill bit in seconds, slowly disintegrated the tip of my diamond bit (yes, diamond is harder than steel, but it's only as durable as the paste used, although the diamond bit made a dent in the blade), and even defeated a special M42 HSS drill bit set I bought especially for the task. The M42 we probably about as hard as the blade steel, holding up for hours of slow drilling, but not making headway and just getting dull. ALL THAT -- and this Niagra Cutter carbide bit cut through in MERE SECONDS, and cleanly too. Quite impressed. This carbide bit is definitely the way to go if working with hard steel (or anything else your drilling as long as it's in a drill press or CNC machine. I didn't have any problems with it being too brittle. It was in one piece when I got it, didn't break when I handled it, and didn't cup or break when I used it. I was careful, but not excessively so.

I needed a 3mm flat endmill to plunge cut in aluminum. I was nervous about chip plugging but the coating did great. I bought two anticipating destroying one but I got all parts done with just one cutter.

Cut a 4" long keyway, through a weld heat affected zone , 2 different pieces of mystery steel welded together...Using a mill drill..Sputtering coolant...no power feed..I was afraid of it being fragile since it is carbide but the corners did not even chip...

A great mill for hardened steel. I needed to plunge with it and I did not do any side cutting, but I expect it would do that just fine.

Not too impressed. First use broke two of the flutes off drilling out a broken cheap bit even using cutting fluid and going slow. To its credit i did manage to suceed in the task but now its garbage