Some of these reviewers don't know what they're doing. This type of bit is going to chatter if you aren't using a drill press (and even then if you try to go too fast), it's not the bit's fault. At the very least you'd need one with a pilot, but then you're looking at a whole set with one for each size hole.I set the press to the lowest speed and it shaved a bunch of deep countersinks in aluminum L-track like it was cheese and left a nice shiny perfectly round hole for some 3/8” countersunk bolts. For drilling you usually go high speed low pressure on aluminum, but in this case that was just very loud and hot (the countersink still came out nice and round but looked rough from the million tiny cuts instead of one steady slice).It's HSS, so I'm only expecting it to last for this one project, and so far so good after a dozen 3/4” holes. Great value for the money. If you're doing this all the time, get a single flute cobalt set for like $200, otherwise you can't complain.
Rating:
[5 of 5 Stars!]