Bosch CO18 18-Piece Cobalt Twist Drill Bit Assortment in Plastic Case

I had a fine set of DeWalt drill bits that see light duty at home. They were adequate for wood and mediocre for plastic (with a tendency to grab and bind). However, I was recently working on an electronics project housed in a steel box with aluminum front and back panels. The DeWalt bits worked ok on the aluminum panels but would scarely scratch the paint on the steel shell. My usual practice is to drill a pilot hole with the smallest drill bit that won't likely break in the process. But, wow, I couldn't get even the smallest drill bit I dared use do more than make a modest dent in the steel shell. I purchased the Bosch drill index specifically for this project. The cobalt-alloy did the trick. I punched the holes through with nominal effort and was delighted that the drill didn't bind after penetrating the metal. These drill bits are fantastic!

I was VERY impressed.

Five stars and two thumbs up!!!!

I'll just tell you from the start. For years I've seen all the talk about Titanium coated, Cobalt coated, and Black Oxide coated drill bits - and for the most part it's just a bunch of BS designed to sell simple high speed steel bits for more cash. A nano coating or a coating the thickness of an oil film is no better than oil - even if it is hard. It wears off in nothing flat when it meets high carbon hardened steel. When dressed/resharpened, these bits are no better than the high speed steel they contain, and will never cut as good again as they did before their coating wore away. M42 alloy cobalt bits return to their original cutting strength when dressed again.

These Bosch cobalt bits are the real deal using M42 containing 8% cobalt for a rating of 66-69 HRC. If you intend to drill harder steels, lesser products will not penetrate them - and will be doing good if they even manage to scratch such steels. These Bosch 8% cobalt drill bits are superior to those of other manufacturers such as Irwin and DeWalt using 5% cobalt and less.

Without going further into metallurgy, you've probably needed to drill something metal at some time - that other drill bits just wouldn't drill into. These Bosch bits will more than likely be able to drill any metal you will encounter. When I need to drill a steel of unknown hardness, I always try a general purpose drill bit first. I swap to my more expensive cobalt bits when I see the cheaper bit is making no headway. So far, my Bosch cobalt bits have drilled through all the harder metals I've tried them on.

Now that you know some of what to use, just don't go trying to drill into the local bank vault.

Comes in a decent hard plastic case with rubber end caps. Maximum operating speed 1500 RPM. Not for use with hammer drills.

Made in China

these are very high quality bits, they are sharp and they stay sharp. I notice they have a very steep angle to them which means that they attack the material rather rapidly.