Blue Granite - now that's a name that instills confidence. Bosch was going for the manly persona when it came up with that one (but what else should we expect from a German company?). Carbide hammer drill bits are for made for one thing: fast impact drilling in concrete, stone, or masonry. Bosch uses a high temperature brazing process to keep the carbide cutting edge from breaking out during deep drilling when bits tend to get very hot. The bits come in various lengths up to 12" (usable lengths up to 10").

Tech Note: Brazing
Brazing joins two or more close-fitting parts by heating a filler metal or alloy to a melting temperature above 800 degrees F (427 degrees C). At its liquid temperature, the molten filler metal and flux bonds with a thin layer of the base metal, and cools to form a strong, sealed joint.

In our use, we pitted a 3/16" Bosch Blue Granite bit with our DeWalt hammer drill and let 'er rip into some concrete block. The goal was to secure a piece of pressure treated lumber to the wall courtesy of four Tapcon anchors. What we found was that the Bosch bit was easily driven into the concrete by the hammer drill and we encountered no real difficulties. Since the particular job we chose was a repair for a plumbing leak we did encounter some wetness, which stuck to the bit like paste. Normally, the dust would be easily extracted by pulling out the bit and plunging it back into the hole. In our case we had to remove the paste manually using our fingers. Not a show-stopper and we certainly don't think any other bit would have done better.

What we did find was that the carbide tip of the Blue Granite bit stayed sharp and well-honed, even after drilling through what amounted to 6 inches worth of concrete block. We also found that the bit seemed to really tolerate high speed drilling (with the hammer drill function engaged) - something you aren't going to have much luck with when using a non-carbide tipped blade.

Overall, the Blue Granite line from Bosch is a good bit for masonry drilling and we highly recommend it. There are other choices, but these bits are actually a great value and not priced at a premium. You can also find them nearly everywhere and they come in convenient kits so you always have the size you need.

About Bosch
Power tools from Bosch are among the most popular tools worldwide. No wonder: Bosch stands for quality, excellent accessories and outstanding service. With Bosch, you not only have more options, you also work much more precisely, flexibly, safely and far more productively. Our tools impress by their quality, first class handling and state-of-the-art technology. Whatever you want to build, you can do it with Bosch.