Blue Granite – now that’s a name that instills confidence. Bosch was going for the manly persona when it came up with that one. Of course, what else should we expect from a German company? Carbide hammer drill bits are made for one thing: fast impact drilling in concrete, stone, or masonry. The Bosch Blue Granite drill bits use 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″).
Testing the Bosch Blue Granite Bits
In our use of the Bosch Blue Granite drill bits, we fit a 3/16″ Blue Granite bit into our DeWalt DCD985 hammer drill. We then 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. The hammer drill easily drove the Bosch bit into the concrete. Since this job dealt with a plumbing leak repair, we did encounter some wetness. That 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.
Tech Note: 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.
Using the Bosch HCGB700T Bit Kit Over Time
We found that the carbide tip of the Blue Granite bit stayed sharp and well-honed. That stayed true 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. That’s something you won’t have much luck with when using a non-carbide tipped blade.
Overall, the Bosch Blue Granite drill bits 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.