Review of Mibro 492470 17-Piece Cobalt Metal Master Set, 1/6-Inch to 3/8-Inches

I've owned lots of different drill bit sets, including poor quality cheap ones, HSS, titanium-coated, and cobalt. It's easy to get confused with so many things on offer. These Mibros are my favorite, and top other cobalt bits, including the Bosch set (I have them also) for two reasons. Let me explain why.

First, a discussion of drill bits in general. Bits simply labeled HSS (high speed steel) are great for wood and soft metals, but eventually get dull, even in wood if you use them a lot. Titanium coated--well, supposedly hard, but it depends on the quality of the coating. Cheap ones don't last at all, and if you are going for the expensive ones, you might as well just get cobalt, which is even harder. But with cobalt, there's a catch.

Most cobalt bits are made from M-42 cobalt. M-42 describes the specific alloy; M-42 contains 8% cobalt. This is the hardest of the cobalt bit alloys, but it has a disadvantage: it is also the most brittle. Small bits in particular are prone to breakage. This was the case with my Bosch set. After a year or so, several of my smaller bits had broken. It didn't take me long to realize that a very hard bit is a very useless bit when broken!

So I got the Mibros, which are made from M-35 cobalt. M-35 is still quite hard. It contains 5% cobalt--certainly quite enough for anything I drill (which has included drilling out some hardened steel set screws, hardened steel construction components, and stainless). But it is considerably less brittle than M-42 steel. Result--no bit breakages to date.

Another distinct advantage--the 3 flats on bits that are 3/16" or larger. These flats allow the bit to be thoroughly gripped. My Bosch cobalts frequently slipped, resulting in small burrs along the bit shaft that had to be filed down before I could get them back in the bit case--an unneeded annoyance. As for drill quality--extremely smooth.

Conclusion: the Bosches may look like a better buy, but the Mibros in my opinion are worth the extra money. They will last longer because they are less brittle, and you avoid slippage due to the 3 flats. The Canadian manufacturer's thoughtful design and choice of alloy leads to a superior bit set.

Click Here to see more reviews about: Mibro 492470 17-Piece Cobalt Metal Master Set, 1/6-Inch to 3/8-Inches



Buy NowGet 10% OFF