Bosch CO14B 14 pc. Cobalt M42 Drill Bit Set | M42 alloy with 8% cobalt, jobber-length drill bits for stainless steel, cast iron, titanium, plus aluminum

I never knew the magic of cobalt drill bits until I needed to drill some mounting holes on a steel bench grinder stand. The top of the stand was 3/8 in steel plate and it probably took 20 minutes to get through it with a standard bit. I did some research and ordered these bits. I don't need 50 different sizes because I'm not drilling metal frequently. This Bosch set seemed to be one of the few affordable sets that included the 1/2-in size. Plus... All of the bits above 3/16 I have a three-sided flat grind for better chuck lock up. Used the 1/4 in bit for a pilot and then the half inch bit to drill the remaining three holes. Less than 1 minute per hole, including the pilot, using a bit of cutting oil. It really is like magic. I'll be testing these to drill out a broken bolt in my mower deck next. I will update this review if I experience any durability issues. UPDATE: That broken spindle bolt in my mower deck must be special. Using low speed, a lot of pressure, and cutting oil I made it about a quarter inch into the bolt before dulling the bit. Switched to another bit and made it a bit further before killing that one too. Even with a decent hole drilled in the bolt, my extractors won't grab the hard metal. I'm not going to deduct a star since I didn't expect these bits to be invincible but hope this helps someone determine if these will work for your use case.

Drilling wood is a lot easier on bits than drilling steel or cast iron, but working with hard woods (like bubinga, rock maple, and Brazilian rosewood) dulls them down pretty fast. I'd sharpened the 1/8" bit in my full bit-set so often that it was too short, so I needed another, and thought I'd get Bosch, I'd heard they're quality tools. I bought an extra for the small collection I keep in my drill/driver case, since I use the 1/8" bit more than any of the others. I just received the two Bosch bits last night, went out to finish a shelf project where I had to drill about 40 1/8" holes in rosewood, 1/2" deep. I put this bit in my drill press, and it went into that hardwood like it was butter, no tear-out around the holes, and it's still sharper than I can get on a Drill Dr. I can't say how long it'll stay sharp, but so far I'm impressed

This BOSCH Cobalt M42 3/8" drill bit performs extremely well, especially on hard metals. It made drilling feel almost effortless. Fit: Fits securely in standard drill chucks thanks to the three-flat shank design, with no slipping during use. Size: The 3/8" size is accurate and consistent, making clean and precise holes in various materials. Ease of Use: Very easy to use. It stays stable while drilling and doesn’t require excessive force to cut through tough metal. Compatibility: Works well across a range of materials including stainless steel, cast iron, and aluminum without issue. Case: Packaging is simple and protective enough to keep the bit safe during storage and transport. Appearance: Clean, professional look with a solid cobalt finish that reflects its heavy-duty design. Overall, this drill bit performs like a high-quality tool should. It cut through hard metal almost like melted butter, making it a reliable choice for demanding drilling tasks.

I bought these for an exhaust flange repair where I had to drill-out the old studs. I worked through diameters to get to 3/8. These bits worked well. Bosch has good tools.

Good but sure not the very best like reviews told me

Look no further. Bosch M42 drill bits are the best available. They are very sharp. They last. They will drill stainless steel nicely if you go very slow, use pressure, and do not under any circumstances let the bit spin (that will work harden the material and make it nearly impossible to drill).

These bits drill through steel easily.Well worth the price.

Greta drill bits stay sharp and don't go dull aslong as you take care of them and use a bit of oil. Have multiple sets would buy again.

El funcionamiento de esta broca es muy bueno, se pueden hacer fácilmente perforaciones al metal

Great drill bits.

Quality material.

Buen producto especial para taladrar acero inoxidable

I’m a hobbyist using these drill bits for steel, copper, and general household fixes and I’ve found them to be extremely durable and reliable. I’ve had no issues so far. The edges have held up well and consistently produce clean, precise holes. They’re well worth the investment in my opinion. The seller also provided excellent customer service. They stayed on top of the delivery and even sent a replacement when the package didn’t arrive by the designated time, without me having to reach out at all. Overall, a great product from Bosch and an excellent seller! Definitely would buy more if needed in the future