BOSCH CO2135B 1/8 in. x 2-3/4 in. Cobalt M42 Drill Bit (Pack of 2)

Anything bosch makes is good, but i feel like they have it down pat when it comes to stuff like twist drills and bits. The M42 cobalt keeps the drill from getting too hot and also acts as a "lubricant", both contributing to keeping a sharp cutting edge, giving it quality and ease of use.These factors reduce the need for either resharpening, or worst, replacing the drill. The cost of cobalt bits are what scares people away, but if you're gonna be using it more than 2 or 3 times, its worth the upgrade from black oxide or a coated bit, thus giving it great value for money.The "M42" is a reference for the amount of cobalt used in the "material makeup" of the bit, with 8% cobalt being used in M42, and 5% cobalt in M35. Both are great options, but i recommend getting an M42 version when possible.The use of cobalt doesnt change the size or shape of the drill, although some will have different flute counts and designs, some tips have a "no pilot hole" start and some will have different degrees of an angle at the head to help with different types of material. Overall, storage capacity will not change unless you opt for different lengths, such as mechanics and aviation length.To sum this up, this is a great drill that should last a long time if used correctly. Bosch is very prevalent in my drill cabinet, so dont be afraid to spend a little extra and get the good one!

Got this kit for blacksmith shop.I have used it in a hand drill and a drill press.I drilled multiple holes in succession in 1/4 , 3/8, and 1/2 inch soft steel.using the 1/4 and 3/8 inch bits.Worked well. The bit are durable. None have broken and they remain sharp through multiple jobs.

I must say, these Bosch drill bits are an absolute must-have in your toolbox. Having tried various brands over the years, I can confidently say that while some of my other drill bits cost a little less, they simply do not perform as well. The Bosch drill bits stand out because they drill through materials much faster and with significantly less effort.The precision engineering of these bits ensures clean and accurate holes every time, which is essential for any DIY project or professional job. I’ve noticed a remarkable difference in efficiency; tasks that used to be time-consuming are now completed in a fraction of the time. If you're looking for reliability and performance, investing in Bosch drill bits is definitely worth it. They make every drilling job easier and more enjoyable! Highly recommended!

Great drill bits, but the case is not good. The latch on my case broke on first opening.

I bought this set of bits to drill 1/2" holes through 1/4" SS for a project. They are worth their weight in gold. Very impressed with cutting efficiency and longevity of the bits. I was able to knock out in one evening what I anticipated would take several days.

I often drill 5/16" holes in some parts I cut on my CNC Plasma cutter. Each part has 8 holes that I cut small and drill to final size. Plasma cut holes have a hardened edge and wrecks inferior drill bits like the one on the right of my photo that I have sharpened so much it is half sized now. This cobalt one went through about 150 of those holes like butter before I had to sharpen it! I was impressed. It is still working great as long as it has a properly sharpened tip.

I usually use carbide drill bits for hardened metal. Thought I would try these. So far they cut great, but don’t force them, let the drill cut with light pressure.

After burning out my old bits trying to drill out a half dozen broken off bolt heads on a rusty car frame, I put this set right to work the day they arrived, using progressively larger sizes and they performed beautifully. It's not a complete set by any means, as I had to purchase a bit separately to pre-drill the holes for a metric tap. Overall I'm very happy to have picked up this set for basic heavy-duty drilling on DIY repairs. For my purposes it's a good combination of quality at a decent price.

These worked great to drill the hard metal A pillar in my LR3 that other people reported having trouble drilling. Didn't even need the second one.

High quantity drill bit to supplement my already complte set. It is longer than the ones in a set. Great when you need to drill a deeper hole.

Excellent bits. They cut steel very well and as long as you pay attention not to overheat them they'll stay sharp a long time.

Actually DOES go through steel

Good bits for the price.