M35 Cobalt Drill Bit Set 20PCS(1/16"-1/2") High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal with Index Storage Case

Probably the best affordable drill buts on the internet ive used them to drill out snapped off taps and studs mainly in turbos off of 3.5 ecos.

Drill bits works ok

Bought 2 for the shop. Used 1 and some bits were dull and rest cut ok. One didn't even start to drill much and it snapped. Have to use it more to see how they work About half the set wouldn't drill cut at all.

Haven't had the chance to use yet but they seem to be of great quality

I got these to drill holes through thin stainless steel. They worked really well. They have two straight sides on the bottom so they don't spin in my drill. Very tough, went right through without a problem. They come out fairly easy but the car holds them good too. The price was right. I had to cut through the metal slowly but surely.

Cobalt is the best to be able to drive through metal that I have ever used

Nice set of common size cobalt drill bits. Cuts like cobalt should. Using a drill press makes these easy to use. Also used in portable DeWalt battery drill. Would buy again.

I did not use these Brill Bits. There is no mention of "Cobalt" on the packaging, just "M35", even though the description *at time of my review) is described as "M35 Cobalt Drill Bit Set 20PCS(1/16"-1/2") High Speed Steel". M35 Drill Bits are defined as "high-speed steel (HSS) bits contain 5% cobalt, making it significantly harder, more heat-resistant, and more durable than standard HSS bits". I purchased other "Cobalt" Bits, which look different in color and work well. These look exactly the same as my current Titanium Bits, defined as "High-Speed Steel (HSS) bits coated with Titanium Nitride (TiN)". As they are coated, it has been my experience with them that they can become blunt very quickly depending on what you are drilling into. I like the idea of Cobalt M35 Bits as they can potentially be resharpened because the alloy is used for the whole bit, not just a coating.

Case is lighter duty than I'd like but the bits themselves cut like crazy. Good first set for the home machinist. Have used multiple times on hard steel and the seem to hold an edge. Probably wouldn't use them with a hand drill as they may be quite brittle, but fine for the drill press.

The item description states that these bits are Rockwell 67. The 3/16" bit couldn't drill through a test wood spade bit 3/16" thick with a Rockwell 55 rating! A pre-existing hole of 1/16" from a previous attempt with a tungsten carbide bit did not help the bit drill through. The bit barely scratched the surface. I didn't push the test any further with stainless steel. I'm glad I tried these before ordering the larger sets in both SAE/metric. These bits will not go through tempered steel at 45 or more Rockwell and certainly wouldn't drill anything harder like stainless steel! How did this get on the market?

Cut through mild/hardened steel, get dull at hardened tool steel.