13-Piece Cobalt Drill Bit Set with Index Case – M35 Grade (5% Cobalt) Steel, 1.5mm to 6.5mm, Dual Twist Flute, 135° Split Point, Ideal for Hard Metals Like Stainless Steel and Cast Iron

Excellent quality bits for the price. Super sharp and dimensionally accurate cut through mild and semi hard stainless steel like butter. Slow speed and well lubed is the way to go.

At the time I purchased these, I only intended to use them for light duty (drilling into polymer). However, as fate would have it, I had to use them to drill into hardened steel, and much to my surprise, they performed admirably. It was a pleasant surprise (I was expecting "Chinese junk") and I'm very happy with this purchase; especially considering that it's a METRIC set, which is difficult to find (in the USA). I wish the set had a 1mm bit, but oh well. It's just a preference, not anything against the quality of the bits in this set. ============= Update 1/16/18 ============= My rating has changed from 5 stars down to 3. I needed to drill into metal again--actually I wasn't even drilling new holes, but just "chasing" already existing holes to expand them--and neither the 4.5mm or 4.8mm bits would do anything. They just spun around getting hot, without cutting anything. I even tried the 5mm bit, even though that was too big for my purposes, and it also did nothing but spin. Thus, I've used four of the bits (4, 4.5, 4.8, and 5mm), and only one of them did anything. The one that actually worked did its job well; the others are a HUGE disappointment. ============= Update 1/25/18 ============= Kudos to Migiwata customer service (thank you, Bella!). After hearing about my not-so-pleasant experience with these bits, they sent me a second set. Apparently their original supplier had run dry, and they had to use a second, temporary supplier while the original caught up with demand. The first set that I received was from the temporary supplier. The new set is from the original supplier, and the bits seem to be in order in this new set. So how do you tell the difference? By the case (see photos). The set with the blue dot on the case--which is a plastic retainer to keep the case closed--is from the original supplier. Now if you happen to get a set without the blue dot, don't panic. Just because I got a subpar set that slipped through the manufacturer's quality control process doesn't mean that you did, too. Try the bits out first. WORST case is that Migiwata customer service takes care of you like they did me; best case is you don't even have a problem. As for me and my review of this product, I'm a happy camper again and am bumping my rating back up to 5 stars. The bits are great (make sure to use a good cutting lubricant/coolant) and Migiwata customer service is stellar.

Mala calidad de las brocas, se rompen facilmente.

I like this little set. After trying a couple others that were either too dull or too soft or both (and basically only good for 1 hole in steel), this one has taken quite an amount of (ab- and mis-) use and still doing strong. Drills through cast iron and mild still like a champ; can handle toolpost steel and stainless steel in both drill press and lathe. Will be ordering another set just to have a spare (and because the thinner ones did snap but that's my fault).

Excelente produto