Hymnorq 4.2mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit Set of 10pcs with Straight Shank to Cut Through Stainless Steel Cast Iron and Other Hard Metals

I bought 2 of these and they hold up well which is hard to find for medal bits :)

I want to use these to drill rivet holes for 1/8" pop rivets. The holes are too small. Comparing sizes using a digital caliper, the size in mm is 3.15. The 1/8" drill bit measures 3.14mm when directly comparing back and forth twixt the two numerous times. The rivets read ~3.18mm. I use comparative readings as I do not have a micrometer. I compared the bits against a half dozen imperial bits from different manufacturers and got similar results. Therefore I believe these bits are undersized.

Bits work as expected to drill holes for 1/4"x20 nutserts.

Drill bits seem well made. The case…not so much. Mine came so cracked I barely holds the bits in.

Decent bits. They seem like good quality, but for some inexplicable reason the manufacturer put them in a really brittle and flimsy case. While the bits may last, they will wind up scattered in a drawer.

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.

Problem with search for "Metric Drill Bits" on Amazon is that more than half the items coming up are NOT "Metric". Amazon has the absolute worst search engine on the internet.I ordered these to use when tapping holes for metric fasteners. Specifically I needed 5.0 mm for M6x1. I am hoping the 0.5 mm steps will get me close for other sizes as well. The drill bits seem OK but I only use them for finishing holes that have been pre-drilled with less expensive Imperial (inch) sized bits. As others have stated the case is pain ... Shirley they could do better.

Ok like I said....they work! Yes they are made in China, but that's not always a negative when buying off Amazon. I would give 5 stars but the packaging was my issue. The case is more for display than keeping the drill bits safe. All the small bits had fallen out of there case seat before opening up the case. One of the bits was lodged in a certain way forcing me to use a lot of force to open the case which broke the bit. See broken bit in picture. Glad it wasn't the bit I needed to use right out the box.

Great price for replacement drills and at the price I'll use a few up before starting to sharpen them.

Cuts through stainless ok and I haven't snapped one yet.

Only used onece

je suis content pour cet achat je recommande supers mèches

They have some burrs left over from however they are sharpened.