1/16" (23pcs) Cobalt Drill Bit Set, M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Storage Case

I cleared a stripped screw head using one of these bits and it took me less than 20 seconds. I had previously tried using several different extractors and none worked. One of these bits was literally the only way I could remove the screw. For note taking purposes, the screw belonged to a door knob and was also warped. I am happy with the quality of all of the drill bits. Mine came slightly lubricated with some kind of machine oil. The affordability of these cobalt drill bits is excellent and their performance is even better. The speed that I was able to remove the stripped screw with was amazing. I literally drilled into it and the lingering stuck knob literally fell off. If all else fails and you're trying to remove a stripped or warped screw, try using these bits to help you out.

impressions following first, succesful, use. - bits are sharp and straight. - bits are capable of cutting deep into snapped stainless bolts without observable wear. tips: - the metal set case is tightly clipped together when closed and hard to open. instead of force, i've used a small pry tool. - drilling metal: i've started small, slow, then gradually ramped up speed and size - careful throughout. - reminder to drill "backwards" with left-hand bits. in the photo: the two bits that i've used to extract the snapped bolt, also shown.

The drill set is as shown . The metal housing is damaged from shipping. The tiny brass hinges are weak and broke and the inside bent. The drill bits themselves are fine.

Good quality bits, cut easily and accurately (photo). My usual test for cobalt bits is stainless steel, these bits cut through as easily as mild steel. Run them slow, and dip into water periodically to cool off if you have thick material. It’s also a good idea to use Tap Magic cutting fluid to reduce friction, and thus keep the bits cooler. Good price, happy with purchase.

I had a use case where a machine screw had broken off in a location that wasn't easy to access. I decided versus pulling the piece of equipment apart to improve access, I'd spend the money on a set of these with the hopes it would catch as I was drilling out the broken off screw. The screw broke during installation, so I wasn't worried about rust or anything like that, and the roll of the dice paid off. As I slowly increased the size of the bits, one finally caught and backed it out. I replaced the machine screw with a new one and job done. This set saved me about an hour of disassembly and for me, that made the set worth the price. I don't know long-term how they'll hold up, but for me, these will be used infrequently and as I mentioned, they've already paid for themselves, so future use is just money in the bank. The case is nice and the quality seems good, so no regrets here.

Took a chance on these cobalt bits because of how many sizes it includes for the reasonable'ish price. The problem is that the quality is very shoddy. The round ends that spin in your chuck are annoying, but over half of the bits I've used so far chip and break instantly upon first use. I'm drilling annealed un-heat treated 1095 steel. My name brand cobalt bits go through like butter, but these... Some of the bits work fine so far, but it's been more miss than hit. I guess it's nice to have all the odd sizes that are included,and they'd probably work on soft materials, but these are made for drilling metal, and they ain't cutting it.

Surprisingly effective and durable when combined with cutting fluid

Extremely sharp and well made. Incredible value for the cost of these cobalt bits.