10PCS,17/64", Cobalt Drill Bits

I was reaming holes in 11ga stainless for pop rivets and melting box store bits. Yes, I used a little oil on these. Yes, I broke a few. But they were sharp, well machined, the advertised diameter. Good bits.

Used bits to drill through 1/4 inch mild steel while replacing wooden decking on my 20 ft car hauler. I orders the 10 pack thinking I would dull or break some while drilling the 100 holes. No I have 9 brand new bits left and the only one I used still cuts like it’s new . Best bits I have ever used

Works as expected

Be careful with these bits they might work great on shallow holes, but I was drilling 1.25 inch holes on aluminum, 1/8 depth at a time backing them out and cleaning the bit and lubricating with WD40, had two broken bits that towards the end of the whole, which means dealing with about an inch on drill bit stock on a hole. Never an issue with harbor freight titanium bits. So even as these are sharp and cut aluminum like butter, they are brittle and if they bite more than they can chew you'll have a broken bit. So I would use them for shallow holes never over one inch at this thickness.

I bought these to drill some some holes in titanium because the supplied drill I was given only lasted thru two holes and I needed to drill 5 total. And if you know how titanium gets with a dull drill bit it starts to harden and these drill bits I was able to drill thru the hardened titanium and the remaining two holes with no issues. For the cost these were worth every penny, especially where I figured I'd have to you all of them to finish the project where the 1st drill bit I used was a 40 dollar drill bit.

Excellent back up drill bits if you do a lot of work drilling in both wood and metal. Drill bits are basically disposable - they have a work life and then they are shot. Rather than pay $5 each for replacement bits for your set, buy a pack of these bits and replace them when they wear out, toss. I've tried to re-sharpen drill its with minimal success because invariably, I've over heated the bit and it's lost it's temper and toughness so now I just chuck them and grab a new bit from these multipacks.

used for trailer floor, thur 1/4 channel and 3/16 angle iron, drilled 150 holes, not one broke, thought i would use at least 4 or 5, but only used 1. its still drilling to...great.

A word to the negative reviews calling these brittle, they are specifically designed alloy meant to maintain higher hardness at higher temperatures. Higher Hardness = less toughness, think of the difference between glass and rubber. One is tough, one is hard. Steel is treated to have the ideal mix of hardness and toughness. IF you are just looking for a bulk pack to drill pilot holes in wood, these might not be the ones for you, because they won't flex without breaking like cheaper bits. I am personally on the first one still after drilling 50+ holes, including some through annealed (soft) high carbon steel. Pro tip: Use some drilling oil if you are drilling through anything thicker than 1/8 inch.