DRILLFORCE (10 Pcs) 11/64 in. x 3-1/4 in. HSS Cobalt Drill Bits, Jobber Length, Straight Shank, Metal Drill,Ideal for Drilling On Mild Steel, Copper, Aluminum, Zinc Alloy Etc.

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.

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.

Extremely frustrating. I bought these to drill into a steel trailer after the cobalt bit from my Milwaukee set broke thinking 10 bits would get be through (flashing a 7.5’x11’ trailer), but nope, I ordered a whole second set which preform even worse.. the bits ranged. Some snapped the first whole I tried to drill, some snapped in the first 5, the exceptions lasted longer. Also, the first pack I bought predrilled a hole that fit the #8 screws I was using, then the second pack drilled holes that they just slid right into, so inconsistent widths in the bits are another problem I had. Yah get what yah pay for eh.

Reveiw for 1/8th" bits.These come really sharp and hold the edge well. But they are more brittle than higher priced bits. In a drill press at correct speeds these perform excellent. If free hand drilling you have to be careful with speed and pressure. If they "bite" when breaking through the material they snap way to easily.

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.

These things cut through mild steel like a hot knife through butter. Bought 10 and only took the second bit out of the package because I misplaced the first one. I have shot 25 or more holes with the bit and no sign of dulling. Of course, I always use cutting fluid. Why overheat when you don't have to?

These are good quality drills that are properly hardened. I drilled many holes with these and they exceed expectations for drills in this price range. I was originally planning to use them only on aluminum but they drill great in steel too.

we always use 1/8 bits when we drill a pilot hole for #6 screws, when using these bits the hole is slightly too big...they cut great and last put the size is off for some reason.