BEILI TOOLS HSS M35 Cobalt Twist Drill Bits, Pack of 5 (12.7mm, 1/2")

These drills do a great job on hardended structural steel and 1/4 plate, dozens of holes on the first bit and still sharp. I use oil and cut a slow speed.

I was looking for 8mm but got 5/16 (random?) 5/16 is what's on the package and what they measure out at. I admit that I am being picky here... .0025" or .04mm off is not enough for most people to ever notice. Plus it's very likely to slightly open or over-drill in the real world enough that it will be just a bit closer to right... Yeah I'm really being picky now lol. Bits are clean and sharp and look great. I'd buy again, maybe next time I'll luck out and get 8mm!

This is the go to Drill Bit! WOW! 42 Bucks at Lowe's and All 3 of the Name Brand Bits BURNED UP!!! These went right through the Stainless Steel in seconds!!! I so am going to do a YOUTUBE.COM video to show this! The BiG Name Brands owe me some money!! What happened to truth in advertising? These are TOP CLASS!!! Buy em' and don't look back~!

I drilled 10 holes in 1/2 inch thick 304 stainless with one bit. It was turned at the proper speed and lubricated, not pushed hard. After 10 holes it was starting to dull. Good value in my opinion.

I got these for drilling holes to install self-tapping screws for the rebuild of my trailer deck. I drilled thru 1.5 inches of wood and about 1/4 inch of metal framing for each screw. I needed to put in 60 screws and I figured I would run through 5 or 6 drill bits to complete the job. Well I put in all 60 screws and made a few other holes in heavy metal and I am still on my first drill bit!

Bought these based on the recommendation of a reviewer for the bolts I used to install the floorboards. Broke two total which was A LOT less than I expected to. These were a huge time and money saver as I didn't have to go to the big box store and spend a lot more on individual bits.If you are buying these for a floorboard or similar project, well worth it!! Great set of bits!

Stayed sharp and held up

They are sharp and true. They do have cobalt in the metal which makes them prone to the cutting edge breaking when bound against the last part of the cut. If you are using is a hand drill expect this. I was able to drill though track bolts (grade 8) on the master link. If I kept a close watch on the amount of pressure i was putting on the bit I had no problem with the cutting edge breaking. I never broke a bit except the cutting edge which was my fault,Overall great bit especially for the price.