HSS M35 Cobalt Twist Drill Bits, Pack of 5 (8mm, 5/16")

I purchased these for drilling out 7075 Aluminum 80% Lowers prior to milling. These bits are awesome. I am still on my first bit having drilled many holes and it's still sharp. Previously, I have used a number of other drill bits and often could drill about 4 holes before the bit needed sharpening. So, when cutting a lower I had a number of them and rotated through them and then resharpened them. If you are planning to drill aluminum I highly recommend these bits.

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.

Great Bits for drilling steel plate. I drilled 244 5/16" and 196 3/8" holes through 1/4" steel plate with 4 bits. Went too fast and didn't use adequat oil on the first two. Then I slowed drill down and alternated between cutting oil and 40 weight.oil. Worked perfect.

I've used every bit in the box and they were all straight. That's relatively uncommon for inexpensive drill bits in my experience... They're fairly sharp and had no issues drilling through the resin I typically am machining. Sharpen easily on my drill doctor once I feel they are getting a little dull. Over all a pretty safe option if you're looking for bits.

Drilled 1 hole in mild steel with lube and the bit was dull.Kind of like dating your sisters friends one and done.

I am building a rock rake and needed to drill 56 holes in angle iron. One drill bit did it no problem. I did us a lot of oil during the process.I do not leave many reviews but this perform good enough to leave a review.

Great bits. Used for tailstock drilling on my metal lathe. They are straight (a small miracle in today's China import world) Chips clear well. I will buy this brand again.

These are supposed to be good bits.I gave it 2/5 stars because only 2/5 bits are decent. The rest lost their edge ridiculously quickly while drilling Aluminum. I'm just glad I didn't need them to cut steel.