Countersink Drill Bit Set for Steel, 3 Flute 90 Degree HSS Chamfering Tool Bit for Metal Wood Woodworking Metal Working Tool Bit Set, Pack of 6pcs 1/4 1/2

I'm an old fashion machinist, and learned long ago to drill-counter sink at low speed-300 to 500RPM, when countersinking metal. The harder the material, the lower the speed, to avoid "chattering" of the bit. Soft stuff like wood or plastic can tolerate much higher speed. Trying to countersink metal with a power hand drill, requires a very strong handed He-man.

Very good quality. Highly recommendable.

I bought this to drill some countersink holes in an aluminum plate I bought to use as a heated bed on my 3D printer (713maker).I'm an idiot and used the wrong one to countersink the holes for my standard M3 screws (there's 2 for M3), so that's my fault. However, it got the job done with my Ryobi hand drill as you can see in the pictures.While it did get the job done it did come out a little ugly. However, that could be due to the fact that I used a hand drill instead of something like a drill press. I didn't need it to be fancy, just functional, and for that it worked. I also used some 3 in 1 oil. Wasn't sure if I was supposed to or not, but I've seen other metal shops use oil so I figured why not. The bits went through the aluminum like butter.Can you tell I'm not a metal worker?

Each item in this set came well machined and with perfectly straight shafts.I have used them on both steel and aluminum with good results. They leave a smooth finish that requires no additional “clean up” and none of the pieces shows any wear so far.I did not rate longevity and durability solely because I haven’t had the set long enough. That said the total lack of wear exhibited by the bits so far strongly suggests to me that durability and longevity are unlikely to be an issue. And, to be honest, given that they perform so well, at this price I’m really not concerned about longevity. (As long as they’re still available if I need to replace them of course!!!)P.S. No inducement received for this review.

I used it once on metal L bars and it worked good for the first 5 holes but after that, it smoked and got dull. If you need something for professional use, this is not it.

Good product and good "bang for the buck." More expensive items may be more durable for someone who uses them often, but for the DYI home shop, these do a good job.

I got the Countersink Drill Bit specifically to make countersinks is angle iron. The bits specifically state for metal and I was a little suspicious they may not work but for only $14 for a set of 6 it was worth the risk. I used the 16.5 mm to make counter sink for 1/4 screws. I was pleasantly surprised when I was able to drill 4 countersinks with reasonable effort to get the depth I needed. I used a battery powered 20V drill at a lower speed. The #14 flat head screw seated perfectly in the countersink.

Very poorly made, the cutting edges are all very dull and chipped/gouged.