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.

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 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.

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?

Very good quality. Highly recommendable.

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.

China made parts through a Canada branded company. Poor quality, too soft tool steel used in bits. Tried to countersink a 5/16” hole to yield an outside 3/4” diameter in 304L SS. Used the large bit in the set on a large heavy 14” lathe. Bit struggled to cut the SS. Ended up making a lathe tool and used the compound cross bar to fit the mess this bit produced. Returned then. Poor quality using a too soft metal for the tool. Might be good for brass or aluminum.

I used these initially with a hand drill, got some chatter and overall poor finish. Chucked it up in my bridgeport though and cut some 1045 very smoothly and nice. No chatter, very nice finish.

After few months in my drawer I have discovered that these countersink bits are ineffective in cutting a countersink into cedar, let alone a hardwood or ply. I can't call them blunt, because they haven't been used. It seems that the cutting edge hasn't been manufactured to stand proud of the leading edge such that the tool can cut into material effectively.