90 Degree HSS Chamfering Tool Bit

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.

Great tool for the price

Chatter is hard to control with 3-flute countersinks, so using them results in polygonal holes rather than round holes when used at high speed. Also, standard bolts tend to use 82 degrees rather than 90 degrees. Otherwise, a great tool for rough work.

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.

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.

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.

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.