
I used them to fit heli coils in a cast iron engine block. Actually they are too good for this application. Drilling a smaller pilot hole would eliminate this problem. I bought 2 in case one got dull or broken but each hole only lasted about 30 seconds with no damage.

Cordless drill driver BOSCH GSR 120-LI (06019G8020/06019G8000)
54 Review

Bit and socket set BOSCH Promoline (2.607.017.322), 26 pcs.
24 Review

๐งฑ Bosch 2607017164 Piece Setter Masonry: Advanced Tools for Precision Masonry Work
20 Review

Tool set Stels Tool set, 1/2", 1/4", CrV, plastic case 94 pcs, Stels, 94 pcs, black
45 Review