HSS stands for high-speed steel, alloyed with tungsten, molybdenum, chromium and vanadium, with cobalt grades such as M42 for more heat resistance. It is tougher and cheaper than carbide and can be ground by hand on a bench grinder to any shape, but it runs at roughly a quarter to a third of carbide's cutting speed. It is the standard material for taps, small drills, form tools and manual lathe bits.
Grind an HSS bit for the radius, it'll take you ten minutes and you won't have to order a special insert.
Also heard as
- high-speed steel
- high speed
Related terms
SFM
Surface feet per minute: how fast the cutting edge moves across the work, the basis for spindle speed.
Blue chips
Steel chips that come off straw to dark blue from heat, read as a sign of how hard a cut is running.
Endmill
A rotating cutter with teeth on its end and sides, the main tool for milling slots, pockets and profiles.
Insert
A small replaceable carbide or ceramic cutting tip clamped in a holder, indexed to a fresh edge when worn.