If you have trouble grinding good tools or if you choose to work with difficult materials such as stainless steel,this Sherline tool holder will bring a great deal more enjoyment to your machining. Manufacturing it from 7075 aluminum, which is approximately twice as hard as regular T6 aluminum, insures a long life for the holder. The carbide insert is designed in such a way that it cuts like a positive rake cutter. Positive rake cutters don't require as much rigidity as negative rake cutters. This type of design allows the advantages of a negative rake cutter (four cutting edges per insert) without requiring the rigidity that can't be found in smaller, bench-type lathes.
Carbide cutters give god finishes on hard-to-machine materials such as cold rolled steel. (They will also work on aluminum, brass or leaded steels, and will last practically forever; however, the best finishes on those materials are still achieved with a good, sharp high-speed steel tool.) The holder comes with one four-sided carbide insert. Replacement cutters are available (P/N 7612). Though not inexpensive, when you consider you are getting four cutting tools in one and are saving a lot of time in tool sharpening it is really a pretty good deal.
7610 Sherline 55 Degree Negative Insert Tool Holder