After completing a part in the lathe it is frequently necessary to separate the part from the excess material used for chucking. This operation is best accomplished with the use of a cutoff tool or "parting tool" as it is sometimes called. The Sherline cutoff tool and holder consists of a very slender high-speed tool steel cutting blade mounted in a special holder. The thinness of the blade (.040"or 1mm) enables it to feed into the part quite easily, and, at the same time, minimizes the amount of waste material. The turning speed for parting should be approximately one-half the normal turning speed for any given material.
One word of caution; never use a parting tool on a part mounted between centers. The part can bind on the cutter and result in a scrapped part or a broken tool. A small amount of cutting oil is a must. Parting off free machining material over a 1.00" (25mm) diameter will always be a problem on a machine of this size because of the thinness of the blade and the difficulty of keeping it lubricated in deep cuts.