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With a centre height of around 4 inches and a between-centres capacity of around 15 inches, this simple lathe is of the plain-turning type that lacks backgear but fitted, surprisingly, with chase screwcutting. Simple in principle and easy to use, chase screwcutting has been used on lathes since the middle of the 19th century and frequently employed by such as optical instrument makers, who needed a short but very accurately formed thread.High-resolution Pictures--may take time to load
In its simplest form a master thread (also referred to as a hob or leader) is attached to, or made to rotate with, the headstock spindle while a guide, held in contact with it, transmits the motion to an adjustable cutting tool engineered so that it can slide along a separate arm and impart a copy of the thread to a workpiece held in a chuck or between centres. Fuller details of this system can be found in the writer's article here
Looking otherwise rather ordinary - with a flat and V-way bed instead of the more usual flat top with bevelled edge - the lathe has a screw-feed compound slide rest, though this has only three widely-spaced gip-strip adjustment screws and lacks the very long-travel top slide necessary on this type (as there is no carriage feed, the maximum length of cut being limited by the slide's travel).
One clue to the fact that the lathe was constructed to a decent standard is the method of clamping the tailstock spindle, this being by (instead of a crude slot in the tailstock body closed down by a bolt) the "split-barrel" method with two upper and lower shaped clamps closed by a screw thread.