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The cross-slide is adjusted until swivel pin is in line with the lathe centers, and the carriage is moved along the bed until the horizontal distance between center b of the swivel, and the face of the work, equals the desired radius of the concave surface.

The alignment between the swivel pin and the lathe centers can be tested by taking a trial cut; if the swivel pin is too far forward, the tool will not touch the turned surface if moved past center c, and if the pin is too far back, the tool will cut in on the rear side.