Gear 3 rolls around fixed gear 4. Drum 1 rotates freely about fixed axis B. Rigidly attached to gear 3 is screw 5 which is connected by a screw pair to annular link 2 which slides along the outer surface of drum 1. Link 2 is a toolhead which carries a clamped boring tool. When drum 1 rotates (main cutting motion), gear 3 rotates about axes A and B, and, by means of screw 5, feeds toolhead 2 along drum 1.
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