As carriage 1 travels along guides 2, gear rack 3 rotates gear 4 which is rigidly attached to cam 5. At this, bar 7 with follower roll 6 turns about fixed axis A. Roll 6 is held in contact with cam 5 by spring 8. Slide 9 travels along bar 7 and is pivoted to cross slide 10 which moves in a slot of carriage 1. Gear rack 11, rigidly attached to cross slide 10, meshes with pinion 12 and, through gears 13 and 14, rotates rifling tool 15. Axial travel of rifling tool 15 is accomplished by travel of carriage 1. Thus helical motion is imparted to the rifling tool, enabling it to cut helical grooves (rifling) in the bores of gun barrels.
$2570$LrG,FD$