A simple way to index on a minilathe is to make use of the change gear supplied with the lathe. As the header picture shows if a gear is securely fastened to the lathe spindle then it is easy to rotate the gear in specified increment. For instance with a 60 tooth gear division by 2, 3, 4, 5, 6, 10, 12, 15, and 30 are all possible.
The shaft is a thin walled tube that is expanded by the two cones at either end. This ensures that the cones are co axial with the spindle. The yellow bar at the top of the picture is the detent bar. This is fixed to the top of the headstock using M4 screws. The head stock is drilled and tapped to accept the screws.
The drilling and tapping into the headstock casting must be carried out carefully since the headstock gears are immediately underneath. The drill and tap was coated with grease to catch the swarf..
The drilling and tapping into the headstock casting must be carried out carefully since the headstock gears are immediately underneath. The drill and tap was coated with grease to catch the swarf..
This shows the shaft dis-assembled. From the left are an M6 nut, a washer, the gear, the first cone with a key for the gear, the expanding tube and the end cone with an M6 stud.
The indexer is very quick to set up. It is simply inserted in the rear of the spindle with the appropriate gear attached to the loose cone and then the nut is tightened to expand the shaft. The detent bar can be left attached to the headstock since it does not interfere with the normal functioning of the lathe.
At a later date a more versatile indexer using a worm gear was constructed. To make this I needed to use the simple indexer to graduate the thimble of the new unit.
The indexer is very quick to set up. It is simply inserted in the rear of the spindle with the appropriate gear attached to the loose cone and then the nut is tightened to expand the shaft. The detent bar can be left attached to the headstock since it does not interfere with the normal functioning of the lathe.
At a later date a more versatile indexer using a worm gear was constructed. To make this I needed to use the simple indexer to graduate the thimble of the new unit.