The Pittler C3 is unusual in that it has two mandrels, both of which are easily removeable. The Lead-screw pitch of the C3 is 2 1/2" to the inch. In order to obtain an efficient arrangement to take up the back thrust it had been found necessary to make use of a short parallel spindle. This carried the worms on one end and a spur gear on the other and engaged on the same sized spur gear on the headstock spindle.
Above: the two mandrels shown fitted side by side( for demonstration purposes only) at the rear is what Pittler calls the false mandrel. It screws on in place of the back thrust crown when using the dividing spindle. The large thread is for the back thrust crown.
The front or "parallel" mandrel is used for general operations on the lathe but must be removed to use the rear one. When powered up with both mandrels inserted they turn in opposite directions to each other but the rear mandrel should preferably be replaced with the back thrust crown before running the lathe.
Above: at the top is what Pittler calls " the false mandrel " with it's threaded loose sliding collar with a hole for a tommy bar, below it is the front "parallel mandrel" with it's spur gear. Either can be quickly fitted or removed depending on turning requirements. The parallel mandrel is used when the back thrust is fitted on the main shaft so it takes the load off the bearings
Left: the set up for using the indexing spindle which replaces the screw cutting one. The front "parallel" spindle has been removed and a worm wheel fitted on to the false mandrel which replaces the back thrust crown. When using this accessory the lathe has to have the drive belt removed or slackened off the headstock pulley to allow the indexing spindle to freely turn the chuck.
For details of the dividing spindle see here
For spiral cutting- the leadscrew is powered from the tailstock end of the lathe using a belt from the overhead pulley. This turns the leadscrew slowly, dependant on belt speed and worm wheel size to suit the spiral required. The drive power then goes up through the reversing gearbox to the mandrel and finally the chuck.
Above: the front " parallel" mandrels spur wheel can be moved over via a small rack and pinion by using a key that fits on a lug. This feature is not present on some of the lathes made at Wahren and supplied to George Adams.
