Gears & worms, B2 & C3
Above shows the B2 mandrel fitted with a 5 start worm engaging with a worm wheel fitted on the screw cutting spindle which is shown on the on the right. The worm wheel can run on either the front or rear side of the mandrel on a B2 but only the front on a C3. The gearbox banjo is made to swivel for this purpose. The B2 locks the banjo with a tommy bar but the C3 requires a spanner on a nut
The gear train for screw cutting and power feed is quite different to most other lathes in that it utilises a worm and worm wheel. 17 gears & 3 worms are supplied for the B2 and 20 gears for the C3
On the top left are the three standard and one special worm used for screwcutting and other machining operations on the B2. Three of these were supplied with every screwcutting B lathe, a one start, a five start and a 10 start. The largest one is a non standard 15 start worm which would have been a special order.
For my Pittler B2 the set stamped with the number 1253 comprises 18 wheels. 20,22,24,26,28,30,32,34,36,38,40,48,50,60,80 for multi start and 30,50,80 for single start.
The C3 has 20 wheels 20,24,28,32,36,40,44,52,56,60,64,68,72,76,80,96 in five start and 24,40,72,96 in one start.
A screwcutting chart fitted to the drawer of B2 number 1253
