Needless to say, slotting the head of a miniature screw and parting it off from bar stock was no easy matter to automate and involved some ingenious and well-thought-out mechanisms. After parting off, the screw was supported in a tiny tube on the end of a swivelling arm that brought the screw in front of a circular saw (driven from a belt at the rear of the machine) - but with an interesting refinement: a little spring-loaded brass pressure sheet with a slot in its front (just wide enough to allow the saw blade through) imposed between saw and screw. The effect of the brass sheet was to push the screw firmly onto its seat and so allow the slot to be made cleanly. After this action, the arm moved backwards, a rod pushed the screw out of the screw-holding tube (a little plug into the tube is seen on one picture) and the  finished part tumbled down a brass slide into a hopper. Two cams were used, one to move the arm forwards and backwards and the other (a face cam) to give a swivelling action - the end position of which was adjustable using stop-screws. As the operation was always identical, the cams were made as one unit and, being highly stressed and prone to wear by an especially long (swivelling) arm, the tappets (followers) were fitted with rollers.
Screwcutting
Rotating clockwise -  viewed from the tailstock end - the spindle of the Petermann No. 0 (in a typical, time-saving design) did not need to stop as the initial part of a threading operation took place. Instead, this was achieved by rotating the die in the same direction as the spindle - but at a faster rate of course - and causing the thread die to press against the job until it cut and began a self-guide. Only then did the spindle stop and allow the die to be reversed off. The apparatus was activated by two cams: the first caused the die-holder to rotate by pushing the belt onto the coupled pulley and simultaneously loosing the brake-band; the second caused the die-holder to be pushed against the workpiece. A shim was positioned on the back of die-holder spindle that touched the lever holding the belt guide, when loosened the spring-loaded belt guide pulled the belt onto the  loose pulley and tight around the brake-band - and the threading operation was completed.
Because early Petermann machines had no separation of chips and workpieces, they had to be sorted afterwards by hand, a job often entrusted to young girls..

A little spring-loaded brass pressure sheet with a slot in its front (just wide enough to allow the saw blade through) imposed between saw and screw. The effect was to push the screw firmly onto its seat and allow the slot to be made. After this action, the arm moved backwards, a rod pushed the screw out of the screw-holding tube.