The routing portion of a pantograph routing and drilling machine operating on a stack of sheet-metal blanks. Two operatives were required, the one shown on the left guiding the stylus round the templates. In the background can be seen one of the drilling machines which were of similar construction.
For the shaping and drilling of light-alloy sheet metal blanks to a regular consistency, a number of aircraft manufacturers used continuously operating pantograph machines. The complete equipment consisted of a router with two drilling machines and was arranged to work over two parallel tables nearly sixty feet in length. A drilling machine was placed at each end of the tables. Between the tables was a centre rail on which the pantograph unit traversed longitudinally on steel rollers and there were steadying rails at the sides of the tables to prevent the unit from tipping unduly. Rollers were fitted at the extremities of the pantograph to contact the side rails.
The pantograph itself comprised of two carriages superimposed upon one another. Movement of the lower carriage was along the tables on the centre rail, while the upper carriage, which carried the routing stylus and cutter spindle, had transverse movement on slides on the lower carriage. This double right-angled movement was combined to follow the shape of any routing template. A similar arrangement was adopted for the drills located at each end of the tables. The process not only allowed continuous operation, it also created consistant accuracy for a template of known form and dimensions was being followed.
Power traverse to the longitudinal movement of the lower carriage was provided by four motors. Two of these gave left or forward traverse and two right-hand or reverse movement. The motors were controlled by the operator until the stylus made contact with the template, after which the direction of motion and the cutting speed were controlled by hand pressure between the stylus and template.
Drilling and routing templates were mounted on sheets of plywood and secured to one of the tables. Sheet metal blanks were stacked on the other table opposite and when the first few holes have been drilled were pinned in position. The remaining holes were then drilled, after which the profile was routed to shape.
While one stack of blanks was being drilled and routed, templates and blanks were being placed in position at another position along the tables. The second drill was brought into action on these as soon as the first set of blanks had been machined to shape and the routing head was brought along to complete these in turn. In the meantime the second batch had been drilled at the first station, or still another set at a third station, so that work on the machine could continue without pause. Sliding overhead rails carried electric and compressed air supply lines to the machine.