How all those holes get drilled
The machine in action. It takes 64 minutes to complete a strip with the closest spaced holes (7/64″ on center) and 34 minutes to drill the strip with the widest (13/64″ on center). The machine can be left alone to run and shuts itself off when a strip is completed.
A view of the entire machine. It is slow and inefficient but very dependable. A motor, speed reducer and two pulley reductions bring the driving crank (the top is just visible with a spring and cord attached) down to a speed of one revolution every 26 seconds. This drives the indexing and drill feed mechanism by the use of cords and weights. At the beginning of each cycle a cord pulls the indexing mechanism to advance the pin strip a precise distance. After the indexing wheel hits a stop the cord continues to pull forcing the chuck and bit down to drill a hole. To complete the cycle the process slowly reverses, allowing the drill to lift and resetting the index before beginning the next cycle. I have been using it for about 35 years with very little maintenance and with very little scrap produced.
The indexing/feed mechanism is driven by an ancient motor coupled with a used industrial speed reducer that I picked up at a rummage sale for $5.00.
A set of pin strips showing the hole spacings.