Since then, the original poster, Doug from s.d.ca, has become a frequent and much appreciated visitor who shares his knowledge of air compressors regularly. He has now added some new information about his compressed air can crusher.
In this first photo Doug explains "I've added a spacer for regular 12 OZ cans, and a regulator to the "pull-back" side of the cylinder, set at about 30PSI. "
In this second photo Doug shows the spacer inserted into the can chamber.
Doug goes on to say "Between the two, I save over half the air required to crush a 24 OZ can."
The new spacer limits the cylinder travel when crushing a can, meaning less air is used to do so.
Adding the pressure regulator to reduce the pressure used on the on the cylinder return stroke means that less air is used then as well, both adding up to substantial air savings. Less air used means less energy consumed to compress that air, and less energy consumed means a smaller electric bill.