Also, as all movement is on ball bearings, this will give less torque requirements than needed by the plain bearings. Another change was to use cable that is used on parallel bars for drafting tables rather than the fishing line used in Steve's design. The reason for this was simple .I had it in my junk box. Another change was to the interface to the parallel port. I used a 74HCT14 IC from Radio Shack with pull-up resistors on the inputs instead of the discrete transistors and this was wire wrapped board that is fitted into the computer case.
Power is pulled from a spare connector in the computer.
Below, are some pictures of my setup along with a picture of the design of my blocks. An exploded view of the Z axis encoder block. The others are similar. The blank plate is shown on the right side of the block. Originally, I tried to make a block that was solid on this side.