Measure Cylinder Wear without a Micrometer

Step 3: Drill-end-to-end

A steel rod in two sections will run the length of the block.  It is necessary to drill a hole-end-to-end.  Choose any scrap small diameter steel rod.  A piece of wire from a coat hanger will do.  Drill a hole just a little larger than the diameter of the wire so it can move in the hole easily, but without being sloppy.

I made guide lines in pencil and drilled by hand.  Because bits this size are short I had to drill from each end to make a hole that runs the full length of the block.  Happily, my holes met in the center.  Even if they do not meet, this device will still work, but the holes should at least be close to meeting.