Simplifying the measurement of bores

[Frank S]

Marv has given an excellent explanation about measuring bores. I like using adjustable parallels for doing what he describes the problem with them of using telescopic gauges is we humans were unfortunately only have 2 hands. holding 2 objects one in each hand then trying to position those just so. and get true reading of the measurements are sometimes more daunting than trying to take the measurement in the first place. It is next to impossible for me to hold a 4 " mic in 1 hand and and adjust it with the same hand Often I will hold the shaft of the telescope gauges in the alligator clips of a pair of 3rd hands or hold the body of a micrometer in the rubber jaws of a small vice. When ever possible though I measure bores with this.
.0005" graduations plus most bores that I need to check are either tapered or out of round I can tell both by moving up or down or rotating it in the bore. the readings are close enough for anything that I do from 2 to 6 inches