Choose the accuracy and readout needed – don’t select .0001" (0.001mm) readout if .001" will do the job.
Electronic/ Digital styles are best when the measurement data need to be collected, printed out or stored for future use.
Basically, all dial indicators used worldwide fall into the following size ranges which relate to bezel diameters: Size 0 is a smaller dial indicator, having its own dimensions. Sizes 1 through 4 are AGD sizes. These sizes and the AGD dimensions are essentially the same for all manufacturers, except as noted.
Accuracy: All indicators should be “loaded” 1/8-1/4 of a turn before testing or measuring. Most accuracies are specified plus or minus one graduation over the full range. This basically means a 2 ½ turn range. Longer ranges have slightly wider tolerances. AGD specifies 2 1/3 turn indicators to cover any particular range. The reason for this is an effort to get the most out of the indicator – the operator “loads” it to about 1 1/3 turns and sets zero on the master. The indicator will now show the accurate deviation for a full revolution, plus or minus.