Thread: Calculating values which can be plus or minus

I have to setup a girth gear on a large ball mill. before starting I need to check the mounting flange run out using two (2) dial indicators, A and B.

The readings from the dial indicators can be plus or minus depending on the direction of movement of the dial indicator.

The general rules are:When the stem of indicator A is pointing or moving in the same direction as indicator B, subtract the values entered in B from A

and When the stem of indicator A is pointing or moving in the opposite direction as indicator B, add the values entered in B to A

Just repeating that the value A or B can positive or negative.

So what I am after is a guide to show me how i can calculate the values for A and B when the indicator move in the same direction and also calculate their values when they move in opposite directions. For example

Indicator move in the same direction A= 0.2mm, B = 0.4mm = 0.2 - 0.4 = -0.2mm
Indicator move in the opposite direction A = 0.2mm B = -0.6mm = 0.2 + -0.6m = -0.4mm

Marcel with thanks

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