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How To Use a Bore Guage

Engine Building Fundamentals

Discussion and questions related to the course Engine Building Fundamentals

Page 1

I have a very basic question about reading a bore gauge. What I am confusing myself with is whether my reading is negative or positive. How do you know if you should add the measured distance to the baseline measurement that was used to zero the guage or conversely subtract? Do you subtract if the needle moves past the 0 mark in the direction of needle travel?

Duh moment. I figured it out. I just set my micrometer two thou smaller than the reference and then measured that with the guage and observed the dial. It indeed is smaller that the reference if the needle moves past the 0 in the direction of needle travel.

Sorry for the slow reply, however you can tell if the measurement is larger or smaller simply by watching the dial gauge. If the dial indicator doesn't quite come to zero then the measurement is larger and if it goes past zero, it's smaller.