Q1 - What should the calibration cycle of a surface plate be?

A1 - The best method of determining a cycle for a plate is to monitor its change in time. Should a plate for example be calibrated yearly and it rarely falls out of the required grade or tolerance then a longer cycle would be more appropriate. Yet, on the other hand should a surface plate show out of tolerance conditions at each yearly calibration then a shorter cycle would be more suitable. Cycles should be constantly monitored and adjusted regularly depending on use and environment.

Q2 - What is the correct method of mounting a surface plate?

A2 - All plates regardless of size (as per Federal Standard GGG-P-463c) shall be mounted according to the figure shown below.

Should a surface plate be mounted any differently, the surface flatness cannot be guaranteed. Contrary to popular belief, a surface plate does not require to be leveled to maintain its accuracy. If the plate is properly mounted it need not be level unless your specific application calls for it.