HAMAR LASER L-708, Operation Manual

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Appendix B – Calculating Bore Diameters
Once the measurements have all been taken, a few simple calculations will provide detailed information
on the internal diameter of the bore. Due to the design of the target and the NORMIN procedure, it is
necessary only to know the reference diameter in order to calculate bore size at each measured point.
To track change in diameter, the user calculates the offset between the target center and the bore center
(the Target Centering Error or TCE) for each point measured. When TCEs from two measured points are
compared, the difference between them is an accurate measure of the difference in their diameters.
Note: These equations apply to any bore target.
1. Calculate the Reference Diameter TCE (RDT).
The target centering error for the reference location using the NORMIN readings taken at the refer-
ence location is the Reference Diameter TCE (
RDT
). The formula is:
RDT = Normal R Inverted Reading
2
2. Calculate the Measured Diameter TCE (MDT).
The target centering error for each measured point using the NORMIN readings from each measured
point is the Measured Diameter TCE ( MDT ). The formula is:
MDT = Normal R Inverted Reading
2
3. Calculate the difference in diameter between each measured point and the reference location.
The difference in diameter between each measured point diameter and the reference location
diameter. The formula is:
(RDT - MDT) × 2
Note: If the result of the above formula produces a negative number larger than that of the RDT,
then the measured point diameter is larger than the reference location diameter.
To find the actual diameter of each measured point, measure the reference location diameter and use
the formula below:
Measured Point Diameter = Reference Location Di (MDT - RDT) × 2
Bore Size Measurement
In this application, the offset represents the RDT for the reference location and represents the MDT for
each measuring point.
Location Normal Inverted Offset Diameter
Reference Location 0.008 -0.006 0.001 4.500 in.
Measuring Point 1 0.012 -0.008 0.002 4.498
in.
Measuring Point 2 0.004 -0.002 0.001
4.500
in.
Measuring Point 3 0 -0.008 -0.004 4.510
in.
Measuring Point 4
Measuring Point 5
Measuring Point 6
Reference Diameter TCE (RDT) = Normal R Inverted Reading
2
Measured Diameter TCE (MDT) = Normal R Inverted Reading
2
Difference in Diameter = Reference Di ((MDT – RDT) x 2)