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Chapter 9 Flatness Measurements
Setting Up for the Measurement
Planning your measurement grid
To measure the flatness of a surface plate, you must draw the lines along
which you will make measurements on the surface plate. The border of the
grid is determined by whether or not you can align the laser head with
each of the measurement lines by moving the laser head around the
surface plate. Usually, the floor area around the surface plate is clear
enough to allow you to move the laser head from line to line around the
surface plate in order to make measurements.
Sometimes, however, the surface plate is in a corner or has equipment by
it that prevents you from moving the laser head around all sides of the
surface plate. If this is the case, first measure the axes along which you
can align the laser beam. Then, line up the laser head with one side of the
surface plate and use flatness mirrors to direct the laser beam along each
remaining measurement axis.
NOTE
Measurements using flatness mirrors are more complicated and take
longer to perform than measurements without flatness mirrors. Use
flatness mirrors only if it is necessary.
After you have determined whether you will use flatness mirrors, you are
ready to draw the measurement grid.
Determining grid border requirements
In order to properly position the optics on the surface plate, you must
leave a border between the measurement grid perimeter lines and the
edge of the surface plate.
If you can move the laser head to each measurement line, leave at least a
51 to 76 mm (2 to 3 inch) border. The border allows sufficient room for you
to place optics for measurements along the perimeter lines. Figure 9-3
shows an example of a measurement grid with 76 mm (3 inch) borders.
9-6
Measurements Reference Guide
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