HAMAR LASER STEALTH Series, General Training Manual

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Arc Measurement Method - Sweeping Through the Arc
For hard-to-reach rolls that are farther than 2 ft. (610 mm) from the laser, or where the roll radius is
greater than 2 ft., the Arc Measurement Method must be used to get accurate results. In this method,
instead of using the bullseye level, the target is swept through an arc to find the Top Dead Center (TDC),
or the highest point on the arc that is tangent to the laser plane. To do this, the target is attached to the roll
and it is slowly rotated (or slid around it) until the highest value is determined (see procedure below).
Arc Measurement Method Procedure
1. Set up the A-1519-2.4ZB Target magnetic base (or
use the T-1600 as described below). Ensure that
the level on the magnetic base or fixture is
centered, indicating you are close to TDC.
2. Slowly slide (or rotate the roll) the target magnetic
base (or T-1600 fixture) around the roll in one
direction while watching the R-1356 display. If
you see the target reading decreasing in value, stop
and rotate in the opposite direction. You will then
see the target value increasing . As you continue to
sweep through the arc, you will notice the value
stops increasing for a short time, and if you
continue to rotate in the same direction, then you
will notice the value will start to decrease again.
3. The highest reading (most positive) occurs when
the target is at the TDC. This is the value to record
as the measurement for that point.
4. This method should work for roll diameters or
target rod lengths up to 6 ft. or 2 m.