P-32+ and P-32 Operator’s Manual P/N: 1001547-01
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Sonic stringline provides an inexpensive, easy to set up, continuous reference that takes the best advantage of the
non-contacting feature of the Sonic Tracker. Stringline takes a few minutes to setup, and becomes a constant grade
reference. The stringline also becomes a visual reference for the job, allowing any mistakes in a hub elevation to be
quickly spotted by sighting down the string.
Sonic stringline is both a reference and an averaging solution.
•As a reference, surface and elevated stringline provides consistent results for level and sloped surfaces.
•As an averaging solution, surface stringline takes the place of averaging skis.
The sonic stringline setup consists of readily available materials and up to 500 feet of nylon stringline. Topcon’s Sonic
Tracker works with many sizes and types of stringline, for best results use an 1/ 8 inch diameter nylon stringline.
For a review of how the Sonic Tracker works, see “Sonic Control” on page 14. I f the Sonic Tracker tracks the ground
but not a 1/ 8 inch diameter stringline, clean or replace the transducer. See Chapter 7 for this procedure.
Setting Surface Stringline
A surface stringline provides a low-impact reference and averaging solution for steering and grade control. Because
it rests close to the surface, trucks and other traffic can drive over the stringline without causing control problems
and reference damage.
As a grade reference, pavers use the Sonic Tracker to track the stringline, producing a consistent and constant cut.
When sighting down the stringline, problem areas can be spotted, and marked or fixed, before paving begins.
Surface stringline replaces a contacting averaging ski when a reference is unavailable or impractical. Averaging skis
average out the irregularities of the surface being cut, but can be impractical, bulky, complex, and fragile. Surface
stringline is simple, more practical, and easier to maintain than an averaging ski. When stretched over the ground,
surface stringline levels the high places and bridges the low (Figure 152), creating a natural average over a distance
as long as 500 feet.
Figure 152: Surface String Averaging
A surface stringline is a verifiable reference for any job, replacing cumbersome averaging skis. In coordination with
the Sonic Tracker, stringline acts as 5 to 500 foot long, virtual, and more accurate, averaging ski.
Using steel wire or a plastic coated stringline with a smooth surface can provide erroneous
The ST-3 is not capable of using a surface stringline. Only use a surface stringline when using a
Sonic Tracker I I .
Low Spot High Spot