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Figure 41
1. 20 cm (8 inches)
This flexibility is often rated in materials as a
minimum bend radius, which is the radius of the
circle formed if the material or pipes, connected
together, were bent to form a giant circle. The
minimum radius of a circle made with the pipe
used with this machine is 31 m (101 ft).
•
Entry pitch
The entry pitch is the angle at which the drill bit
enters the ground. With the tracks on level ground,
the stabilizers down, and the stake-down plate
on the ground, the drill frame angle is about 15
degrees or a 27% pitch. This pitch will change
depending on the slope of the ground and other
factors of the job site. You can also reduce this
pitch a bit by building up the ground under the
stake-down plate before positioning the machine.
You can determine the actual pitch of the drill
frame by placing the drill bit and sonde housing
on the frame and then use the receiver to display
the pitch.
The steeper your entry pitch is, the deeper your
bore must be due to the limitations of the pipe
flexibility. Typically, you need to insert the drill bit
and at least 1/3 of a pipe into the ground before
you can start steering toward the beginning of the
bore point.
Figure
42,
table illustrate the relationship between entry pitch
and depth.
Figure 42
1. 26% pitch
2. 3 m (10 ft)
Figure
43, and the following
3. 76 cm (30 inches)
g021765
1. 18% pitch
2. 3 m (10 ft)
g218953
40
Figure 43
3. 53 cm (21 inches)
g218953
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