1
g021765
Figure 52
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 36.6 m (102 ft).
•
Entry pitch
The entry pitch is the angle at which the machine
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 the entry pitch is, the deeper the bore will
have to be due to the limitations of the pipe flexibility.
Typically you need to insert the drill and at least 1/3 of a
pipe into the ground before you can start steering toward
the beginning of the bore point.
,
,
and the following table illustrate the relationship between
entry pitch and depth.
1
2
3
g021766
Figure 53
1.
26% pitch
3.
76 cm (30 inches)
2.
3 m (10 ft)
2
3
g021767
1
Figure 54
1.
18% pitch
3.
53 cm (21 inches)
2.
3 m (10 ft)
52
