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Given the above information, you can calculate the number of
rods required to reach your beginning point at the appropriate
depth. Toro recommends that you start the entry point a
distance back from your beginning-at-depth point by the
same distance as the length of pipes you will need to reach
that point. This will ensure that you have enough extra space
so you will not need to over-steer and damage the pipes.
1. 26% pitch
2. 76 cm (30 inches)
3. 142 cm (56 inches)
•
You begin steering up for the next 3 m (10 ft), pushing the
pipes in at the maximum pitch change of 8%. This results
in a change of pitch from 26% at the beginning of the 3 m
(10 ft) to 18% at the end of the 3 m (10 ft) for an average
pitch of 22%. Given that, the drill head lowers another 66
cm (26 inches) and is now 142 cm (56 inches) deep.
•
Continuing steering up for the next 3 m (10 ft) at an 8%
pitch change, your pitch will change from 18% to 10%
for an average pitch of 14%. Given that, the drill head
lowers another 43 cm (17 inches) and is now 185 cm (73
inches) deep.
•
Continuing steering up for the next 3 m (10 ft) at an 8%
pitch change, your pitch will change from 10% to 2% for
an average pitch of 6%. Given that, the drill head lowers
another 18 cm (7 inches) and is now 203 cm (80 inches)
deep.
•
Leveling the drill head from 2% to 0% takes less than 1.5
m (5 ft) more for a final depth of 208 cm (82 inches).
Reaching this final point took four and a half, 3 m (10 ft)
pipes. So for this example your entry point should be
14.7 m (45 ft) back from the beginning-at-depth point of
your installation.
The following example illustrates the process given an
installation using the maximum entry pitch of the machine
(26%) on level ground:
•
1
2
Figure 10
4. 185 cm (73 inches)
5. 203 cm (80 inches)
6. 208 cm (82 inches)
14
You insert the first 3 m (10 ft) of drill bit/pipe into the
ground with no steering. The end of the drill bit will be
76 cm (30 inches) deep
(Figure
7
3
4
7. 14.7 m (45 ft)
7).
5
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g021768
6
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