MANUAL – REFLEX EZ-TRAC™ | 65
10.5.1.2 Position for zeroing – Magnetic Tool Face
The magnetic method shall be used for boreholes that are within 5
degrees from vertical. The instrument should be positioned in a north-
south direction when the zeroing is performed.
The instrument has to be positioned away from any magnetic
disturbance when the zeroing measurement is performed. It is also
very important that the operator does not wear anything that can
interfere magnetically with the measurement.
A reference mark on the outside of the REFLEX EZ-TRAC™ instrument
has to be defined. When the zero position has been established, this
reference mark on the instrument shall be orientated in line with the
mule shoe slot. Since three aluminium extension rods – which make
up a quite long distance – are to be placed between the
REFLEX EZ-TRAC™ and the mule shoe, you will need a method of
aligning the two items.
Figure 77 Position for zeroing – Magnetic Tool Face
Position for zeroing – Magnetic Tool Face
1. Use a compass to set out a string pulled tight between two points,
so that it lies exactly in a north-south direction.
2. Thread the bull plug onto the mule shoe.
3. Remove the bottom nose from the instrument.
4. Thread the bull plug, with the mule shoe attached, onto the
bottom of the instrument.
5. Remove the top coupling of the instrument.
6. Stand the instrument assembly vertically upright, close to the
string.
7. Rotate the instrument so that the open face of the mule shoe is
parallel with the string and the north direction. A wooden stick or
measuring ruler in the slot of the mule shoe may help with this
alignment.
8. Make a mark, which is in line with the mule shoe slot, on the
outside of the
REFLEX EZ-TRAC™. This mark is required as a
reference when assembling the survey system with aluminium
extension rods.
9. The instrument is now ready for the registration of the zero
position. Continue to the section Register zero position.
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