Checking for calibration
Your David White instrument must be serviced and repaired
by an authorized David White service center. You may, however,
choose to
check the instrument yourself to make sure it is properly
adjusted. A simple, inexpensive setup can be established to check
an instrument’s line of sight:
1. Locate an area to set up a tripod that is 10 feet away from a
wall, post, permanent shelving, etc. and approximately 75 feet
to 100 feet away (at a 90° angle) from another wall, post, etc.
2. Using an automatic level or other high-accuracy instrument
known to be in perfect adjustment, secure it to the tripod and
level it following instructions in the instrument’s owner’s manual.
3. Make sure the tripod is on a firm base and mark the location
of the tripod shoe points. These marks can be used for future
reference.
4. After the instrument has been completely leveled, sight on the
wall that is 10 feet away.
5. Place a two-foot section of rod ribbon on the wall so the
horizontal cross hair of the instrument intersects the middle of
the two-foot section.
6. Rotate the instrument 90° and sight on the wall that is about
75 feet to 100 feet away.
7. Place a two-foot section of rod ribbon on that far wall so the
horizontal cross hair of the instrument intersects the middle
of the two-foot section (as in Step 5). Adjust this rod ribbon so
that it reads the same exact point as the closer ribbon. Secure
ribbon with tape or glue.
8. Now put the instrument to be checked on the tripod and take
a reading on the ribbon 10 feet away. Record the reading.
9. Rotate the instrument 90° and take a reading on the distant
ribbon.
10. Compare the two readings. If there is a difference in the two
readings, your instrument needs adjusting by a David White
service facility.
If you have questions about checking for calibration, contact
David White or a repair facility. All actual adjusting of the
instrument must be done by a qualified service facility.