How to Set Up Surveying Instruments: Levels and Tachometers

Posted on Nov 23, 2025 in Other subjects

Setting Up a Topographical Level

I. Initial Setup

  1. Set up the tripod to a suitable height and firmly secure its legs in the ground.
  2. Open the instrument case and, before removing the level, note its position so you can store it correctly after use.
  3. Place the instrument on the tripod and secure it using the central threaded screw.

II. Identifying Instrument Components

Familiarize yourself with the physical parts of the instrument and their locations:

  • Tribrach
  • Leveling screws
  • Telescope
  • Fine adjustment or tangent screw
  • Image focusing screw
  • Reticle focusing screw (for the telescope’s crosshairs)
  • Horizontal circle (limb)

III. Leveling Procedure

  1. Ensure the tripod legs are firmly planted in the ground, stepping on the feet if necessary.
  2. Roughly center the circular bubble level by adjusting the length of the tripod legs. (Tip: Hold the tripod leg firmly when adjusting the clamps.)
  3. Position the telescope parallel to two of the leveling screws. Center the bubble by turning these two screws simultaneously in opposite directions (e.g., both inwards or both outwards).
  4. Rotate the instrument 90 degrees so the telescope is aligned with the third leveling screw. Use only this third screw to center the bubble.
  5. Return the instrument to its original position and check if the bubble remains centered. If it is, the instrument is level and ready for use. If not, repeat the process.

Setting Up a Tachometer

I. Initial Setup

  1. Extend the tripod legs to a suitable height.
  2. Place the tripod over the survey station point and press the legs firmly into the ground.
  3. Open the instrument case and, before removing the tachometer, note its position for proper storage later.

II. Identifying Instrument Components

Familiarize yourself with the physical parts of the instrument and their locations:

  • Tribrach
  • Leveling screws
  • Telescope
  • Horizontal fine motion (tangent) screw
  • Vertical fine motion (tangent) screw
  • Alidade clamp screw
  • Vertical clamp screw
  • Optical plummet
  • Image focusing screw
  • Reticle focusing screw (for the telescope’s crosshairs)
  • Horizontal and vertical circles for angle reading
  • Illumination mirror for angle readings
  • Circular bubble level
  • Tubular (plate) level
  • Optical sight (sighting collimator)
  • Main clamp lock

III. Centering and Leveling Over a Station

  1. Position the tripod over the survey station, ensuring the legs are secure.
  2. While looking through the optical plummet, adjust the tripod legs to center the instrument directly over the station marker.
  3. Roughly center the circular bubble level by adjusting the length of the tripod legs. (Tip: Hold the tripod leg firmly when adjusting the clamps.)
  4. Position the tubular bubble level parallel to two of the leveling screws. Center the bubble by turning these two screws simultaneously in opposite directions.
  5. Rotate the instrument 90 degrees and use the third leveling screw to center the tubular bubble.
  6. Return to the original position, check the bubble, and then look through the optical plummet to ensure it is still centered over the station marker. If both the instrument is level and the plummet is centered, it is ready for use. If not, you may have one of the following issues:

Troubleshooting Common Issues

  1. Problem: The instrument is level, but the optical plummet is slightly off the station marker.
    Solution: Loosen the central screw slightly, slide the entire instrument (without rotating it) until it is centered, and then re-tighten. Re-check the level and repeat if necessary.
  2. Problem: The optical plummet is centered, but the instrument is not level.
    Solution: Repeat the leveling procedure (steps 4 and 5) carefully.
  3. Problem: Both the level and the centering are significantly off.
    Solution: It is best to restart the entire setup process from the beginning.