How to Align a Prism Rod Bubble Using Vertical Alignment on PLT

• Trust your measurements
• Reduce layout errors
• Work faster without second‑guessing results
• Maintain consistent accuracy across the jobsite

General recommendations before leveling

• If you are checking or adjusting multiple leveling bubbles, attach all of them to the rod at the same time.
  This makes the process faster and ensures all bubbles are aligned consistently.
  • Additional Hilti leveling bubbles include the POA 36 Ball Knob () and POA 37 Bubble Adapter ( )
• Place the leveling bubbles higher on the rod, where they are easier to see and adjust.
• Only use leveling bubbles that have adjustment screws.

 Some bubbles have no adjustment screws. These cannot be calibrated and may not be accurate. Always use bubbles that allow adjustment.

Adjustment screws located below the level bubble

Understanding the adjustment screws

• Each screw tilts the bubble toward its own direction
• Small adjustments make a big difference
• Over‑tightening can damage the bubble or throw it out of level

Method 1: Leveling the prism rod using PLT Vertical Alignment

Demo:

Setup

• Attach two prisms to the rod:
  • One near the bottom, fitted with a staking tip
  • One near the top of the rod
• Attach the leveling bubbles to the rod
• Place the rod on firm ground

Procedure

1. Place the prism rod as upright as possible
2. On the PLT, open the Align Vertical application
3. Measure the bottom prism
4. Move to the top prism
5. Watch the live deviation readings
6. Adjust the rod until the deviation reads:
   • 0.000 m, or
   • As close as possible (for example 0.001 m)

Adjusting the bubble

1. Use an Allen key to slightly loosen the adjustment screws
2. Tighten the screws one by one until the bubble centers
3. Make small adjustments only
4. Once centered, gently secure the screws without shifting the bubble

Method 2: Leveling the prism rod using a laser

Setup

• Use a point laser, for example PM 2‑P
• Find a doorway, window opening, or similar vertical space
• Place tape at the top and bottom of the opening

Procedure

1. Place the laser so it projects vertically through the space
2. Mark the laser point on the tape at the top and bottom
3. Remove the laser
4. Extend the prism rod fully between the two marks.
   • For precision, you likely would prefer to screw an additional prism rod tip (POAW45) to the top of the rod, if available ()
5. Adjust the rod until it aligns perfectly with both points

This method helps keep the rod stable as the screws for the bubble are adjsted.

Adjusting the bubble

1. Loosen the bubble adjustment screws
2. Adjust each screw until the bubble centers
3. Secure the screws carefully

Final checks and best practices

• Recheck the bubble after tightening the screws
• Periodically verify bubble accuracy, especially after:
  • Dropping the rod
  • Transporting equipment
  • Long periods of use
• Always level the rod before staking points

Additional reference