When leveling over the angle point, loosen the horizontal clamp screw.

When leveling over the angle point, loosen the horizontal clamp screw.

• A. Vertical clamp screw
• B. Horizontal clamp screw
• C. Tripod screw
• D. Fine motion screw

Answer: (B)

Leveling over the angle point requires the instrument to be freely adjustable in the horizontal plane. The horizontal clamp screw controls that horizontal movement, so loosening it lets the instrument rotate around the vertical axis to bring the level and sight line into proper alignment with the angle point. When the alignment is achieved, the screw is tightened to lock the horizontal position. The vertical clamp screw would lock tilt up or down and isn’t used for moving horizontally. The tripod screw is just the mounting thread for attaching the instrument to the tripod. The fine motion screw provides very small, precise adjustments once you’re already roughly aligned.

Leveling over the angle point requires the instrument to be freely adjustable in the horizontal plane. The horizontal clamp screw controls that horizontal movement, so loosening it lets the instrument rotate around the vertical axis to bring the level and sight line into proper alignment with the angle point. When the alignment is achieved, the screw is tightened to lock the horizontal position.

The vertical clamp screw would lock tilt up or down and isn’t used for moving horizontally. The tripod screw is just the mounting thread for attaching the instrument to the tripod. The fine motion screw provides very small, precise adjustments once you’re already roughly aligned.