How to Set Up a Tribrach Above a Known Point.

Setting up an optical plummet or laser plummet on tribrachs or instruments can be quickly achieved in a few easy steps.

• Locate your desired reference point that you wish to set up above.
• Extend the legs of the tripod until there is about 150mm of travel left and lock the legs off.
• Set the tripod roughly above your reference point and tread the legs into the ground securely. The top of the tripod should be roughly chest level.
• Place the tribrach on the tripod and secure with the locating screw.
• Look through the plummet or at the laser dot and using the foot screws on the tribrach adjust until the cross hairs or laser dot are over your reference point.
• Look at the circular vial on the tribrach and adjust the legs of the tripod until the bubble is once again in the center.
• Look through the plummet or at the laser dot and this should still be over your reference point. If not, then loosen the center screw and move the tribrach and check the circular vial again. Adjust using the foot screws to get the bubble in the center, if required.