Set up a line laser so the line means something

Before switching it on

Check the tripod thread against the tool. Set the tripod low enough — most laser work happens between 60 cm (23.6 in) and 150 cm (59.1 in), and a tripod with a 122 cm (48 in) minimum cannot set a line for a skirting.

Spread the legs fully and press them down. A tripod that settles into a carpet or a dust layer after you have marked the first wall has moved your datum.

Leveling

1. Switch on and let the pendulum settle. Most units take a few seconds.
2. If it sounds a continuous tone, the base is outside the self-leveling range — level the tripod head, do not ignore the tone.
3. Mark a reference point on one wall.

The check that takes a minute and saves an afternoon

Rotate the laser 180° on the tripod head, without moving the tripod, and look at where the line falls on the same wall. It should be in the same place. If it is not, the laser has an error and the difference is twice that error.

This is the same turn-over logic as checking a spirit level, and it costs a minute at the start of a job.

While you work

• Do not move the tripod. If you must, re-establish the datum from a marked point rather than from memory.
• Watch for knocks. A self-leveling laser re-levels itself silently after a bump — which is exactly the problem, because the tripod may have moved with it.
• Outdoors, or past a few meters in bright light, use a target plate matched to your diode color, or a receiver.

Laser class

The class marked on the tool — commonly 2 or 2M under EN 60825-1 — is a manufacturer statement, and the precautions that go with it are in the manual supplied with the instrument. Do not look into the beam, and follow what the maker states.