Check Plumb

Place the PLS 480 on the standard floor base and position the PLS 480 so that the down point is visible on the floor. Mark the down point position and without moving the laser also mark the intersecting point at which the two vertical lines meet on the ceiling.

Turn the laser 180 degrees and place the down point on the original mark on the floor. The intersecting point on the ceiling should match the original ceiling mark. If there is a difference between the original ceiling mark and second mark, the error of the plumb beam is half that difference. Check Level

Choose two interior walls approximately 15'-0" apart (see Fig. 1).You can use 2 x 4s for targets.

Turn on the PLS 480 to Level setting #1 (level). With the PLS 480 six inches away from and facing target #1, carefully mark the center of the line. Label this mark A1. Swivel the laser 180 degrees and mark the center of the line on target #2. Label this mark B1.

Move the PLS 480 six inches away from and facing target #2. Carefully mark the center of the line. Label this mark B2. Swivel the laser 180 degrees and mark the center of the line on target #1. Label this mark A2.

You now have two centers of elevation at each target. Carefully measure the distance between centers of each set of marks. If there is a difference, subtract one measurement from the other. This calibration method magnifies any error by a factor of two. Therefore divide any difference by two to find the true error.Your PLS 480 should have an error of no greater than 1/8in. within 60ft. Check Square

Checking the PLS 480 on the job site using Pythagoras 3-4-5 Triangle: