HOW TO SET 90° SQUARING
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Working Example
The following description in this guide, explains the general principles of setting-out 90 degree
squaring when using the FRE-203XT. It speeds up the classic 3/4/5 triangle method, giving better
accuracy and alignment over much longer distances.
Equipment
You will need the FRE-203XT laser level, the laser detector (receiver), a target plate and
preferably a remote control. You do
not
need a tripod or staff .
Site Conditions
There are many diff erent work site scenarios. As an example, we are assuming that you have
laid a concrete pad or completed your strip foundations (footings) and are ready to set out in
one corner, 90 degree (squaring) for brickwork, blocks or timber framing, over a datum *mark*.
Procedure
Place the FRE-203XT in
“lay-down”
over your corner datum *mark*, on the concrete surface &
switch ON. Wait for it to auto (self) level, then press and
hold
the On/Off
button for
5
seconds until
the “
hand
”
appears on the display. The self levelling mechanism will then have been turned off .
As this procedure is using “alignment” rather than “levelling” it is more convenient to use the
laser in its Manual mode.
Next, remove the bracket from your laser detector. Switch the detector ON and lay it on its SIDE
over a distant mark along one side of the concrete slab or strip footing. The pick-up window
must be facing the rotating beam of the laser level. Using the remote control, press X/Y button
ONCE, then the MINUS or PLUS buttons to direct the spinning beam to receive a continuous
audible tone on the detector. This has aligned the laser beam exactly on the distant mark.
Next, observe the laser dot projecting from the rotating prism. This is now parallel with the
concrete slab or footings along the other axis. Laser prisms are optically cut to split one laser
beam - to accurately set 90 degrees. i.e. Rotating beam in one axis and laser dot in the other,
setting squaring.
The laser dot
cannot
be picked up with your detector. You need a target plate.
Our recommendation is to use a small piece of around 300mm long white contiplas board, 6- 9
ins wide or similar. Using a black marker pen, draw a vertical line down the middle of the board.
The white surface is an ideal target to “pick-up” the red dot at distance, even in bright sunlight.
Hold the end face of the target board down onto the concrete footings, align the dot onto the
black line and mark the concrete accordingly at appropriate intervals.
This has set 90 degree squaring.
User Tip
Do not mount the FRE-203XT in “lay-down” on a surveying tripod. It must be positioned directly
onto the working surface. If mounted on a tripod, it can potentially introduce an error or
inaccuracy to the 90 degree squaring procedure.
