Download a simple, free CAD (computer aided design) program if you are laying out a complicated floor design; allycad.com provides a free home version of their easy-to-use design software, complete with tutorials. Install the program on your computer and take some time to familiarize yourself with the software. After about an hour's tuition you will be able to lay out a complicated floor engraving design. The drawing will be fully dimensioned, with all coordinates provided. For example, if you want a geometric design enclosed in a circle in the middle of the room, the drawing will provide the central pivot point and radius, so that you can set up your circle cutting attachment accurately.
Mark out the geometric design and/or tile pattern onto the concrete. This can be done with a fine-tip felt pen and a straightedge, or you can stretch a chalk line across the floor and snap guide lines onto the surface. Since the blade will not reach into corners, enclose the design inside a decorative border a suitable distance from the perimeter walls.
Remove the blade and slide the circular saw into the slots on either side of the saw cart. Tighten the two Allen-head bolts onto the saw base with an Allen key. Turn the saw on its side and fit a diamond-tipped cutting blade onto the arbor. The blade will extend a short distance from the bottom of the cart to engrave a shallow cut into the concrete. Adjust the pointer wheel extending out from the front of the cart so that it lines up perfectly with the saw blade.
Replace the narrow wheels from the cart with stable extra-wide high-traction wheels. Place the guide wheel onto the first straight mark with the saw blade resting on the cut line a foot or so from the border. Raise the blade slightly by tilting the cart onto the front wheels. Turn the saw on. Lower the blade onto the line until it has cut down to its full depth. Press down while pushing the cart along the line to complete the first straight, shallow cut. Keep the guide wheel on the line during the cut. Stop the saw when the front edge of the diamond blade reaches the opposite border. Turn the cart around and complete other straight cuts in the same way.
Engrave a circle by first consulting your CAD layout and carefully measuring the distance from both the front and side walls to the center of the arc. Mark this point on the floor. Replace the wide wheels on the cart with the standard narrow polyurethane non-marking wheels. Place the base of the circle cutting attachment over the center pivot point of the circle or decorative arc. Insert the extension arms into the center rotating clamp on the circle cutting attachment. Screw the end of the extension arm into the threaded hole in the base of the saw cart. Adjust the arms to the desired cutting width and tighten the clamp.
Kneel on the base during the cut or have a helper stand on it to prevent movement. Tilt the saw cart until only the front wheels are resting on the floor. Move the cart around the full circle without turning the saw on to check the positioning. Start engraving the circle by tilting the saw onto the front wheels. Switch the saw on and lower the blade to start the cut. Apply downward pressure and push the cart; since the cart is anchored to the pivot point, the diamond blade will move in a circular direction. Continue engraving the circle until the blade reaches the starting point.
Cut an arc by setting up the circle cutting attachment the same way as described for cutting circles. Tilt the saw cart and position the blade fairly close to the starting point of the arc. Turn the saw on and carefully lower the blade until it reaches its full cutting depth. Turn the saw off and check the rear position of the cut. Move the cart backward slightly and repeat until the back of the cut meets the starting point of the arc. Continue cutting the arc by pushing the saw cart forward until the front of the blade reaches the end point of the arc.
Install omnidirectional wheels on the cart before performing cuts on a freehand design such as the body of a leaping dolphin or the irregular outline of a slate tiled floor.