Many kitchens contain arcs circle, large radius etc. The layout of these unusual geometric shapes pose problems for many fabricators. The following is a basic procedure that I use for making these cuts.

Making a template

There are many ways to lay out an arc. To lay out an arc mathematically, we use a coordinate system with the chord along the x-axis. R is the radius. The perpendicular distance from the center of the chord to the arc is H. The center of the circle is a (0, h-r). Here is the equation: X^2 + (y-(h-r))^2 =r^2

Next we can solve for y in terms of x as follows: y =sqrt(r^2 – x^2) – r +  h

The easiest way to lay out any arch that doesn’t require a Ph.D. in math is to use a template. If you take a stip of laun and turn it on end, you can simply bend it to the desired arc or radius. Next, attach several support strips to hold it in place.

Cutting the arc

Once you have the template made, you are now ready to cut the arc. Here is a basic procedure:

1. Lay out the arc or circle on the stone by tracing the template with a white out marker.
2. Set up a small hand saw with a  5 in. contour blade. Make sure the blade is set up so that the contour (convex side) is facing in toward the motor of the saw. For proper mounting instructions see the instructions equipped with the saw.
3. Connect water to the saw and plug the cord into a GFCI equipped outlet. Check the GFC button on the cord of the saw to make sure it is working correctly by pressing the test button. The GFCI device should make a low popping sound when the test button is depressed. If the popping noise occurs, then the GFCI is working correctly. Press the red reset button. Caution: You can only test the GFCI when it is plugged into a live outlet. It will not test properly unless plugged in.
4. Adjust the depth of the blade so that it is cutting all the way through the thickness of the stone.
5. To start cutting the arc or circle, take the saw and position it on the outside of the cutline -- about 1/8 of an inch to the outside. Hold the saw so the blade is not touching the top. Turn the water on and start the saw by depressing the start button. Slowing plunge the blade into the stone, being careful that it does not kick back. Once the saw blade is all the way though the stone, slow push forward following the marked line but staying about 1/8 of inch outside the line. When cutting a tight radius, make sure the back of the blade does not hit the line as you make the turn. In other words, watch both the front and back of the blade as you are cutting.
6. As you reach the end of your cut make sure the piece is supported on both sides so it does not snap off as you reach the end of the cut.
7. To clean the cut treat it like you would an undermount sink cutout. Clean up with a zero tolerance bit and finish as you would a normal edge.