Both porcelain and ceramic tiles are made from feldspar and clay materials, but porcelain tiles are fired in the kiln at a higher temperature. The kiln process vitrifies the porcelain tiles, making them very hard and much more difficult to cut than ceramic tiles. To make precise square and semicircle cut-outs in your porcelain tiles, you will need an angle grinder with a dry-cut diamond wheel .
Mark the outline for the square cut-out on both the front and the back of the porcelain tile using a wax pencil, a ruler and asquare template. Clamp the tile to your workbench.
Score the front of the outline of a square cut-out about 1/8 inch deep with your angle grinder diamond blade. Turn the porcelain tile over and make a plunge cut through the marked lines on the back of the tile.
Make a cut at the first corner of the square cut-out and continue to the next corner, going slightly past the line. Continue this process around the scored square to complete your cut-out. Firmly push out the cut-out from your porcelain tile.
Mark the outline for the semicircle cut-out, from the edge of the tile, on both the front and the back of the porcelain tile, using a wax pencil, a ruler and your semicircle template. Clamp the tile to your workbench.
Score the front of the semicircle outline with your angle grinder. Beginning at the edge of the tile, make a vertical cut 1 inch in from the right side of the semicircle. Stop at the top of the curve 1/2 inch from the centre. Repeat this procedure on the left side of the semicircle.
Make shallow horizontal plunge cuts connecting the two vertical cuts you made to slowly remove the excess tile. Continue this procedure until all the excess tile inside the vertical cuts has been removed. Make small radial cuts around the edge of the semicircle to clean up the jagged edges of the curve. Grind slowly around the curve with your grinder to smooth the edges of the semicircle.
You can clean up any rough edges in cut-outs with a tile nipper.