Formica is thin and flexible, which can make it difficult to cut. Sheets of Formica should be cut on a table saw with a combination blade. This ensures clean edges and square cuts. It's very simple--all you need to do is clamp two small blocks to the fence of the saw to hold down the Formica while you push it through the blade.
Take off the old blade and put on a combination blade. Slide the fence over until it touches the blade. Clamp one block to the fence in front of the blade, and one block in back of the blade. Allow about 3/16 inch underneath for the Formica to slide under.
Measure and set the fence where you want your first cut.
Raise the blade so that about 1/2 inch protrudes above the table. Turn on the saw. Put on your rubber gloves. Spread your arms out to about 48 inches, pick up the Formica and set it on the saw behind the blade. Slide it over to the fence and allow the edge of it to go under the block behind the blade.
Move your body into position directly behind the blade. Your arms should be holding the Formica on both sides of the blade. Push the Formica into the blade slowly. If the Formica begins to chatter as the blade cuts, slow down. Keep pushing until the Formica slips under the second block.
Continue pushing the Formica all the way across the blade. When you get to within 6 inches of cutting through, place your palms flat against the Formica on either side of the blade. The gloves will grip the Formica. Continue pushing the Formica through, palms down.
If you have an assistant available, its helpful to have him hold the far end of the sheet when cutting.
Always wear safety glasses when cutting Formica.