Lindsey Weiss Table Saw August 01st, 2018 - 23:50:50
In the modern table saw, regardless of type, the depth of a cut is changed by adjusting the distance that the blade sticks out above the table surface. The more the blade protrudes from the table, the deeper the cut that is made in the material will be. Conversely, the less a blade protrudes from the table, the more shallow the cut that is made in the material being cut, will be.
The trunnion is the mechanism inside the cabinet which is responsible for both raising and lowering the blade and tilting the blade for bevel cuts. It is controlled from the outside of the saw by two separate wheels or cranks: one for raising and lowering the blade (usually found on the front of the cabinet) and the other for tilting the blade (either left or right, depending on the saw) which is usually, but not always, located on the side of the cabinet.
Beginning at the bottom, the table saw base houses the working parts of the saw, including the trunnions, the arbor assembly, the sector gears, and sometimes the motor. On some saws, the base is a "cabinet" type, meaning that a fully enclosed base extends all the way to the floor. Other saws have an open base, meaning that the base consists of a metal box that surrounds the internal working parts of the saw on four sides, but not the bottom. Open base saws have legs that extend downward from the bottom of the base to the floor.
The quality of the table saw surface (or "bed") is extremely important to the overall performance of the machine. The table surface needs to be reliably flat and rigid to properly support the workpiece during a cut. As one of the most massive parts of the saw, the table surface also plays a major role in absorbing vibration. Because of the need for mass, rigidity and flatness, cast iron is the material of choice for the top of a table saw. On a quality saw, the table is made using a hefty quantity of cast iron and state-of-the-art foundry methods. The end result of the casting process is then precision ground to flatness in the .0005'' tolerance range.
The trunnion determines the accuracy of your cuts so you want to be sure that it is well built and accurately machined. The saw blade must always be exactly where you need it to be. Furthermore, the trunnion must be easy to operate. It should not require Superman to raise or tilt the blade. As time goes on, you may find that it is harder to turn the wheels or cranks that operate the trunnion. This is usually because of sawdust contamination of the gears and/or lack of lubrication. Some better saws have ways of eliminating sawdust from the cabinet into an external dust port before it can get into the gears. Other saws come with self-cleaning gear teeth.