The portable circular saw, also known as an electric hand saw, utility saw, cut-off saw or builder’s saw, is a power tool used to cut lumber and boards to the right size.
It is mostly used for woodworking, but other materials can be cut when it is fitted with specialized blades; metal cutting blades, for example, are available for cutting lead, copper, sheet metal, brass and aluminum. Most circular saws take blades with a 5 inch or 7 ½ inch diameter, with larger blade saws for industrial use also being manufactured.
A stationary upper blade guard as well as a pivoting lower blade guard is included on all saws for safety. As the lower guard is spring-loaded, when the saw passes through the work, the guard retracts and then automatically returns when the blade clears the workpiece. The upper blade guard protects the user from debris as well as from the blade.
There are many types of blades to choose from, and it is important to select the proper blade for the particular job and material. Using the wrong blade can damage the saw by straining it’s motor or putting undue wear on the blade, as well as ruin the workpiece.
Blades should be sharpened periodically by a professional sharpener, as a dull blade can also ruin your work and be dangerous. Note: Always disconnect the power cord from the electrical outlet before changing a blade.
Some of the common circular saw blade types include-
-Cross Cut Blade: for cutting wood perpendicular to the grain
-Rip Blade: for cutting wood along the grain
-Combination Blade: for cutting wood at any orientation to the grain, also for composite type engineered woods
-Abrasive Disk: flexible, shatterproof disks for cutting non-wood materials. Aluminum oxide disks cut thin gauge ferrous metals, while a silicon carbide flexible disk cuts slate and marble.
-Carbide Tipped Blade: For durability, hardened saw teeth keep sharp longer.
-Planer Blade: cuts with a fine finish on wood
-Flooring Blade: used for cutting old wood where there is a risk of cutting through nails, or composite wood materials with high glue content
-Friction Blade: used for cutting thin gauge sheet metal or corrugated iron
Most circular saws include a rip fence attachment on the base plate. This is useful as a guide when doing repeated rips cuts, letting you make fat and accurate cuts without making layout markups on the work. The fence is adjustable and can be used on either side of the blade, usually whichever side is nearest the edge of the work.
In order to set the fence up for a rip cut, measuring from the inside face of the fence to the blade will give you the width of the cut. Position the fence at the edge of the work and tighten the adjustment knob. In lieu of a fence for a guide, you can clamp a strip of wood parallel to the cut line onto the work piece. Running the heels of the saw along this line while making the cut will ensure a straight line.
Setting Cut Depth
Although making cuts with a circular saw is convenient and quick, it is easy to forget to set the proper depth. In this case you will probably have some splintering in your workpiece at the cut line. For many jobs, a little bit of splintering will not make much of a difference, but for high quality work, you should take the time to set the cut depth.
For the minimum amount of splintering, the optimal cut depth is when the blade is adjusted to project 1/8 inch from the underside surface of the work. To do this, put the lower guard in the open position and place the saw’s sole plate on the workpiece, with the blade against the side edge.
Then release the knob that adjusts the depth and swing the saw body down or up while maintaining the sole plate flush with the work, in order to get the blade projecting the proper amount from the work’s lower surface. Then make sure you tighten the depth adjustment knob again.
To make partial depth cuts, the procedure for adjusting is much the same. Instead of adjusting so that the blade projects below the work’s bottom, simply mark the side edge with the depth of the cut, and then, laying the blade against the edge, position the depth such that the lowest point of a blade tooth just touches the mark line.
Re-tighten the adjustment knob and proceed to make the cut. You can use this partial cut method as a way to make a dado or groove in a work piece, by making multiple cuts the width of the groove. Clear away any waste material by hand using a wood chisel.
Photo by John Loo, Creative Commons Attribution License