Precast concrete blocks, also known as cinder blocks, are a useful, simple-to-use building material. These blocks are readily available in a range of standard sizes and work well for building foundations, walls and other sturdy structures. Most concrete blocks can be used as-is, but some applications require cutting them to size or angling them for a mitered joint. Several tools work well for this job.
Masonry saws resemble circular saws but are much larger, heavier and more powerful. These saws work more like grinders than conventional saws, wearing away at the surface of the block. They work both to cut block before it has been laid and to cut through cinder block walls to create spaces for doors and windows. Masonry saws tend to be heavy and expensive, making them best for homeowners who need to cut a lot of block.
This hand tool is also called a mason's chisel. It's a relatively wide, strong chisel with a shorter handle than a wood chisel. The blade and handle are cast in one piece to help the tool withstand the force of mallet blows. Most masonry chisels have a duller blade than chisels meant for wood since they're used primarily to split and gouge the concrete. "Building with Masonry" recommends a 2 1/4-inch wide chisel for basic cutting purposes.
Reciprocating saws hold a straight blade by one end and move it back and forth to cut the material, mimicking the action of a conventional hand saw. When fitted with a carbide grit blade, reciprocating saws work well to cut and shape concrete block. The saws can be difficult to control but offer a wider range of cuts than many masonry and circular saws. Use relatively smooth grits to cut neatly but slowly, and use coarser grits for a fast, but less tidy, cut.
Circular saws are handheld tools that hold a rotating circular blade. They're commonly used to cut lengths of lumber into shorter pieces but also work on masonry when fitted with the correct blade. Circular saws are best used for small cuts since their blade depth only allows them to cut a certain amount of material at a time – usually about half the width of the blade. Work slowly to prevent the saw's motor from overheating.