The two general types of reciprocating saw blades are toothed blades and abrasive blades. Whereas toothed blades cut through soft materials, such as wood and plastic, abrasive blades grind through tough materials, such as concrete and stone. Finding the most suitable blade for a concrete project includes comparing blades' attributes, such as size and type of abrasive coating, to the requirements of the project.
Abrasive Coatings
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The abrasive coatings that allow a reciprocal saw to grind through concrete consist of mineral-grit and there are two basic types of mineral-grit blade coatings: carbide and diamond. Aside from its reputation for beauty, the diamond is one of the hardest substances on the planet. Because of their exceptional hardness, diamond coated reciprocal saw blades create smooth cuts through hard materials, such as concrete and stone.
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Regarding tools, the term carbide actually refers to a compound called "tungsten carbide." Although tungsten carbide blade coatings are generally less hard and durable than diamond coatings, they are several times more robust than steel. Reciprocating saw blade manufacturers label both diamond and carbide coated blades as "concrete cutting blades." Diamond blades are typically more expensive than carbide blades.
Blade Size
Concrete cutting reciprocal saw blades appear in various widths, lengths and thicknesses. Choosing the right size blade for a particular concrete projects requires the builder to determine the desired depth and shape of the cut. If a blade must slice through an entire concrete component, such as a block or slab, the blade's length should exceed the concrete component's length by at least 2 inches to allow the tool to freely reciprocate on both sides of the work area. Additionally, long blades are often more flexible than short blades and therefore more suitable for creating curved cuts.
Safety
Cutting concrete with a reciprocating saw begins with safety gear. Cutting concrete creates dust and sends sharp shards of material flying toward the tool operator. Because concrete dust can cause respiratory discomfort or damage, reciprocal saw operators must wear face masks or respirators. Gloves, goggles, ear mufffs or ear plugs protect the operator from potential harm.
Alternative Tools
Although a reciprocal saw's long, thin blade is often the best tool for the job, many tools offer easy methods of cutting concrete. The most common, alternative concrete-cutting tool is the angle grinder. Angle grinders spin abrasive, circular blades and, although they generally don't cut as deep as reciprocal saw blades, they create smoother cuts with less resistance.
Alternatively, hammer drills equipped with masonry drill bits quickly and easily cut through concrete. Even if a drill bit cannot complete the entire project, it can create an access hole for reciprocal saw blades.