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Cinder blocks are a common building material. Made from cast concrete, cinder blocks are hard and durable. The same qualities that make cinder blocks good for construction also make them difficult to cut. One of the easiest ways to cut a cinder block is with a reciprocating saw that has a diamond-coated blade. The reciprocating saw uses an electrical motor to move the saw blade back and forth rapidly, mimicking the motion of a conventional handsaw without as much effort.
Unplug the reciprocating saw, or lock the trigger to prevent accidental activation. Open the blade lock according to the manufacturer's instructions. Insert the tabbed end of the diamond-coated blade into the blade slot. Close the blade lock.
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Measure and mark a line where you are going to cut the cinder block. Hold the cinder block securely with a clamp.
Plug in the reciprocating saw and unlock the trigger.
Place the shoe of the reciprocating saw against the cinder block with the blade directly above the cut-line. Squeeze the trigger gently until the blade begins to move.
Lower the end of the blade to the cut-line, keeping the shoe of the saw against the cinder block. Increase pressure on the trigger to speed up the blade once the blade begins cutting.
Maintain steady pressure on the back of the saw, allowing the blade to do the work. Keep the shoe against the block to help prevent kickback. Continue working the blade through the cinder block until the cut is complete.
When making multiple cuts, or when cutting through thick material, stop frequently and allow the blade and saw to cool.
Never use water to aid with cutting when using an electrical reciprocating saw.