To cut concrete blocks, mark the cut all the way around with chalk, score the cut with a hammer and chisel, and then set the block on sturdy, level ground. Hold a chisel perpendicular to the block at the score mark, and sharply hit the chisel with a 6-pound sledgehammer.
- Mark the cut
Measure the location for the cut, and mark it with a piece of chalk against a straightedge. Mark the cut all the way around the block.
- Don safety equipment
Put on safety goggles, heavy-duty gloves and a dust mask to protect yourself while cutting the block.
- Score the cut
Hold a chisel perpendicular to the block at the chalk line. Gently strike the chisel with a hammer to a depth of about 1/8 inch. Move the chisel along the line until the entire cut mark is scored to a depth of 1/8 inch.
- Set up the cut
Place the block on the ground in a relatively level, sturdy position. Hold a cold chisel in the center of the scored line at the top of the block. Keep the chisel perpendicular to the block and lined up with the score mark.
- Strike the chisel
Hold a 6-pound sledgehammer near the head. Strike the chisel with a sharp blow. If the block does not cut all the way through, strike a second time.