Screw

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A screw is a sharp piece of metal similar to a nail. Unlike a nail, a screw has spiraling grooves down its spike. A screw is pressed down against wood and spun with a screwdriver so the wood goes into the grooves. This prevents the screw from falling out, as a nail could. Screws are basically divided in to Wood Screws , Machine Screws and Self tapping Screws.

Screw threads are measured either in mm or in numbers.

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