Plants convert excess glucose into starch for storage. The image shows starch grains (lightly stained with iodine) in the cells of the white potato. Rice, wheat, and corn (maize) are also major sources of starch in the human diet.
A counterbore (symbol: â´) is a cylindrical flat-bottomed hole that enlarges another coaxial hole, or the tool used to create that feature. A counterbore hole is typically used when a fastener, such as a socket head cap screw, is required to sit flush with or below the level of a workpiece's surface.Whereas a counterbore is a flat-bottomed enlargement of a smaller coaxial hole, a countersink is a conical enlargement of such. counterbore hole is usually used when the head of a fastener, such as a hex head or socket head capscrew, is required to be flush with or below the level of a workpiece's surface.
The counterbore tool is typically a specialized drill bit that creates the hole for the body of the fastener and the larger sized cavity for its head, both at the same time. Usually, the fastener chosen is a flat-bottomed screw such as a round head or a pan head screw.sually, a socket wrench is used for the purpose, which means enough space must be available around the screw head to insert the socket wrench and allow it to grip the head of the fastener. For this, the counterbore cavity is drilled to a diameter larger than that necessary to accommodate the socket wrench.