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Choosing the best shape for the screw depends upon the purpose it must serve. Here are the most common shape and sizes of screws:
Flat head - This screw is the most popular and can be counter-sunk, meaning, screwed in until its head is level with or somewhat below the surface of the stock.
Oval head - This screw type can be countersunk and commonly sunk to the rim, it usually bulges out a bit.
Round head - The screw head has a slightly decorative function for it bulges out totally.
Fillister head - The head is shaped like three checkers atop each other to be easily countersunk.
Bung head- The little head, not much wider than the shank, can be comfortably countersunk.
Binding head - This screw type has slightly tapered sides and round top.
Lentil head -This screw is shaped like a little M & M candy.
Headless- The slot of this screw is recessed in the stem.
Truss head, or stove head - The head of this screw is wide and thin.
Pan head - As the name implies, the head is formed like an inverted frypan, narrower on the top, flat on top and bottom.
Drive - A steel, spiral knurl (an elevated twirl) is tempered to make the screw easily driven into soft metal.
Dovel -It is a wood screw with threads on both ends.
Winged - The screw head is shaped like a wing for it to be turned using the fingers.
Hanger bolt -This is basically a wood screw on one end and a machine bolt on the other.
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