Screw

The difference lies in how the thread pitch is measured. Metric bolts define their pitch by the distance between each thread. There are still fine and coarse threads but this time the bolt dimension may be 6mm x 40mm x 1.0 or 1.25 in the case of a fine thread. A coarse threaded bolt of a similar size will have the dimensions of 6mm x 40mm x 1.75 or 2.0. ................
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