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# What is the difference between v thread and square thread ?

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Square threads: The sides of the flanks of square threads are normal to the axis and hence parallel to each other. The pitch of the threads is often taken as twice that of B.S.W. threads of the same diameter. These are used for power transmission.

V threads: British Standard Whitworth (B.S.W.) thread: It is a symmetrical ‘V’–thread in which the angle between flanks is 55°. These threads are generally used on bolts, nuts and studs et

Isn't the answer obvious to anyone with eyes? Why do we have questions like this? What is the point?

DrD

Square threads are not easy to produce and are hardly ever used as a single thread. They are used in items like mechanical vice and most often have double or triple threads. You can apply lots of linear force in their application and they will not slip or break easily. To assist in this arrangement the vice will have a Bronze sister screw which help to reduce friction and are the fuse in case you apply to much pressure. There is also the dynamic of range accomplished. The square thread is usually much coarser than a V-Tread and can screw quicker in meters per minute because of the double or triple application. It is not easy to line up and screw this thread in seconds, so it will not do for a screw application where you need speed in the assembly. You will never spend the sort of money it costs to produce a square thread, on a hydraulic hose fitting. And the assembly time would be prohibitive. Size is another factor. Square thread go as small as perhaps one inch/25.4mm diameter where V-Threads can go to perhaps two millimeters. Apart from a table vice there is not much use for this thread.

In square thread, the torque is converted into axial force inline with the rod axis. Hence whole force is utilized.

While in V thread the torque is converted into axial and radial force, just the axial component is useful.

Due to that, square thread is better in power transmition, but it is more difficult to manufacture because it needs a flat cutting tool. V thread is easier to manufacture but generally used for fastening and tighting rather than power transmition.

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