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A C-Clamp is used to clamp a piece of wood to a workbench. its double square threads have a mean diameter of 3/8 in. and a pitch of 1/10in. The static friction coefficient between the threads is 0.25. If a torque of 30lb/in isapplied in thightening the clamp, determine (a) the compressive force on the wood and (b) the torque required to loosen.

I need help getting started. I think this is the order and formulas I have to use.

1)Lead angle= tan-1(np/2*3.14*R)

which ends up being tan-1 ( n*.375/2*3.14*.375)

I know n is the number of threads but i dont know how to calculate it.

2)Loading Torque

M=Wrtan(static friction angle - lead angle)

How do you calculate the static friction angle?

3)Mechanical advantage M.A=W/F=....

4)Compressive force? how do i calculate this?

Sorry for the long post. Thanks in advance

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# Homework Help: Threaded screws

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