1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Threaded screws

  1. Oct 19, 2005 #1
    Im having problems solving this problem.

    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

    The image is here
    Last edited: Oct 19, 2005
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you help with the solution or looking for help too?
Draft saved Draft deleted