Suspension spring material??

Discussion in 'Tower, Monumental & Street Clocks' started by tsmith, Aug 9, 2009.

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  1. tsmith

    tsmith Registered User

    Nov 5, 2008
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    Cypress, TX
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    A recent thread about suspension material for tower clocks motivated me to research it a bit.

    I dug out a 1987 article on suspension design, pros and cons of the different types, that also addresses the design of the typical spring suspension. One thing that got my attention was the use of .004" x 0.5" wide and 0.75" long on 14-16 lb pendulums and the author mentioned using up to .008" with some loss of effiency. That seems awfully thick for a bob that weighs less than 20 lbs.

    Has anyone tried to used feeler gauge material such as Starrett? It comes in a bunch of thicknesses, 12" long x 1/2", appears to be pretty hard and is readily available at most tool suppliers and some auto parts houses. Metal fatigue might be a issue here but I've never tried it.

    Tom
     
  2. gvasale

    gvasale Registered User
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    Mar 30, 2005
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    fortunately, I've needed to replace suspension springs only twice. One was easy, but not cheap, the other wasn't as expensive, but not as easy.

    A coil of correctly size material did the first one, then cut to length.

    The second, proper in thickness, had to be sheared for width, then cut to length. Shearing eliminated any irregularities, arriving at proper width and no multiple sharpies. Left a small burr, easily stoned away.

    Have not tried using feeler stock, or even shim stock to do the same job.
     
  3. Jim DuBois

    Jim DuBois Registered User
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    Jun 14, 2008
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    I have used "feeler guage" stock from Starrett for many years on many clocks with success. From French clocks to tower clocks. Different thicknesses and widths for different clocks. My little Howard 00 has 2 strips of .008"x5/16" width and seems to work well enough. I usually try to dublicate what ever was there originally, deminsionally speaking at least.

    The feeler guage material can be cut with tin snips and then the edges can be cleaned up with a stone or Dremel tool and the like. I have also sliced thicker material with a very thin diamond saw. For a special torsion spring suspension .0015"x.050"x14" I used a papercutter.....not necessarily good use of a paper cutter but everything else I tried was less successful....
     

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