[PSUBS-MAILIST] calculation

[Alec Smyth via Personal_Submersibles]

Does the window seat have some sort of inside diameter edge? I would think
if it does not, then its pretty much guaranteed to slip with or without
grease - with grease being the quieter less-terrifying option.

Best,

Alec

On Mon, Jul 6, 2015 at 6:50 PM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

>
> Sean,
> Thank you for the input, I think I will just use weights like Alan says.
> I am making a fixture to simulate the EPDM gasket compressed under my
> dome.  I want to test it with grease and without.  I will squeeze the
> gasket in the fixture then push the top plate sideways with a pusher bolt
> to see if the gasket allows movement.  I want to make sure my dome can
> expand and contract at depth.
> Hank
> --------------------------------------------
> On Mon, 7/6/15, Sean T. Stevenson via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>  Subject: Re: [PSUBS-MAILIST] calculation
>  To: "Personal Submersibles General Discussion" <
> personal_submersibles at psubs.org>
>  Received: Monday, July 6, 2015, 9:08 AM
>
>  Hank - the force developed is dependent on the
>  stiffness of both the bolt material and of the specimen
>  you're pushing on.  You can't necessarily equate
>  this directly to torque because of friction in the bolt
>  threads and at the bolt end contact, and of course the
>  elasticity of the bolt itself. You can only estimate it.
>  There are many online tools for calculating the developed
>  tensile force in a bolted connection, for example, but these
>  consider only the bolt as the deformable element, and
>  require an accurate estimate of coefficients of friction,
>  and this will change with lubrication. As you complicate the
>  system, it becomes more geometry dependent.
>  A 1" - 8 UNC 2A thread is 8 threads per
>  inch, so a set number of turns will give you the approximate
>  axial displacement (0.125" per revolution - approximate
>  because the bolt will change length under load). If you
>  assume a rigid fixture, then your strain is equal to the
>  overall change in length (calculated from # of bolt turns),
>  divided by the gauge length (distance over which the length
>  change occurs, which would be the length of your specimen
>  measured between the rigid fixture and the end of your jack
>  bolt). Compressive or tensile load is then calculated based
>  on the modulus of elasticity of the specimen.
>  Alternatively, you can measure the load (make the bolt or
>  fixture into a load cell or strain gauge the specimen) and
>  calculate the material properties.
>  Load, axial displacement, modulus. You need any
>  two to calculate the third.
>  What are you making / testing?
>  Sean
>
>
>
>
>  On July 6, 2015 6:26:49 AM
>  MDT, hank pronk via Personal_Submersibles
>  <personal_submersibles at psubs.org> wrote:
>  Hi all,
>  I
>  need help, can anyone tell me how to calculate how much
>  force a bolt can push or pull using a torque wrench to turn
>  the bolt. So how many foot pounds of torque does it take to
>  rotate a bolt to  create 250 lbs push with a 1 in coarse
>  thread bolt.  I need to make a test fixture.
>  Hank
>
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