[PSUBS-MAILIST] calculation

[Alec Smyth via Personal_Submersibles]

A flat ring cut from thin plastic and lubricated with vacuum grease on both
sides. I'm glad to say it doesn't make any sound at all.

Alec

On Mon, Jul 6, 2015 at 9:32 PM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

>
> Alec,
> What is under your dome.
> Hank--------------------------------------------
> On Mon, 7/6/15, Alec Smyth 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, 8:31 PM
>
>  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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