[PSUBS-MAILIST] calculation
Alec Smyth via Personal_Submersibles
personal_submersibles at psubs.org
Mon Jul 6 22:48:14 EDT 2015
Unfortunately I don't know the hardness, but it would be super high because
the material is polycarbonate sheet. In my case the ring does not serve as
a gasket. The dome is sealed by an O ring. The square edge of the acrylic
is chamfered to take the O ring, and the flat plastic ring is just a spacer
to get the O ring to touch both the chamfered acrylic and the window seat
to form the initial seal. I had to experiment with a few thicknesses until
I found one that made everything fit together just right. It was something
like 1/16".
Best,
Alec
On Mon, Jul 6, 2015 at 9:58 PM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:
>
> Alec, do you know the hardness of the plastic ring. The Acrylics hand
> book recommends min duro 80.
> 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, 9:52 PM
>
> 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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