Shelving recommendations?

Judi · Post by **Judi** » Thu Jan 01, 2009 2:44 am

Oh.

marydotson · Post by **marydotson** » Thu Jan 01, 2009 12:24 pm

Have courage...Just tell them that tank stands are always made of inert substances, hence they must meet the point of inertia!

chris_todd · Post by **chris_todd** » Thu Jan 01, 2009 4:07 pm

ingg wrote:moment of inertia.

Engineers. LOL

ingg · Post by **ingg** » Thu Jan 01, 2009 6:59 pm

It it just a phrase relative to strength of materials.

There are a couple of kinds of stresses you test for - everyone knows what Shear is, the ripping... the other type of stress is Moment, a rotational or twisting type of stress.

He was probably referring to the width of the shelving unit - moment increases a lot as distances increase - think of moment as, umm...

Swing a yo yo around. The force spinning it in the wide circle is moment. The longer the string, the more inertia the yo yo has - this is called the moment arm.

Longer the arm (wider the shelf), greater the force that must be resisted.

In the shelving unit's case, resisting moment means the shelves don't deflect and bend.

The relationship of the moment arm and the inertia created is not linear - which siomply means that double the length of the shelf means a lot mroe than double the amount of stress created, not a 1 to 1 relationship. So it is of concern when talking about shelving units, because we like big wide ones, which means big fat Moment forces...

Engineers and their Geekinese, lol.

maddog10 · Post by **maddog10** » Thu Jan 01, 2009 8:31 pm

So in layman terms, you need a strong shelf so it doesn't "fall down and go boom"

ingg · Post by **ingg** » Thu Jan 01, 2009 8:35 pm

Right - and long shelves need to be disproportionally stronger than a shorter shelf, because the relationship isnt a 1 to 1.

Twice the length, lots more than twice the stress.

chris_todd · Post by **chris_todd** » Thu Jan 01, 2009 11:39 pm

ingg wrote:It it just a phrase relative to strength of materials.

Engineers and their Geekinese, lol.

I hope you didn't think I was bustin on ya, Dave, cuz I wasn't. It's just that I knew what you were talking about (I'm not an engineer, but because of my interest in amateur telescope making, I have read enough about flexure, stress, and strain of common telescope making materials (wood, aluminum and glass) that I have come upon the terms and equations involved). I love it when geeks get geeky! After all, how often can I actually apply engineering principles learned from an interest in amateur astronomy to the hobby of aquatic plant growing! Boo-ya! (there has got to be a better geek battle cry, but maybe I'm too nerdy to know it)

magsdez · Post by **magsdez** » Fri Jan 02, 2009 12:34 am

ie yi ie!!

Here I thought I left Physics behind in college!!!!!!

Had to stretch the mind to follow what you were saying, Dave.

The one big thing I remember about phyics is that I didn't see a need for it in my degree track (pre-veterinarian). I figured, if a horse falls off of a 1000ft cliff, it doesn't matter how fast he hit the ground at or how far away from the base of the cliff he landed.......he's already dead! If he wasn't, well, my job would be to patch him up!

ingg · Post by **ingg** » Fri Jan 02, 2009 2:32 am

I hope you didn't think I was bustin on ya, Dave, cuz I wasn't.

No, I didn't - part of my regular job is to translate engeering speak to craftsmen and "laypeople"...

One of the ways I do that in seminars is to make light of it, call the big engineering terms we use as "Geekinese", and then explain what they are in terms folks can relate to. Gets folks relaxed, and learning instead of just boggling over terminology.

sherrymitchell · Post by **sherrymitchell** » Fri Jan 02, 2009 1:33 pm

maddog10 wrote:

Michael, Where did you get the power strip shown in this photo? That's very nice!!! Great stands, btw. You have a nice fish room.

Shelving recommendations?

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