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NNTP-Posting-Date: Fri, 26 Apr 2024 23:54:28 +0000
Subject: Re: OT: central limit theorem
Newsgroups: sci.electronics.design
References: <662bf69c$0$8484$882e4bbb@reader.netnews.com>
 <i00o2jtj8peuu9su6s18fdcss1t24l38bd@4ax.com>
From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Message-ID: <c1a55bb4-8d0b-a713-85a4-1d61ff2c27e0@electrooptical.net>
Date: Fri, 26 Apr 2024 19:54:28 -0400
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On 2024-04-26 15:30, Joe Gwinn wrote:
> On Fri, 26 Apr 2024 14:46:52 -0400, bitrex <user@example.net> wrote:
> 
>> I have one of these inexpensive Ikea bookshelves for storing some of my
>> electronics books:
>>
>> <https://www.ikea.com/us/en/p/laiva-bookcase-black-brown-40178591/>
>>
>> I noticed the center shelf was starting to sag a few degrees. :( The
>> assembly manual specifies a weight limit of 33 lbs evenly distributed
>> which seemed like an oddly specific number. So I weighed the books on
>> the shelves, which aren't particularly well organized other than to
>> fully fill the available space widthwise on each shelf.
>>
>> A random assortment of hardbacks and paperbacks, some are tall and
>> skinny, some are short and fat. And each shelf was clocking in at 33 lbs
>> +/- 2 lbs.
> 
> Ikea shelves are made of veneered particle board, and can creep under
> steady load.  Is it possible to flip the shelf planks upside down, so
> they start to creep back towards straight?
> 
> 
>> So I guess a heuristic for filling these shelves is just fill 'em up
>> then remove the heaviest book, and de-rate the center shelf by maybe 5-
>> 10 lbs because it's unsupported by a backing.
> 
> If the shelf plank material is creeping, this won't work.
> 
> Joe Gwinn
> 

The OP might want to upgrade to Ivar shelves. I’ve got probably a dozen 
sections, 7 feet tall, and Ikea still sells them, I think.

Inexpensive, solid wood, good looking, super strong, and last forever.

Otherwise they stink.

Cheers

Phil Hobbs



-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com