Path: ...!Xl.tags.giganews.com!local-1.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail 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> From: Phil Hobbs Message-ID: Date: Fri, 26 Apr 2024 19:54:28 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Lines: 55 X-Trace: sv3-srAJR3GAJbJgYStGCc/5ne/ao6eDuIuk03wWVlNNsmnnF+KRkg7HQUcb/9RhWvnDMXKMM2RLxuqEetg!vrzdYgq3CBm6jbc4oY7h/+ySnvBJQGXmQZfpulXT54pPuAG8A7HG9mMJaoqr1BHNhBrhivaE4cGL!qb7mxNE5LV9UD/WfmLuPDSyA X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 3055 On 2024-04-26 15:30, Joe Gwinn wrote: > On Fri, 26 Apr 2024 14:46:52 -0400, bitrex wrote: > >> I have one of these inexpensive Ikea bookshelves for storing some of my >> electronics books: >> >> >> >> 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