Re: OT: central limit theorem

On 27/04/2024 4:46 am, bitrex 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.
 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.

Or put on a backing sheet and knock some nails through the backing sheet into the shelves. It isn't elegant. I've built bookcases where I've rebated the frame so that the backing sheet didn't show when viewed from the side, but my wife thought that this was more trouble than it was worth.
We owned a lot of books and the default bookshelf was mounted on brackets screwed into plugs let into the wall. I'd had a masonry drill even before we got married.
My great-grandfather would have been scandalised. I've now got the glass-fronted bookcase he built to complete his joinery apprenticeship some 150 years ago, and it is much more elegant piece of work.
--
Bill Sloman, Sydney