I plan to talk about glues and joinery at the repair class at Upholstery Fair 2010. Here is an interesting article on different types of joints and failures when tortured:
http://www.popularwoodworking.com/article/The_Anvil_Test/?print=1One of the first things I ever read in woodworking is why dowels make bad joints. Yet we see them all the time in dining chairs.
Also, if you read the article carefully, there is a distinction between a joint that fails gradually (and is repairable) and one that fails catastrophically and may not be repairable. In pieces that we sit on, it means getting a wobbly feeling vs. falling to the floor.
When I was designing and building products (of a different sort), we always kept in mind the ability to repair or do maintenance on something. I am reminded of some of the 1960s cars that were designed so that you had to remove the whole engine to replace the sparkplug, or remove significant body work to replace a headlight. And, or course, early iPods that didn't have a replaceable battery. When it failed to take a charge, time for a new iPod. [but, I digress]
Woodworking and joinery -- the orthopedics of upholstery ? Come on, the first one is free.
Bwaaa-haaaa-haaa 
