A few naughty readers have been attempting to build collapsible tables and bookcases similar to ones I’ve been constructing for “Campaign Furniture” and have run into some trouble.
Instead of being a wiener-kabob and saying “wait for the book,” here is some basic but critical information about mechanical furniture: In these simple constructions, the pivot points have to be equidistant.
What does that mean? Take a look at the quick-and-dirty sketch above. In these bookcases, the center pivot point is on the outside of the bookcase. The top pivot point it 7-1/4” above that — right below the top shelf. The lower pivot point is 7-1/4” below that right above the lower shelf.
If the upper and lower points are not equidistant from the center, the bookcase will not fold flat. Also good to know: If the distance between the lower and upper pivot points is greater than the length of one of the shelves, the bookcase will not fully collapse. The two center pivot points will run into one another.
I am almost finished building this bookcase and will post a movie later this week.
— Christopher Schwarz