My furniture designs often slide, fold, or translate in some fashion. This often means that the location of holes and the length between them is carefully calculated. In fact, I find a good calculator to be one of my most used tools.
The problem with specific dimensions and most calculators, though, is that they don’t know carpenter scale (1″,1/2″, 1/4″, 1/8″, 1/16″,1/32″). My latest project, for example, uses a swinging link arm to control how far a drawer will pull out of a small table. It slides in a slot on one end, and pivots from the other. I needed very precise measuring for the slot in the back panel of the drawer, the location of two holes on the link, and the location to mount the link to the table underside.
It was very easy to know what all the dimensions needed to be. The link need to be 8.543″ between hole centers. Normally, I’d convert to 32nds by removing the “8”, and multiplying the “.543” by 32. In this case, 8 and 17.376/32nds isn’t an easy dimension to find on my tape measure. Being off by a 64th is something I wanted to avoid here.
Then I remembered my old engineering scale. You can find them at any college bookstore with a supplies department. I’ve had mine since taking an engineering structures course 20 years ago. Instead of using 8th and 16ths, this scale breaks an inch into 10 or 20 or 30 or 40 or 50 or 60 increments. The “20” scale, for example, would have a mark representing every .05 of an inch. The “50” scale marks an inch into 50 .02″ segments. It’s easy to take my fraction (.543) and divide it by .02 to know how many units on the 50 scale to count off.
Using my engineering scale I was able to very precisely (within .003″) lay out and create my control link. It’s now in place, and actually surprises me at how well it works.
My point? If you’ve ever need to break an inch into something other than 16ths, consider getting an engineering scale.