Originally Posted by
Stanley Covington
If I need to layout a tenon or mortise, I can measure the width, split the difference with a divider, and layout centered on a line marked on tenon or mortise or both. Quicker and more accurate than fiddling with marking gauges.
When laying out mortises/tenons on stile and rails, a divider set to the desired height of mortise/tenon will ensure every mortise is laid out exactly. When doing multiple doors, windows, or shoji, the divider can be used to mark the story sticks (vertical and horizontal) used to layout each rail/stile.
When making shoji with complicated kumiko, the precision and repeatability of a lockable divider with a fine screw adjustment is essential. Simple can't be done with a measuring tape.
A divider used properly makes it easy to check for and eliminate accumulated errors. Nothing can do this as well as a good locking divider with a fine screw adjustment.
When laying out legs and backs for chairs, a divider makes it easy to triangulate and mark centers quickly and precisely from a centerline on the seat's center.
When doing trim work, or fitting floor boards to walls or around columns, a divider with a pencil attached (like the Starrett) can be used to scribe cut lines, transfer distances, and triangulate transition points.
And of course, nothing beats a divider for precisely and quickly dividing a line/distance into equal parts.
A divider beats every other tool at laying out angles, halving angles, and locating points on a circle.
There are many other operations that a divider does best. I usually have three dividers, all with sharp points and fine screw adjustment, on my workbench whenever doing layout.
There are a good reasons why the divider, along with the square and plumb, is the most ancient of mankind's tool.
Stan