From top to bottom: The first sector I made to demonstrate whole-number divisions; my three-scale paper version; a solid wood and brass sector by burn-Heart
I first stumbled on the sector as a layout tool through an article by Tom Casper in Woodwork magazine that appeared in the late 90’s. My curiosity engaged, I went through all the woodworking books in my considerable collection and couldn’t find a single reference. It turned out that the sector is essentially extinct. But as Tom pointed out, it was–and is–incredibly useful. The sector could effortlessly divide–with no measuring and therefore no math (fractional, decimal or otherwise involved)–a certain space up into whole number segments. When I presented the sector in my book “Measure Twice, Cut Once”, I showed how to locate drawer pulls two-fifths of the way in from either end of a drawer face.
I left it at that until just a few years ago when, on the recommendation of Joe Youcha (www.buildingtoteach.com), I got a copy of The Victorian Cabinetmaker’s Assistant published in the mid 1800’s. Here I learned that not only could the “Line of Lines” provide multiplication and division solutions along line lengths but it could also lay out (or find) whole number proportional relationships.
At this point having become rather obsessed with this tool, I sought out even earlier manuscripts from the 1700’s that described further workings of the sector. When I finally understood that the geometry of the sector allowed it to solve for unknowns among all sorts of ratios, I added another scale to a paper version that could provide solutions for the diameter, radius or circumference of a circle (i.e. the “Line of Circles”). The realization that the geometric truth underlying the six-sided figure (the hexagon) could produce another scale to provide the facet length of other polygons was exciting enough to keep me up half the night–and in the morning I added the “Line of Polygons” to the paper sector.
You can download a free template of this sector over in the shop section of this website–and you can also download a not-as-free, forty-page pamphlet that tells you how to use it. But you still can’t buy a “real” sector at Home Depot or anywhere else since they stopped making them (as far as I can tell) more than 100 years ago. Until now!
Due to the enormous efforts and talents of Brendan Gaffney of www.burn-heart.com), we now have a limited number of his solid maple-and-brass hinged sectors in stock. Read more about them over on our shop page where there is also a link to a video on working with it. This batch is the last of his first run so this is your last chance to get your hands on a first edition!