Chris Schwarz's Blog

Make a Sector From a Crappy Folding Rule

As Jim Tolpin’s article on sectors from the June 2011 issue is getting into the hands of readers, we have had a few questions about the tool.

One question is, of course: “Where can I buy one?”

I don’t recommend you try to purchase a real sector. They are small affairs that were intended more for calculations on the drafting board – not in the shop. You can easily make your own from two sticks and a hinge, which is what I did last week here on the blog.

Or you can put one of the millions of substandard folding rules back into service as a sector.

This morning I took a modern folding rule that had assorted problems (warpage, poor wood selection, coarse markings) and turned it into a sector that folds up and stores compactly.

You can find plenty of folding rules in poor shape at flea markets and on eBay. I see them go for as little as 50 cents. Then it takes about 15 minutes of sanding and knife work to create a simple sector.

— Christopher Schwarz

You can read the full article in the June 2011 issue of Popular Woodworking Magazine.

15 thoughts on “Make a Sector From a Crappy Folding Rule

    1. Mark Dorman

      I bought a 24″ single fold rule. I liked the idea of having 12″ legs with no hinge halfway.
      I marked mine from the center of the pin. There is a discussin going on at George Walkers design blog about this center of the pin or the back of the pin.

  1. rincewind03060

    I would expect the pivot point for the sector to be the center of the hinge pin and that would be the starting point for the 13 divisions. The drawings in the article show the first increment marked from the outside edge of the hinge pin. Am I missing something?

        1. StratMan9000

          Ok, thanks both. My latest obsession has been 0.3mm mechanical pencils. Right now I’m using a Pentel Graph1000, which I think might not be distributed in the US. I want to try their GraphGear1000 sometime. Seems very nerdy.

          Anyways, watching the video again, I saw the 0.3mm printed on the pencil.

    1. blaisepascal

      It looks a lot like the 0.3mm Koh-i-Noor drafting pencils I used to buy (and lose, so I stopped buying $10 pencils). The color is wrong, and it looks like Koh-i-Noor no longer makes that model.

      It’s a dead ringer for an Alvin Draftmatic 0.3mm technical pencil, which looks exactly like my old red drafting pencils, except yellow.

  2. Miller

    So……., would one use a sector to create the subdivisions on the sector one was trying to create, and if so, where did the original sector come from? well?

    1. Niels

      I’m with Al!- This is like finding a 10 dollar bill in you winter coat. I have that exact same crappy new rule-looking-object that has been resigned to a charming decoration in the bottom of at tool drawer.
      ps. is that sander treadle powered or hand cranked :)

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