Sector 7G

Last fall I spent a weekend at the Port Townsend school of woodworking and took a two day seminar on hand planes.  The main instructor was Jim Tolpin - I found his two day seminar both relaxing and invigorating all at once. 

After the course I picked up his book the New Traditional Woodworker.  I then picked up By Hand & Eye which he co-authored with George Walker.  Both books make mention of an essential hand tool called a sector.  They both describe what it does - however, neither book describes how to build one.

I finally found a blog entry on the georgewalkerdesign blog.  It's a bit tedious to find, so here is the link.

I made mine out of scrap two-foot long oak strips.  In hindsight I should have used maple which is lighter and perhaps easier to read, but oak works.  My wife had purchased these for some craft a few years ago but she never wound up using them, so that's another reason I wound up using these up.

All I did was square up the sticks to the exact same dimensions, and then I used a set of dividers to make 11 equal steps on each board.  I then used a marking knife to square the steps across the face and edges of the sticks.

I then went over the knife marks with a sharpie and numbered each line up to 11.  Yes I like Spinal Tap.  I finished up with two coats of clear shellac.

Make sure the distance from the hinge pin to
the first mark is the same as all the other divisions.

The only tricky part about designing this thing is ensuring that you account for the hinge.  Whatever the distance between your lines needs to be the same from the first line to the rear of the hinge post.  Some people say it should be the centre but in the end that doesn't matter so much.  What matters is that you don't do what I did initially and mark the first line to the front edge of your stick- that skews your measurements.

After that you just need to learn how to use it - which is actually easier than building it since it involves very little thinking or math.