Shaper Origin Notes #2: Making a Sector

 Blog entry by Rich posted 10-21-2020 03:54 AM 558 reads 1 time favorited 6 comments
 « Part 1: Intro Part 2 of Shaper Origin Notes series Part 3: The Shaper Workstation arrived »

There is also a forum thread going on about the Shaper Origin.

This post refers to the sector. It was invented by Galileo and has been used by astronomers, navigators and craftsmen throughout the centuries.

Back before the days of calculators and online references, non-numerical solutions were the rule. Think slide rule. I have ballistic charts from the 19th century that they used to calculate trajectories—all with a ruler and a set of lines.

The sector is similar. The classics have the Line of Lines, Line of Polygons and Line of Circles. I chose for this pass to only implement the Line of Lines. It’s the most useful to the modern woodworker who already has access to a calculator for radius, diameter and circumference (Line of Circles). Same for the Line of Polygons.

I’ve always wanted to build a nice sector, but never pulled it off well enough to be satisfied with the result. I figured the Shaper was a perfect way to make one that’s accurate.

These are the arms I made using curly maple. I cut them with the Shaper Origin using a SVG design I created with Affinity Designer on my Mac. The same thing could be accomplished using Adobe Illustrator, Corel Draw and others. See the JPG export of the design below.

They are getting lacquered now and I’ll be filling the lines and numerals with Blendal powder and shellac. The idea is that I can fill the areas with the pigmented shellac and then wipe the overflow on the surface clean with DNA, which won’t affect the lacquer base. It’s a technique I use often doing touch-ups.

This is the second iteration. The first try had some errant cuts that required changes to the vector file layout. I’ll likely be doing a third version with 1/16” OD brass tube inserted into the points instead of the little crosshatches. The purpose of that is to get a perfect registration with the dividers and also to not wear with use. For that, I’ll be using a 1/16” straight cut router bit in the Shaper Origin to precisely locate and drill the holes for the inserts.

One of the trickiest parts of the build was getting the Shaper Origin registered in the hinge areas to do the milling (basically a half-lap). More about that later.

And here’s the JPG export of the design:

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner