Truing The New 30-60-90 Triangle Square, Part Deux

To judge and tune the angles of the square I first establish the right angle to be as perfect as possible with my Vesper square, which is the reference I use for anything 90-degrees in the shop.

With with my brass triangle laid out as closely as possible to the geometric model of the base being exactly 1/2 of the hypotenuse, I begin to mark the 30-degree angles cumulatively to form a half circle or even an entire 360-degree construct.  I have found that simply marking the angle with a pencil and building the angle construct from that is not accurate enough to get it exactly 30-degrees.

When I am creating the sawing and shooting jigs for parquetry I have to keep in mind that in order for the assembly to be perfect the pieces have to fit tightly together by incorporating twelve lines — six starburst pieces with two sides each.  For every fraction of a degree of angle the triangle square is off, that error will be magnified twelve times in the final assembly.

Once that is accomplished I set the square down against a line, then lay a popsicle stick along  the angled line.

Removing the square and placing a second stick as the mating surface I now have the reference line to establish the second 30-degree angle. I continue this process until I get to the stage where, if perfect, the first line and the last line are perfectly in accord.

This never happens, the aggregate is always off by a tiny bit and the hypotenuse needs a bit of adjusting, in this case less than 1/64th”.

I do this on my granite block with a roll of 60-grit sanding medium, gently pressing the toe or the heel of the hypotenuse to kiss the angle a teensy bit one way or the other.

It usually takes me a few brief sessions at the granite-and-sandpaper before I am satisfied with the six-angle exercise.

Once I get to that point I can solder the shoe on the short leg of the square and finish it off, calling it “done.”  This example is the bigger sibling of the current one, made during the workshop two summers ago.  I trued this square the exact same way, and it is a joy to hold and use.