Mary sketched a quilt layout on ordinary Letter-size paper using her quilting templates, but the final design will be a 30×30 inch layout requiring a suitably upscaled template. Running the numbers suggested a template with curved edges lying on a 70 inch diameter circle, which was easy enough:
The normal-size acrylic template with a 20 inch diameter sits atop the upscaled cardboard version. We decided cardboard would work fine for a single-use tool; should she need one in the future, I have the technology.
It turns out that the inner curve also has a 70 inch diameter: its center point is displaced 200 mm along the center radius from the outer curve. The straight sides are parallel, not radii of either circle.
She decided a much longer template would simplify smooth edge-to-edge curves, so I laid out a skinnier version with a keyed joint in the middle:
The grid represents the OMTech laser’s 700×500 mm platform, so I used LightBurn’s Cut Shapes function to chop the template into two overlapping parts:
The cuts at the keyed ends extend slightly more than needed, but weren’t critical. Similarly, I didn’t worry about kerf compensation for two pieces of cardboard joined by packing tape.
The template looks a lot like a scimitar:
The shorter version had its corrugations running along the short dimension. I put the longer version’s corrugations along the longer dimension, thinking they would prevent bending. That was true, but they also interfered with the pencil tracing the curves. Next time, I’ll know better!