Sketch the circles which the joints travel through.
Put together the linkage, using magnets as "ground", and bolts as joints.
Sketch the tangent velocity lines.
Extend the links as lines to find the instant center for your linkage configuration.
If you'd like to test this idea more, set up the linkage using the large circle as the center link. "Aim" the links at one of the holes in the circle, place markers in several of the holes, and wiggle the linkage a bit. The hole you have aimed for should only have a marker dot, while there will be longer lines at the other holes.
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