15.00° miter (cut) angle
Set your miter gauge or saw to 15.00° — both ends of every segment, 12 segments per ring. Tiny angle errors stack: 12 segments × 2 cuts means a 0.1° error becomes 2.4° of gap.
Lengths are along the segment edges (circumscribed ring), so the glued ring finishes slightly proud of 10.0″ — you turn it down to final size. Cut a test ring from scrap first.
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