I want to match the existing radius on my stairs trim, but I'm unsure what size rounding over bit I need to get. I measured the arc of the radius the best I could with a flexible tape measure and it's about 9/16". I did the math and that equates to a 0.6" radius, which is close to 5/8". Perhaps I'm not measuring correctly. Is there a common radius for 3/4" board?
Best Answer
There are a brazillion router bit roundover sizes. From somewhere with a gentle return policy, buy the one you think you need plus sizes above and below.
Or if you're going to a brick+mortar, you could create a profile template (stiff cardboard) of your stair and compare it with what's on the shelf.