I've just created a compass rose to place in a semi-circular stair tread. (The bottom two stairs of our stair case look like a wedding cake. The top of the cake is a large square area with a half-circle edge.) Wood materials are black walnut and European sycamore, embedded in a square of black cherry, and it is a full 3/4 inch thick. The rose diameter and square are a little under 19 inches, so the diamond shaped pieces and triangles that make up the work are small. The background stair surface will be 3 inch oak flooring. Sub-floor on that flat area is 3/4 inch birch ply (the really stiff stuff), is well supported, and topped with another 1/4 inch underlayment, glued down with polyurethane adhesive.

Should I groove the edges of the pieces to match the oak flooring and attempt to toe-nail these into place, or should I just glue down the whole thing? The whole thing will be saturated with oil-based polyurethane, so I am less worried about expansion than I might otherwise be.

Thanks in advance for any advice.

GT

Medallions are typically glued to a plywood backer board. Then the entire medallion is glued in place. Since your compass design is the same thickness as the flooring, you cannot do this. I would dry fit everything first to ensure it all goes together. Make adjustments if needed. Then plan out a glue down application. Piece A goes first, then B, then C and so on. Use a quality urethane adhesive. Are you going to fit the flooring to the compass after the compass is installed, or have you cut out the flooring in the shape of the compass?

Thanks. I was leaning towards gluing.

I will be putting the medallion down at the same time as the flooring. The medallion assembles into a perfect square, with the rose in the middle surrounded by a square of black cherry, so it will be no problem to assemble this with the floor as I go.

P

Just a comment about "saturating" the floor with poly. This will not protect you as well as you might think from excess humidity or other moisture sources.