Will this cause movement issues?

[Bubbles]

Hello all. I’m making an octagon poker table. The rails are 7.5” x 22” maple and walnut with a maple inlay. The center of the octagon will be mdf covered in felt. I plan to attach the rails to a plywood substrate with screws and elongated holes to allow for wood movement. I want to attach a maple apron flush to the top of the rails giving a 3/4” frame around the rails, but I’m afraid that will cause movement issues.  Am I correct in this assumption? My second choice would be to put the apron under the rails allowing the rails to move without restriction. Is this a safe option?

Thank you for your help

[wtnhighlander]

Wood expands and cotracts much more across than grain than along the grain. If you attach those solid wood pieces to a single piece of ply or mdf, they will swell across their width by a small amount, but they will also push against each other where they meet, increasing the force against the substrate.

Why not assemble these pieces as a seperate component, along with the aprons you mentioned around the edge. This would form a continuous 'rim' that could simply drop over the table top, with space all around for movement. You might get away without fastening it at all, or at least using screws in very loose holes, up through the substrate. Fender washers would be useful, as this shape will have movement in multiple directions.

[wdwerker]

Yea, I would make the frame as a unit, all the grain going in a circle, nothing crossgrain. Attach the center with screws through oversized holes 3/8 or so with a fender washer on a round head screw. Tighten the screw then back it of a 1/4 to 1/2 turn. I would use ply over MDF(which may sag over time). Decent ply, not pine construction ply if possible.