Just a comment on securing plywood atop a Mianne framework:
I am completing a 10' by 5' layout on a 9' by 4' Mianne frame. I placed two 5' by 5' pieces of 1/2-inch 9-ply birch plywood atop the Mianne frame, aligned them with the framework, then got under the table and glued four 3" by 3" by 1/2-inch thick blocks to the underside of the plywood (not to the framework) at each inside-corner of the Mianne framework. I left a small clearance (perhaps .01" or .02") between the edges of the blocks and the framework to allow for differential expansion - which has never been evident. I applied layers of extruded pink foam atop the plywood to create the terrain. There are three cross-members in the frame so each 5' by 5' piece of plywood is supported at the center of the table, 6 inches from the other three edges, and in its middle. I did it this way because I wanted to be able just to lift the plywood off the framework and take the layout elsewhere if I move. The weight of the plywood has been sufficient to keep it, and the track surface, perfectly flat. I did not find it necessary to fasten the plywood to the framework. It simply lays on top and is kept in position by the small blocks at the undersides of the corners. Just my two-cents...
MELGAR
