Finally solved the challenge of securely holding down warped plywood (1/4” to 1/16”).
Most of my work is with 12”x24” sheets of plywood.
Installed T Tracks on the edge of the bed rails along the X and Y axes and used a combination of standard and mini T track clamps. The clamps are infinitely adjustable along the T track to hold where most needed.
The clamps easily reach the edges of the material and interferes minimally with the travel of the laser nozzle/cone.
The T bolts are 1 1/2” to clear the gantry.
Be sure to remove any clamps before lowering the bed on the Z axis!
I made a bunch of honeycomb pins from scrap wood and use them in combination with magnets.
Along the edges of the material if a magnet will interfere with cutting or head travel I use the pins… everywhere else including the middle of material I use the magnets being careful to keep them out of way of the laser head.