Thanks Boyan. Your machine must be super accurate if you can cut through without marking the undersheet. I have a metal matrix table and neoprene gasket material is fed into the matrix slots to form the vacuum to the the areas where i want to cut. Under vacuum the gasket compresses, more or less flush to the bed, but not 100%. This would certainly preclude only cutting to the spoilboard top, and all the large flatbed routers that I have seen ALWAYS leave a witness mark of some description. G.