Hi guys I have a Workbee 1010 where I have (2) 3/4 MDF boards. The bottom one is held down its self tappers to the extrusion frame and the top MDF is screwed to the bottom one by recessed screws 2 inches from the border. I also have a few screws going in a cross pattern. The problem I have is that the MDF cupped after I surfaced it; I added more screws, but it retained a slight spring movement at the borders. What’s the best way to prevent MDF from cupping? This past weekend I surfaced 5 mm off and engraved a cabinet door out of MDF; as soon as I cut the tabs off, it also cupped. I am in South Florida where it is quite humid. My guess is that the factory side of an MDF board is not allowing moisture to penetrate as fast as the milled side. Would milling both sides keep the board flat or flatter? Would it be also the way to go with my spoiler board? I have tried to remove the cup but have not had good results.
I know MDF is popular, but particleboard is about 10 bucks per sheet cheaper and both sides are "equally" exposed to the elements. It is what I use. But, I also use two sheets of 3/4" thick for my work surface. The top one is the spoil board. The extra weight may help. I have noticed that mdf I have in my shop always develops a curve whereas the particleboard does not. But maybe I am storing it improperly.
