First of all, the bottom of the workpiece should be leveled with a large area. You can choose several pieces of solid or leftover materials, especially the two ends and middle parts of the four corners of the workpiece. It is best to pad them to 80% of the workpiece area. If you can still clamp them, you can omit the four corners of the support, but the width of the support should be slightly larger, so don't worry about saving and convenience. I can guarantee that your stepping stone is not as valuable as the big board you want to make and there is not enough support. Nine times out of ten, the big board you want to process will have a vibrating knife, and the four corners are uneven in size. Due to the long length of the workpiece, it is impossible to ensure the uniform stress on the whole edge during clamping, that is to say, there is no clamping in some places, so the machining accuracy cannot be guaranteed in some places because of vibration.

If it is a large aluminum plate, I have tried that the material is deformed by heating because of material problems, which can be solved by slowing down the feed, but buying a better aluminum plate is generally not so easy to deform.