8 Inch 270 Grit Electroplated Diamond Disk

There is a very simple way to confirm this. As you are about to remove your piece from the rough grit wheel, hold it in one place for a few seconds so that all the scratches from the rough grit are going in one direction. When you grind your piece ...

This is almost always caused by using too much water on the finer grits. What's happening is you are hydroplaning on the disk. As you are grinding, you are actually floating on top of a layer of water, every so often you will displace enough of the water...