For fine engraving work often a floating head is used. The reason you need a floating head/depth controller is simple. When making for example a line thickness of 0.2mm with a V engraving bit, the width of the line will change if the table or material is not exactly flat. Since no table of a CNC machine is flat over the entire surface within a hundreds of a mm...
From factory the KRESS milling motors do not come with a wrench to tighthen the locking nut. We have made this very simple tool ourselves, since many clienst are requesting it. The Wrench is 3mm thin, and will fit perfectly unlike normal wrenches which are thick, and can get caught between tooling and the clamping nut.