The heavy, inner, silkscreen circle marks the area under the screw head and the outer circle is the diameter of the washer.) And, they look kind of sexy in printed documentation - like I have my feces amalgamated when it comes to drafting a printed wiring board. Those lines help me place the dimensions after the board is complete. The lines are on the layer I will use for the board dimensions - “Dwgs.User” - but you may prefer “Cmts.User” or one of the ECO layers. On each mounting hole footprint I place two thin lines (6 mils thick) to mark the center of the hole. My mounting holes are actually defined as footprints. Either do a right-click and “Move Block exactly”, or tap the spacebar and use the relative position readout (bottom of the screen) to relocate those objects where you want to work with them. After everything is in place, make a block selection of all of it. Ignore the drawing frame, title block, etc. Place all of the edge cuts, mounting holes, critical components (or temporary lines marking their positions). I’m rather fond of using the absolute location. The “reference location” on your board might be a corner, the position of a switch or connector, etc. Start the board layout by positioning a reference location at some place in the coordinate system that makes mental math easier. For either one it’s easier to locate the board outline, mounting holes, and possibly critical component locations as the first step, before importing the netlist, etc: I have used two methods to work around KiCAD’s shortcomings in this area. Of course, actually determining what the absolute location should be is typically an absolute pain in the keister! It would be SO HELPFUL if we could define co-ordinate origins at some convenient place on a board - a corner (any corner!), the centroid, a mounting hole or locating notch, etc. Enter the absolute location of the object down to a few Angstroms, or picofurlongs, or whatever your favorite units are.
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