update readme and dovetail slacks

rack-mount/bottomScrewTray.scad

@@ -0,0 +1,42 @@
+include <./common.scad>
+use <./rackEars.scad>
+
+// Rack mount tray that supports screws on the bottom of the rack-mount item
+
+// Config variables
+//trayAlignment = "middle"; // middle, right, left
+trayWidth = 150;
+trayDepth = 100;
+trayThickness = 3;
+
+mountPoints = [];
+mountScrewType = "m3";
+
+
+bottomScrewTray(u=5);
+
+module bottomScrewTray(u) {
+
+  screwDx = rackMountScrewWidth;
+  echo(screwDx);
+  screwDz = uDiff * u;
+
+  plateLength = screwDx + 2*rackMountScrewXDist;
+  plateHeight = screwDz + 2*rackMountScrewZDist;
+
+  leftScrewDistToTray = 10+4+3;
+  assert(leftScrewDistToTray >= 5);
+
+  leftScrewGlobalX = -leftScrewDistToTray;
+  rightScrewGlobalX = screwDx + leftScrewGlobalX;
+
+  cube(size=[trayWidth, trayDepth, trayThickness]);
+
+  translate(v=[rackMountScrewXDist+leftScrewGlobalX+3,0,rackMountScrewZDist])
+  rackEarModule(frontThickness=3,sideThickness=3,frontWidth=leftScrewDistToTray, sideDepth=trayDepth-3, u=5);
+
+  translate(v=[rightScrewGlobalX,0,rackMountScrewZDist])
+  mirror(v=[1,0,0])
+  rackEarModule(frontThickness=3,sideThickness=3,frontWidth=30, sideDepth=trayDepth-3, u=5);
+
+}