Bunch of updates.

replacement-parts/keycaps/ctrl-key.scad

@@ -1,11 +1,11 @@
 $fn=180;
 ow=23;      // outer width
 od=18;      // outer depth
-oh=10;    // outer height
+oh=10;      // outer height
 ep = 0.01;
 
 iw=17.4;    // inner width
-id=12.5;      // inner depth
+id=12.5;    // inner depth
 ih=7.6;     // inner height
 
 sphMul = 4;
@@ -51,6 +51,10 @@ difference() {
       ct = 1.3; // cross thickness
 
       // inner cylinder
+      // there are conflicting constraints here: the diameter needs to be thick
+      // enough to have strong walls, particularly at the points where the
+      // cross cutaway comes close to them, but the whole cylinder also needs
+      // to fit into the recess allowed in the keypost
       color("DimGray") translate([ow/2, od/2, 1.4]) cylinder(d=5.3, h=ih - 1.4);
 
       // inner cross recess (post hole)