Casette cover

docs/Notes.md

@@ -151,22 +151,22 @@ Performance
 - simple models for preview, e.g. simplify the table based curves
 
 
-README Notes
-============
+Videos
+======
 
-- extended for keyboard to -X, -Y, same angles and curves, except curves in keyboard area
-- which keyboard to use, how to mount it
-- which display to use, how to mount it
-- how to adjust the model (dimensions, "custom", link to DEC diagrams)
+https://www.youtube.com/watch?v=nb2bxaj79rc
+https://www.youtube.com/watch?v=ksL232PHivI
+https://www.youtube.com/watch?v=3gNN4nL5F-k
 
 
 TODOs
 =====
 
 - rename outside to !mask in body models
 - terminal top and bottom are an interference between the two body planes, you can see it if you color body_xy red
-- screen bezel interferes with body vertical front, move screen bezel back by DELTA
+- screen bezel and cassette mask interfere with keyboard surface, move screen bezel/cassette mask back by DELTA?
 - move some of the _dimensions that are not shared between files into the .scad file that uses them
   - comment out dimensions that are not yet used at all
 - Section AK-AK Sheet 10: Display top has 5 stiffening ribs
   - add stiffening ribs to other places as well
+- rotate the model for easy viewing (needs also adjusting make preview)

model/Makefile

@@ -1,4 +1,4 @@
-TARGETS=shell.stl vt52.stl
+TARGETS=cassette_cover.stl shell.stl vt52.stl
 PREVIEWS=$(TARGETS:.stl=.png)
 
 all: $(TARGETS)

model/body.scad

@@ -25,10 +25,9 @@ module body_yz_half(outside) {
         body_yz_half_plane(outside, XZ_CURVE_Y000[3], YZ_CURVE_X150),
         body_yz_half_plane(outside, XZ_CURVE_Y000[4], YZ_CURVE_X200),
         body_yz_half_plane(outside, XZ_CURVE_Y000[5], YZ_CURVE_X250),
-        body_yz_half_plane(outside, XZ_CURVE_Y000[6], YZ_CURVE_X300),
-        body_yz_half_plane(outside, XZ_CURVE_Y000[7], YZ_CURVE_X350),
-        body_yz_half_plane(outside, XZ_CURVE_Y000[8], YZ_CURVE_X400),
-        // TODO decide depth of the model
+        // body_yz_half_plane(outside, XZ_CURVE_Y000[6], YZ_CURVE_X300),
+        // body_yz_half_plane(outside, XZ_CURVE_Y000[7], YZ_CURVE_X350),
+        // body_yz_half_plane(outside, XZ_CURVE_Y000[8], YZ_CURVE_X400),
     ];
 
     // The keyboard area is extended into -X by extend_fwd_bot_x, so we need to space the keyboard area

model/body_dimensions.scad

@@ -25,8 +25,8 @@ BODY_WALL = 4; // custom
 // Calculate missing coordinates
 kbd_fwd_x = adj_ang_to_opp(KBD_FWD_Y, KBD_FWD_A);
 
-//echo("kbd_fwd_x", kbd_fwd_x);
-//echo("KBD_FWD_Y", KBD_FWD_Y);
+// echo("kbd_fwd_x", kbd_fwd_x); // 7.79423
+// echo("KBD_FWD_Y", KBD_FWD_Y); // 13.5
 
 /* Top back point of the keyboard
 kbd_back_x and kbd_back_y are only defined by KBD_FWD_A and KBD_TOP_A
@@ -49,8 +49,8 @@ x = (kbd_fwd_x * tan(KBD_TOP_A) - KBD_FWD_Y - SCR_TOP_X * cotan(SCR_FWD_A) + SCR
 kbd_back_x = (kbd_fwd_x * tan(KBD_TOP_A) - KBD_FWD_Y - SCR_TOP_X * cotan(SCR_FWD_A) + SCR_TOP_Y) / (tan(KBD_TOP_A) - cotan(SCR_FWD_A));
 kbd_back_y = kbd_back_x * tan(KBD_TOP_A) - kbd_fwd_x * tan(KBD_TOP_A) + KBD_FWD_Y;
 
-//echo("kbd_back_x", kbd_back_x);
-//echo("kbd_back_y", kbd_back_y);
+// echo("kbd_back_x", kbd_back_x); // 130.303
+// echo("kbd_back_y", kbd_back_y); // 41.7833
 
 // Extend the model to -Y and shorten the front edge to fit a larger keyboard; custom
 EXTEND_Y = 6;
@@ -72,7 +72,7 @@ extend_fwd_bot_x = extend_fwd_top_x - kbd_fwd_x + ang_adj_to_opp(KBD_FWD_A, KBD_
 YZ_TOP_CORNER_R = 20; // Sheet 6, Section AA-AA
 
 // X values for which we have YZ_CURVE_X* tables
-YZ_X = [0, 50, 100, 150, 200, 250, 300, 350, 400];
+YZ_X = [0, 50, 100, 150, 200, 250/*, 300, 350, 400*/];
 
 // Values from Sheet 29, Data List #1 for X values in YZ_X
 XZ_CURVE_Y000 = [
@@ -82,9 +82,9 @@ XZ_CURVE_Y000 = [
     262.07143,  // X = 150
     262.78571,  // X = 200
     263.26191,  // X = 250
-    263.50000,  // X = 300
-    263.50000,  // X = 350
-    263.29190,  // X = 400
+    // 263.50000,  // X = 300
+    // 263.50000,  // X = 350
+    // 263.29190,  // X = 400
 ];
 
 // Sheet 5

model/cassette_cover.scad

@@ -0,0 +1,123 @@
+// use
+include <common.scad>
+include <cassette_dimensions.scad>
+include <BOSL2/std.scad>
+
+// TODO locating features on cover
+// TODO mounting tabs on cover
+
+module cc_cover_handle() {
+    move([
+        -CC_VISIBLE_DEPTH + DELTA,
+        scr_fwd_height - CC_HANDLE_POS,
+        CC_HANDLE_MARGIN_Z
+    ])
+        cuboid(
+            [CC_HANDLE_DEPTH, CC_HANDLE_HEIGHT, cc_mask_width - 2 * CC_HANDLE_MARGIN_Z],
+            rounding = CC_HANDLE_R,
+            edges = [LEFT + TOP, LEFT + BOTTOM],
+            anchor = RIGHT + BOTTOM + FRONT
+        );
+}
+
+//cc_cover_handle();
+
+// Cover plane, same height as forward screen plane + margin except at the bottom
+function cc_cover_plane(dist) =
+    // Generate plane for given distance from the screen plane
+    // Bottom corner rounding is applied later
+    let(
+        extra_bot = sign(dist) * ang_adj_to_opp(KBD_TOP_A + SCR_FWD_A, abs(dist)),
+
+        shape = [
+            [0 - CC_COVER_MARGIN, 0 - extra_bot],                                   // bottom left
+            [0 - CC_COVER_MARGIN, scr_fwd_height + CC_COVER_MARGIN],                // top left
+            [cc_mask_width + CC_COVER_MARGIN, scr_fwd_height + CC_COVER_MARGIN],    // top right
+            [cc_mask_width + CC_COVER_MARGIN, 0 - extra_bot]                        // bottom right
+        ],
+
+        radii = [0, CC_TL_R, CC_TR_R, 0]
+    )
+    round_corners(shape, radius = radii, $fn=fn_where_needed);
+
+module cc_bottom_corner_mask() {
+    // Rounding for bottom corners
+    // Needs to be applied after skin(), because it causes different
+    // count of vertices between front and back side of the cover
+
+    // Bottom corner mask depth, needs to clear CC_B_R at an angle
+    mask_depth = CC_B_R * 2;
+
+    // Duplicate for the near corner
+    zflip_copy(z = cc_mask_width / 2)
+        // Top corner of the mask should be perpendicular to the cover, not to the keyboard surface
+        difference() {
+            // Rotate the mask to match cassette_mask angle, centered on the back face corner which is [0, 0, 0]
+            zrot(KBD_TOP_A + SCR_FWD_A)
+                yrot(-90) // orient relative to the model
+                    rounding_edge_mask(
+                        l = mask_depth,
+                        r = CC_B_R,
+                        excess = CC_COVER_MARGIN + DELTA
+                    );
+
+            ymove(CC_B_R)
+                cuboid(
+                    mask_depth,
+                    anchor = FRONT
+                );
+        }
+}
+
+// cc_bottom_corner_mask();
+
+module cc_cover_object() {
+    // Position the forward face
+    fwd_face = apply(
+        // Transformations are applied last to first
+        IDENT
+            * xmove(-CC_VISIBLE_DEPTH) // cover depth
+            * yrot(-90), // orient relative to the model
+        path3d(cc_cover_plane(CC_VISIBLE_DEPTH))
+    );
+    // stroke(fwd_face, closed=true);
+
+    // Position the back face
+    back_face = apply(
+        // Transformations are applied last to first
+        IDENT
+            * yrot(-90), // orient relative to the model
+        path3d(cc_cover_plane(0))
+    );
+    // stroke(back_face, closed=true);
+
+    // Cover without the bottom corners
+    faces = [fwd_face, back_face];
+    skin(faces, slices = 10);
+}
+
+module cc_cover() {
+    // Angle and move the cover together with the corner mask
+    move([kbd_back_x, kbd_back_y, CC_MASK_LEFT_Z]) // move to position relative to the model
+        zrot(-SCR_FWD_A) // angle relative to the model
+            difference() {
+                union() {
+                    cc_cover_object();
+                    cc_cover_handle();
+                }
+
+                cc_bottom_corner_mask();
+            }
+}
+
+// %polygon(cc_cover_plane(CC_VISIBLE_DEPTH));
+// polygon(cc_cover_plane(0));
+
+// use <body.scad>
+// xrot(90) {
+//     %body(true);
+//     cc_cover();
+// }
+
+xrot(90)
+    cc_cover();

model/cassette_dimensions.scad

@@ -0,0 +1,97 @@
+// include
+include <common.scad>
+include <body_dimensions.scad>
+include <screen_dimensions.scad>
+include <BOSL2/std.scad>
+
+// "Cassette cover", dark cover on the right side of the screen
+
+// Notes:
+//
+// The bottom edge of the original cover probably rests on the keyboard plane, in the model
+// we instead fully support it from the back on all sides, since it's easier.
+
+// Cover height discussion:
+//
+// Bottom back edge of the cover is at Y = kbd_back_y = 41.78.
+// Cover height is CC_HEIGHT = 230.5, angled at SCR_FWD_A = 12.
+// Cover height in Y is CC_HEIGHT * cos(SCR_FWD_A) = 225,46.
+// Top edge of the cover is then at Y = kbd_back_y + 225,46 = 267.24.
+// Top edge of the screen is defined as SCR_FWD_TOP_Y = 264, which is 3.2 mm lower.
+// The bottom edge of the cover is angled (Page 6, Item #2), that explains about 0.8 mm in Y direction.
+// That makes the cover about 2.4 mm larger than the screen viewport,
+// suggesting the margins (CC_COVER_MARGIN) are about 1.2 mm.
+//
+// The photos seem to show the cover slightly taller than the screen viewport.
+// Even photos taken from above, where parallax is not an issue.
+// The space at the bottom of the louvres (Section AF-AF) is 4 mm,
+// and the cover looks like it hides about one quarter of that.
+//
+// Decision: Cover mask has the exact vertical location of the screen viewport.
+// Cover itself is 1 mm larger than the mask in every direction except bottom (CC_COVER_MARGIN).
+// Cover corners are same as screen corners, do NOT add 1 mm to their radius.
+// Cover is supported by the mask on all sides, with four tabs holding it in.
+
+// Cover bottom discussion:
+//
+// Based on YouTube videos, the cover very slightly overlaps the hole and it rises perhaps
+// 1 mm over the screen surface. It is not completely embedded in the body.
+// Based on the videos and on higher res pictures, there is something strange going on with
+// borders of the body hole at the bottom, where it touches the kbd/scr fillet.
+// There is a discontinuity.
+//
+// The rounded corners at the bottom are R5 and match the R5 hole in the body.
+// The kbd/scr fillet is R14, which means the corners interfere with top of the fillet.
+// This is solved by masking of the part of the fillet that interferes with the back side
+// of the corners, which is the "something strange" in the pictures.
+//
+// Specifically, what interferes is the back side of the outside corners of the bottom notches.
+// The fillet is already moving away from the screen plane here. Also, the outside corners are
+// definitely 90 degrees to the rest of the cover in all directions.
+//
+// Decision:
+// The notches at the bottom of the cover are creating an overlap over screen plane,
+// 1 mm wide on all sides except bottom. Cover bottom sits on keyboard top plane.
+// In order to solve the interference between R5 and R14 shapes, top of the R14 fillet
+// will be masked off to be in screen plane, allowing space for outside bottom corners
+// of the cover.
+
+// Page 6, Sheet 1, Cassette Cover
+
+// These are unused (see discussion above), instead we derive them from body dimensions
+// CC_HEIGHT = 230.5;
+// CC_WIDTH_Z = 166;
+
+// Depth of the cover above screen plane
+CC_VISIBLE_DEPTH = 1; // estimated
+
+// Difference between cover size and mask size; custom
+CC_COVER_MARGIN = 1;
+
+// Handle
+
+// Space left and right of the handle; estimated from photos
+CC_HANDLE_MARGIN_Z = 1;
+
+// Top of the cover to bottom of the handle
+CC_HANDLE_POS = 205;
+
+// Visible handle depth; partly from drawings and partly estimated
+CC_HANDLE_DEPTH = 12; // custom; original is (20 - estimated 4)
+
+CC_HANDLE_HEIGHT = 2; // estimated
+
+// Handle corner rounding; custom
+CC_HANDLE_R = 1;
+
+// Page 13, Sheet 2, Shell VT50, View E-E
+
+// Let's use the screen constants to make sure they are kept in sync
+CC_TR_R = SCR_FWD_TL_R;
+CC_TL_R = SCR_FWD_TR_R;
+CC_B_R = SCR_FWD_BR_R;
+
+// This does not match CC_WIDTH_Z, the difference is 6.5 mm, that's why we don't use CC_WIDTH_Z
+CC_MASK_LEFT_Z = 63;
+CC_MASK_RIGHT_Z = 222.5;
+cc_mask_width = CC_MASK_RIGHT_Z - CC_MASK_LEFT_Z;