screw_polysink now has an alternating layer option to be more printable inverted.

The screws test now tests polysinks and has printable sample.

readme.md

@@ -2904,6 +2904,8 @@ These items are sysmtrical, so by default the origin is in the centre but it can
 ## Screws
 Machine screws and wood screws with various head styles.
 
+For an explanation of ```screw_polysink()``` see <https://hydraraptor.blogspot.com/2020/12/sinkholes.html>.
+
 
 [vitamins/screws.scad](vitamins/screws.scad) Object definitions.
 
@@ -2930,9 +2932,10 @@ Machine screws and wood screws with various head styles.
 | Function | Description |
 |:--- |:--- |
 | ```screw_boss_diameter(type)``` | Boss big enough for nut trap and washer |
-| ```screw_head_depth(type, d)``` | How far a counter sink head will go into a straight hole diameter d |
+| ```screw_head_depth(type, d = 0)``` | How far a counter sink head will go into a straight hole diameter d |
 | ```screw_longer_than(x)``` | Returns shortest screw length longer or equal to x |
 | ```screw_nut_radius(type)``` | Radius of matching nut |
+| ```screw_polysink_r(type, z)``` | Countersink hole profile corrected for rounded staircase extrusions. |
 | ```screw_shorter_than(x)``` | Returns longest screw length shorter than or equal to x |
 
 ### Modules
@@ -2940,7 +2943,8 @@ Machine screws and wood screws with various head styles.
 |:--- |:--- |
 | ```screw(type, length, hob_point = 0, nylon = false)``` | Draw specified screw, optionally hobbed or nylon |
 | ```screw_and_washer(type, length, star = false, penny = false)``` | Screw with a washer which can be standard or penny and an optional star washer on top |
-| ```screw_countersink(type)``` | Countersink shape |
+| ```screw_countersink(type, drilled = true)``` | Countersink shape |
+| ```screw_polysink(type, h = 100, alt = false)``` | A countersink hole made from stacked polyholes for printed parts |
 
 ![screws](tests/png/screws.png)
 
@@ -2979,6 +2983,11 @@ Machine screws and wood screws with various head styles.
 |   1 | ```screw(No6_cs_screw, 30)``` |  Screw No6 cs wood x 30mm |
 |   1 | ```screw(No6_screw, 30)``` |  Screw No6 pan wood x 30mm |
 
+### Printed
+| Qty | Filename |
+| ---:|:--- |
+|   1 | polysink.stl |
+
 
 <a href="#top">Top</a>
 

tests/screws.scad

@@ -18,20 +18,46 @@
 //
 include <../core.scad>
 
-module screws()
-for(y = [0 : len(screw_lists) -1])
-    for(x = [0 : len(screw_lists[y]) -1]) {
-        screw = screw_lists[y][x];
-        if(screw) {
-             length = screw_head_type(screw) == hs_grub ? 6
-                    : screw_radius(screw) <= 1.5 ? 10
-                    : screw_max_thread(screw) ? screw_longer_than(screw_max_thread(screw) + 5)
-                    : 30;
-            translate([x * 20, y * 20])
-                screw(screw, length);
-        }
+module polysink_stl() {
+    stl("polysink");
+
+    cs_screws = [for(list = screw_lists, screw = list) if(screw_head_type(screw) == hs_cs_cap) screw];
+    n = len(cs_screws);
+    size = [n * 20, 20, 10];
+    difference() {
+        translate([-size.x / n / 2, $preview ? 0 : -size.y / 2, -size.z])
+            cube($preview ? [size.x, size.y / 2, size.z] : size);
+
+        for(i = [0 : n - 1])
+            let(s = cs_screws[i])
+                translate([i * 20, 0]) {
+                    screw_polysink(s, 2 * size.z + 1);
+
+                    translate_z(-size.z)
+                        screw_polysink(s, 2 * size.z + 1, alt = true);
+                }
     }
+}
+
+module screws() {
+    for(y = [0 : len(screw_lists) -1])
+        for(x = [0 : len(screw_lists[y]) -1]) {
+            screw = screw_lists[y][x];
+            if(screw) {
+                 length = screw_head_type(screw) == hs_grub ? 6
+                        : screw_radius(screw) <= 1.5 ? 10
+                        : screw_max_thread(screw) ? screw_longer_than(screw_max_thread(screw) + 5)
+                        : 30;
+                translate([x * 20, y * 20])
+                    screw(screw, length);
+            }
+        }
+        translate([80, 140])
+            polysink_stl();
+}
 
 if($preview)
     let($show_threads = true)
         screws();
+else
+    polysink_stl();

vitamins/blowers.scad

@@ -21,7 +21,7 @@
 //                                                   n     d   p   r     r              b   i            r    r                               i    b    s    p    l    g
 //                                                   g     t   t   e     e                  s            e    e                               t         e         l
 //                                                   t     h   h         w              d                w    w                                              t
-//                                                   h                                                  h    s                                         t         t
+//                                                   h                                                   h    s                                         t         t
 RB5015 = ["RB5015", "Blower Runda RB5015",           51.3, 51, 15, 31.5, M4_cap_screw, 26, [27.3, 25.4], 4.5, [[4.3, 45.4], [47.3,7.4]],     20,   14,  1.5, 1.3, 1.2, 15];
 PE4020 = ["PE4020", "Blower Pengda Technology 4020", 40,   40, 20, 27.5, M3_cap_screw, 22, [21.5, 20  ], 3.2, [[37,3],[3,37],[37,37]],       29.3, 17,  1.7, 1.2, 1.3, 13];
 BL40x10 =["BL40x10","Square radial 4010",            40,   40,9.5, 27,   M2_cap_screw, 16, [24,   20  ], 2.4, [[2,2],[38,2],[2,38],[38,38]], 30  , 9.5, 1.5, 1.5, 1.1, 1.5];

vitamins/inserts.scad

@@ -29,7 +29,7 @@
 //                          d         d          h    d    d
 //                                         d
 //
-F1BM2   = [ "F1BM2",    4.0, 3.6, 3.2, 2,   3.0,  1.0, 3.4, 3.1 ];
+F1BM2   = [ "F1BM2",   4.0, 3.6, 3.2, 2,   3.0,  1.0, 3.4, 3.1 ];
 F1BM2p5 = [ "F1BM2p5", 5.8, 4.6, 4.0, 2.5, 3.65, 1.6, 4.4, 3.9 ];
 F1BM3   = [ "F1BM3",   5.8, 4.6, 4.0, 3,   3.65, 1.6, 4.4, 3.9 ];
 F1BM4   = [ "F1BM4",   8.2, 6.3, 5.6, 4,   5.15, 2.3, 6.0, 5.55 ];

vitamins/mains_socket.scad

@@ -116,7 +116,7 @@ module mains_socket(type) { //! Draw specified 13A socket
             cylinder(r = screw_clearance_radius(screw), h = 100, center = true);
 
             translate_z(height)
-                screw_countersink(screw);
+                screw_countersink(screw, drilled = false);
         }
     }
 }

vitamins/rails.scad

@@ -33,11 +33,11 @@ SSR15_carriage = [ 40.3, 23.3, 34, 24, 4.5, 0,  26, M4_cap_screw ];
 //
 //
 //                Wr  Hr   E    P   D    d    h
-MGN5 = [ "MGN5",  5,  3.6, 5,   15, 3.5, 2.4, 0.8, M2_cs_cap_screw, MGN5_carriage, M2_cs_cap_screw ]; // Screw holes too small for M2 heads
+MGN5 = [ "MGN5",  5,  3.6, 5,   15, 3.6, 2.4, 0.8, M2_cs_cap_screw, MGN5_carriage, M2_cs_cap_screw ]; // Screw holes too small for M2 heads
 MGN7 = [ "MGN7",  7,  5,   5,   15, 4.3, 2.4, 2.6, M2_cap_screw,    MGN7_carriage, M2_cs_cap_screw ];
 MGN9 = [ "MGN9",  9,  6,   7.5, 20, 6.0, 3.5, 3.5, M3_cap_screw,    MGN9_carriage, M3_cs_cap_screw ];
 MGN12= [ "MGN12", 12, 8,   10,  25, 6.0, 3.5, 4.5, M3_cap_screw,   MGN12_carriage, M3_cs_cap_screw ];
-MGN12H=[ "MGN12H",12, 8,    10, 25, 6.0, 3.5, 4.5, M3_cap_screw,   MGN12H_carriage,M3_cs_cap_screw ];
+MGN12H=[ "MGN12H",12, 8,   10,  25, 6.0, 3.5, 4.5, M3_cap_screw,   MGN12H_carriage,M3_cs_cap_screw ];
 MGN15= [ "MGN15", 15, 10,  10,  40, 6.0, 3.5, 5.0, M3_cap_screw,   MGN15_carriage, M3_cs_cap_screw ];
 SSR15= [ "SSR15", 15, 12.5,10,  60, 7.5, 4.5, 5.3, M4_cap_screw,   SSR15_carriage, M4_cs_cap_screw ];
 

vitamins/screw.scad

@@ -19,6 +19,8 @@
 
 //
 //! Machine screws and wood screws with various head styles.
+//!
+//! For an explanation of ```screw_polysink()``` see <https://hydraraptor.blogspot.com/2020/12/sinkholes.html>.
 //
 include <../utils/core/core.scad>
 
@@ -41,9 +43,13 @@ function screw_pilot_hole(type)       = type[11];    //! Pilot hole radius for w
 function screw_clearance_radius(type) = type[12];    //! Clearance hole radius
 function screw_nut_radius(type) = screw_nut(type) ? nut_radius(screw_nut(type)) : 0; //! Radius of matching nut
 function screw_boss_diameter(type) = max(washer_diameter(screw_washer(type)) + 1, 2 * (screw_nut_radius(type) + 3 * extrusion_width)); //! Boss big enough for nut trap and washer
-function screw_head_depth(type, d) = screw_head_height(type) ? 0 : screw_head_radius(type) - d / 2 + screw_radius(type) / 5; //! How far a counter sink head will go into a straight hole diameter d
+function screw_head_depth(type, d = 0) =             //! How far a counter sink head will go into a straight hole diameter d
+    screw_head_height(type)
+        ? 0
+        : let(r = screw_radius(type)) screw_head_radius(type) - max(r, d / 2) + r / 5;
 
 function screw_longer_than(x) = x <=  5 ?  5 : //! Returns shortest screw length longer or equal to x
+                                x <=  6 ?  6 :
                                 x <=  8 ?  8 :
                                 x <= 10 ? 10 :
                                 x <= 12 ? 12 :
@@ -244,14 +250,54 @@ module screw(type, length, hob_point = 0, nylon = false) { //! Draw specified sc
     }
 }
 
-module screw_countersink(type) { //! Countersink shape
+module screw_countersink(type, drilled = true) { //! Countersink shape
     head_type   = screw_head_type(type);
     head_rad    = screw_head_radius(type);
-    head_height = head_rad;
+    rad = screw_radius(type);
+    head_t = rad / 5;
+    head_height = head_rad + head_t;
 
     if(head_type == hs_cs || head_type == hs_cs_cap)
         translate_z(-head_height)
-             cylinder(h = head_height, r1 = 0, r2 = head_rad);
+            if(drilled)
+                cylinder(h = head_height + eps, r1 = 0, r2 = head_rad + head_t);
+            else
+                intersection() {
+                    cylinder(h = head_height + eps, r1 = 0, r2 = head_rad + head_t);
+
+                    cylinder(h = head_height + eps, r = head_rad + eps);
+                }
+}
+
+function screw_polysink_r(type, z) = //! Countersink hole profile corrected for rounded staircase extrusions.
+    let(rad = screw_radius(type),
+        head_t = rad / 5,
+        head_rad = screw_head_radius(type)
+    )
+    limit(head_rad + head_t - z + (sqrt(2) - 1) * layer_height / 2, screw_clearance_radius(type), head_rad);
+
+module screw_polysink(type, h = 100, alt = false) { //! A countersink hole made from stacked polyholes for printed parts
+    head_depth = screw_head_depth(type);
+    assert(head_depth, "Not a countersunk screw");
+    layers = ceil(head_depth / layer_height);
+    rmin = screw_clearance_radius(type);
+    sides = sides(rmin);
+    lh = layer_height + eps;
+    render(convexity = 5)
+        for(side = [0, 1]) mirror([0, 0, side]) {
+            for(i = [0 : layers - 1])
+                translate_z(i * layer_height) {
+                    r = screw_polysink_r(type, i * layer_height + layer_height / 2);
+                    if(alt)
+                        rotate(i % 2 == layers % 2 ? 180 / sides : 0)
+                            poly_cylinder(r = r, h = lh, center = false, sides = sides);
+                    else
+                        poly_cylinder(r = r, h = lh, center = false);
+                }
+
+            translate_z(layers * layer_height)
+                poly_cylinder(r = rmin, h = h / 2 - layers * layer_height, center = false);
+        }
 }
 
 module screw_and_washer(type, length, star = false, penny = false) { //! Screw with a washer which can be standard or penny and an optional star washer on top

vitamins/screws.scad

@@ -107,14 +107,14 @@ No6_screw        = ["No6", "No6 pan wood",      hs_pan, 3.5, 6.7, 2.2,    0,   0
 No6_cs_screw     = ["No6_cs", "No6 cs wood",    hs_cs,  3.5, 7.0, 0,      0,   0, 0,   M4_washer, false,    No6_pilot_radius, No6_clearance_radius];
 
 screw_lists = [
-[ M2_cap_screw, M2p5_cap_screw, M3_cap_screw,    M4_cap_screw, M5_cap_screw, M6_cap_screw, M8_cap_screw],
-[ 0,            0,              M3_low_cap_screw],
-[ 0,            0,              M3_hex_screw,    M4_hex_screw, M5_hex_screw, M6_hex_screw, M8_hex_screw],
-[ 0,            M2p5_pan_screw, M3_pan_screw,    M4_pan_screw, M5_pan_screw, M6_pan_screw, No632_pan_screw],
-[ 0,            No2_screw,      No4_screw,       No6_screw,    No6_cs_screw],
-[ 0,            M2_cs_cap_screw,M3_cs_cap_screw, M4_cs_cap_screw],
-[ 0,            M2_dome_screw,  M3_dome_screw,   M4_dome_screw],
-[ 0,            0,              M3_grub_screw,   M4_grub_screw]
+[ M2_cap_screw,    M2p5_cap_screw, M3_cap_screw,    M4_cap_screw, M5_cap_screw, M6_cap_screw, M8_cap_screw],
+[ 0,               0,              M3_low_cap_screw],
+[ M2_cs_cap_screw, 0,              M3_cs_cap_screw, M4_cs_cap_screw],
+[ M2_dome_screw,   0,              M3_dome_screw,   M4_dome_screw],
+[ 0,               0,              M3_hex_screw,    M4_hex_screw, M5_hex_screw, M6_hex_screw, M8_hex_screw],
+[ 0,               M2p5_pan_screw, M3_pan_screw,    M4_pan_screw, M5_pan_screw, M6_pan_screw, No632_pan_screw],
+[ No2_screw,       0,              No4_screw,       No6_screw,    No6_cs_screw],
+[ 0,               0,              M3_grub_screw,   M4_grub_screw]
 ];
 
 use <screw.scad>