Added option for "Slide-in" magnet holes. (#16)

chmarr · Apr 25, 2023 · 7b4e7cd · 7b4e7cd
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diff --git a/README.md b/README.md
@@ -39,7 +39,7 @@ on the expected-to-be-called SCAD modules follows.
 
 There are serveral possible modules to call, specified below with their "signatures":
 
-* `gridfinity_module_base(count, holes=0)`
+* `gridfinity_module_base(count, holes=0, hole_width, hole_height, hole_offset=0.2)`
 * `gridfinity_wall(count, height, z_offset=module_unit_height)`
 * `gridfinity_internal_mass(count, height, z_offset=module_unit_height)`
 * `gridfinity_square_bores(count, size, z_offset, repeat=[1,1], top_radius=0, bottom_radius=0, top_sides=[1,1,1,1], bottom_sides=[1,1,1,1])`
@@ -60,7 +60,10 @@ and the stacking lip will usually appear higher.
 ### gridfinity_module_base
 Creates the container base, including the X x Y inserts and a overall base layer. Always 7mm high. The origin of this and other features
 is the bottom-center of the *first* insert.
-* *holes* -- Selects to put holes in the bottom of the module, as per spec. 0-No holes. 1-Holes in corners only. 2-Holes everywhere.
+* *holes* -- Selects to put holes in the bottom of the module, as per spec. 0-No holes. 1-Holes in corners only. 2-Holes everywhere. 3-Slide-in holes in corners
+* *hole_width* -- The width of a slide in hole. Typically very slightly smaller than the magnet to allow it to be wedged in. (Only if holes==3)
+* *hole_height* -- The height of a slide in hole. Typically this is slightly larger than the magnet to account for variability. (Only if holes==3)
+* *hole_offset* -- The vertical offset of the hole from the bottom. Typically just one or two layer's worth to keep the magnet close to the base magnets. (Only if holes==3. Defaults to 0.2)
 
 ### gridfinity_wall
 Creates the wall around the outside of the box.

diff --git a/gridfinity_boxes.scad b/gridfinity_boxes.scad
@@ -22,6 +22,7 @@ module_unit_height=7;
 module_internal_square = module_side - 2*module_radius_1;
 internal_radius = module_radius_3;
 internal_side=module_side - 2*(1.9 + 0.7);
+hole_offset_from_radius_3 = 4.8;
 
 // ***************************************************************************
 // The following functions and modules are not expected to be called directly.
@@ -108,7 +109,6 @@ module gridfinity_base_hole() {
 //           A 4-tuple, being these corners [back-right, back-left, front-left, front-right]
 module gridfinity_base_holes(corners=[1,1,1,1]) {
     // Constants derived_from_spec_sheet
-    hole_offset_from_radius_3 = 4.8;
     offset = module_side/2 - module_radius_1 + module_radius_3 - hole_offset_from_radius_3;
     if (corners[0]) {
         translate([offset,offset]) gridfinity_base_hole();
@@ -234,6 +234,26 @@ module gridfinity_single_square_bore(size, top_radius=0, bottom_radius=0, top_si
     }
 }
 
+// creates an object to remove the mass required to insert a magnet.
+module gridfinity_magnet_single_hole(hole_width, hole_height){
+    slot_length = hole_offset_from_radius_3 - module_radius_3 + module_radius_1;
+    cylinder(d=hole_width, h=hole_height);
+    translate([-slot_length-epsilon, -hole_width/2, 0]) cube([slot_length+2*epsilon, hole_width, hole_height]);
+}
+
+// creates an object to remove the mass required to insert a magnet at each of the corners
+module gridfinity_magnet_holes(count, hole_width, hole_height) {
+    offset = module_side/2 - module_radius_1 + module_radius_3 - hole_offset_from_radius_3;
+    // back right
+    translate([module_spacing*(count.x-1)+offset, module_spacing*(count.y-1)+offset]) rotate([0,0,180])gridfinity_magnet_single_hole(hole_width, hole_height);
+    // back left
+    translate([-offset, module_spacing*(count.y-1)+offset]) rotate([0,0,-90]) gridfinity_magnet_single_hole(hole_width, hole_height);
+    // front left
+    translate([-offset,-offset]) gridfinity_magnet_single_hole(hole_width, hole_height);
+    // front right
+    translate([module_spacing*(count.x-1)+offset, -offset]) rotate([0,0,90]) gridfinity_magnet_single_hole(hole_width, hole_height);
+}
+
 // ********************************************************************************************
 // The following modules are expected to be called by the user to create the desired container.
 
@@ -252,17 +272,28 @@ module gridfinity_single_square_bore(size, top_radius=0, bottom_radius=0, top_si
 //                          along the X and Y axes.
 //                          A "lid" for a container can be created by using just this module.
 // count - see Common Parameters above.
-// holes - Selects where to put magnet/screw holes. 0-none, 1-corners only, 2-everywhere
-//         Currently,
-module gridfinity_module_base(count, holes=0) {
+// holes - Selects where to put magnet/screw holes. 0-none, 1-corners only, 2-everywhere, 3-slide-in holes in corners
+// hole_width - Width of slide-in hole (only if holes==3)
+// hole_height - Height of slide-in hole (only if holes==3)
+// hole_offset - Height of the hole offset from the base (only if holes==3)
+module gridfinity_module_base(count, holes=0, hole_width, hole_height, hole_offset=0.2) {
     plane_height = module_unit_height - module_base_height;
-    for(x=[0:count.x-1]) {
-        for(y=[0:count.y-1]) {
-            translate([x * module_spacing, y*module_spacing])
-                gridfinity_insert(corners=determine_hole_corners(count, [x,y], holes));
+    // if holes==3, we're going to add the slide-in magnet holes as a difference overall
+    holes_ = holes == 3 ? 0 : holes;
+    difference() {
+        union() {
+            for(x=[0:count.x-1]) {
+                for(y=[0:count.y-1]) {
+                    translate([x * module_spacing, y*module_spacing])
+                        gridfinity_insert(corners=determine_hole_corners(count, [x,y], holes_));
+                }
+            }
+            gridfinity_module_mass(count, plane_height, module_base_height);
+        }
+        if(holes==3) {
+            translate([0,0,hole_offset]) gridfinity_magnet_holes(count, hole_width, hole_height);
         }
     }
-    gridfinity_module_mass(count, plane_height, module_base_height);
 }
 
 // gridfinity_internal_mass - creates a solid block bounded by the object's walls.

diff --git a/magnet_hole_tester.scad b/magnet_hole_tester.scad
@@ -0,0 +1,57 @@
+// Magnet Hole Tester for Gridfinity Module Generator
+// Copyright 2023 Chris Cogdon
+// Licence: CC-BY-SA-4.0 
+// https://www.github.com/chmarr/gridfinity-boxes
+//
+// Creates a model to test various sizes of holes for the Gridfinity-common 6x2mm magnet,
+// or magnets of any size by adjusting the parameters below. A "dot" is placed at the
+// first, or smallest, hole to ease orientation.
+
+// hole width for the middle hole. Typically the 'ideal' size.
+median_hole_width=6.0; // [2.0:0.1:10.0]
+
+// side difference between holes
+step_size=0.1; // [0.05:0.01:0.2]
+
+// number of holes. Should be an odd number so that the median_hole_width is the middle hole
+number_of_holes=7; // [3:2:15]
+
+// the height of the hole. Since we're intending to squeeze the sides, and that magnet heights are variable, this should be distinctly larger than the magnet height
+hole_height=2.2; // [1.0:0.1:5.2]
+
+// the height of the floor
+floor_height=0.4; // [0.1:0.05:1.0]
+
+/* [Advanced Options] */
+// object depth
+object_depth=6; // [5:1:15]
+
+// object height
+object_height=6; // [5:1:15]
+
+// inter-hole spacing
+interhole_spacing=5; // [2:1:10]
+
+module customizer_stop () {}
+epsilon=0.005;
+
+
+module hole_sampler() {
+    holes_to_either_side = (number_of_holes-1)/2;
+    first_hole = median_hole_width - holes_to_either_side * step_size;
+    object_width = median_hole_width * number_of_holes + interhole_spacing * (number_of_holes+1);
+
+    difference() {
+        cube([object_width, object_depth, object_height]);
+        translate([interhole_spacing, -epsilon, floor_height])
+            for(i=[0:number_of_holes-1]) {
+                hole_size=first_hole + i*step_size;
+                echo("Hole size:", hole_size)
+                translate([i*(median_hole_width + interhole_spacing),0,0])
+                    cube([hole_size, object_depth+2*epsilon, hole_height]);
+            }
+    translate([2,2,object_height-1+epsilon]) cylinder(h=1, d=1.5, $fn=40);
+    }
+}
+
+hole_sampler();
diff --git a/simple_box.scad b/simple_box.scad
@@ -23,16 +23,22 @@ internal_radius=10;
 // On which sides to place curves. [right, back, left, front].
 internal_radius_sides = [false, true, false, true];
 
-// Whether or not to insert holes at the bottom of the box. 0=no holes, 1=corners only, 2=everywhere.
+// Whether or not to insert holes at the bottom of the box. 0=no holes, 1=corners only, 2=everywhere, 3-slide-in holes in corners
 gridfinity_holes=0;
 
+// Width of slide-in magnet hole (only if gridfinity_holes==3)
+gridfinity_hole_width=5.9;
+
+// Height of slide-in magnet hole (only if gridfinity_holes==3)
+gridfinity_hole_height=2.2;
+
 // And now the fun stuff.
 module customizer_break(){}
 
 use <gridfinity_boxes.scad>
 $fn = 40;
 
-gridfinity_module_base(gridfinity_count, holes=gridfinity_holes);
+gridfinity_module_base(gridfinity_count, holes=gridfinity_holes, hole_width=gridfinity_hole_width, hole_height=gridfinity_hole_height);
 adjusted_box_height = add_stacking_lip ? ceil(box_height/7)*7 : box_height;
 gridfinity_wall(gridfinity_count, adjusted_box_height-7);
 gridfinity_internal_fillets(gridfinity_count, internal_radius, sides=internal_radius_sides);