mech: Add initial state

This code used to be developed outside a Git repository. It is moved
here to support the development workflow by frequent commits.

8 files changed, 199 insertions, 0 deletions

diff --git a/mech/Makefile b/mech/Makefile
new file mode 100644
index 0000000..1f80d35
--- /dev/null
+++ b/mech/Makefile
@@ -0,0 +1,19 @@
+PARTS := bottom top back front
+BUILD_DIR := ./build
+STL := $(PARTS:%=$(BUILD_DIR)/%.stl)
+GCODE := $(PARTS:%=$(BUILD_DIR)/%.gcode)
+
+.PHONY: all
+all: $(GCODE)
+
+$(BUILD_DIR)/%.gcode: $(BUILD_DIR)/%.stl
+	mkdir -p $(dir $@)
+	prusa-slicer --output $@ --export-gcode $<
+
+$(BUILD_DIR)/%.stl: %.scad
+	mkdir -p $(dir $@)
+	openscad --export-format binstl -o $@ $<
+
+.PHONY: clean
+clean:
+	rm -rf $(BUILD_DIR)
diff --git a/mech/assembly.scad b/mech/assembly.scad
new file mode 100644
index 0000000..3df96c8
--- /dev/null
+++ b/mech/assembly.scad
@@ -0,0 +1,13 @@
+use <bottom.scad>
+use <top.scad>
+use <back.scad>
+use <front.scad>
+
+module assembly() {
+	bottom();
+//	top();
+	back();
+//	front();
+}
+
+assembly();
diff --git a/mech/back.scad b/mech/back.scad
new file mode 100644
index 0000000..16f6c2e
--- /dev/null
+++ b/mech/back.scad
@@ -0,0 +1,7 @@
+include <common.scad>
+
+module back() {
+	pcb_case_panel_back(dim, t);
+}
+
+rotate([0,90,0]) back();
diff --git a/mech/bottom.scad b/mech/bottom.scad
new file mode 100644
index 0000000..cac355e
--- /dev/null
+++ b/mech/bottom.scad
@@ -0,0 +1,16 @@
+include <common.scad>
+
+module bottom() {
+	union () {
+		pcb_case_shell_bottom(
+			dim, t, h, [
+				base_socket,
+				base_socket + dx,
+				base_socket + dy,
+				base_socket + dx + dy
+			]
+		);
+	}
+}
+
+bottom();
diff --git a/mech/common.scad b/mech/common.scad
new file mode 100644
index 0000000..c433447
--- /dev/null
+++ b/mech/common.scad
@@ -0,0 +1,16 @@
+use <pcb_case.scad>
+
+$fa = 12;          // default is 12
+$fs = 0.5;         // default is 2
+
+t = 2;
+tol = 1;
+base_socket = [3/2+2.3+2*t+tol,3/2+2.1+2.7+t+tol];
+dx = [28.9,0];
+dy = [0,58.1];
+dim = [
+	base_socket[0] + dx[0] + 3/2 + 4 + 2*t + tol,
+	base_socket[1] + dy[1] + 3/2 + 2 + 0.9 + 6 + t + tol,
+	39   // TODO
+];
+h = 10;  // TODO
diff --git a/mech/front.scad b/mech/front.scad
new file mode 100644
index 0000000..e35c146
--- /dev/null
+++ b/mech/front.scad
@@ -0,0 +1,7 @@
+include <common.scad>
+
+module front() {
+	pcb_case_panel_front(dim, t);
+}
+
+rotate([0,90,0]) front();
diff --git a/mech/pcb_case.scad b/mech/pcb_case.scad
new file mode 100644
index 0000000..bbfe9bc
--- /dev/null
+++ b/mech/pcb_case.scad
@@ -0,0 +1,112 @@
+// A generic parametric PCB case
+
+nut_h = 3;
+nut_d = 4.15;
+nut_r = nut_d / 2;
+bolt_d = 3;
+bolt_r = bolt_d / 2;
+
+module rounded_cube(dim, radius) {
+	range_y = [radius, dim[1]-radius];
+	range_z = [radius, dim[2]-radius];
+	height = dim[0];
+
+	hull() {
+		for (y=range_y, z=range_z) {
+			translate([0,y,z]) rotate([0,90,0]) cylinder(r=radius, h=height);
+		}
+	}
+}
+
+module shell_base(dim, t) {
+	radius = t;
+	difference() {
+		rounded_cube(dim, radius);
+		translate([0,0,dim[2]/2])
+			cube([dim[0], dim[1], dim[2]/2]);
+		translate([3*t, t, t])
+			rounded_cube([dim[0]-6*t, dim[1]-2*t, dim[2]-2*t], radius);
+		translate([0, 2*t, 2*t])
+			rounded_cube([dim[0], dim[1]-4*t, dim[2]-4*t], radius);
+		for (x_off = [t, dim[0]-2*t]) {
+			translate([x_off, t, t])
+				rounded_cube([t, dim[1]-2*t, dim[2]-2*t], radius);
+		}
+		for (x = [dim[0]/4, dim[0]-dim[0]/4]) {
+			translate([x,0,dim[2]/2-1.5*bolt_d])
+				rotate([-90,0,0])
+					cylinder(r=bolt_r, h=1.1*t);
+		}
+	}
+}
+
+module shell_connector(dim, t) {
+	size_x = dim[0]-6*t;
+	size_y = 2*nut_h;
+	size_z = dim[2]/2+3*bolt_d;
+
+	difference () {
+		// base body
+		translate([3*t,dim[1]-t-size_y,0])
+			cube([size_x,size_y,size_z]);
+
+		// bolt holes
+		for (x = [dim[0]/4, dim[0]-dim[0]/4]) {
+			translate([x,dim[1]-t,dim[2]/2+1.5*bolt_d])
+				rotate([90,0,0])
+					cylinder(r=bolt_r, h=size_y);
+		}
+
+		// nut holes
+		for (x = [dim[0]/4, dim[0]-dim[0]/4]) {
+			translate([x,dim[1]-t-size_y,dim[2]/2+1.5*bolt_d])
+				rotate([-90,0,0])
+					cylinder(r=nut_r, h=nut_h);
+		}
+	}
+
+	echo(min_shell_bolt_length=t+size_y);
+}
+
+module pcb_case_shell(dim, t, h, sockets) {
+	difference () {
+		union() {
+			shell_base(dim, t);
+			shell_connector(dim, t);
+			for (socket = [0:len(sockets)-1]) {
+				translate([sockets[socket][0], sockets[socket][1], 0])
+					cylinder(d=nut_d+2, h=h);
+			}
+		}
+		for (socket = [0:len(sockets)-1]) {
+			translate([sockets[socket][0], sockets[socket][1], 0]) {
+				cylinder(d=bolt_d, h=h);
+				cylinder(d=0.9*nut_d, h=nut_h);
+			}
+		}
+	}
+}
+
+module pcb_case_shell_bottom(dim, t, h, sockets) {
+	pcb_case_shell(dim, t, h, sockets);
+}
+
+module pcb_case_shell_top(dim, t) {
+	translate([0,dim[1],dim[2]])
+		rotate([180,0,0])
+			pcb_case_shell(dim, t, 0, []);
+}
+
+module pcb_case_panel(dim, t) {
+	rounded_cube([t,dim[1]-2*t,dim[2]-2*t], t);
+}
+
+module pcb_case_panel_back(dim, t) {
+	translate([t,t,t])
+		pcb_case_panel(dim, t);
+}
+
+module pcb_case_panel_front(dim, t) {
+	translate([dim[0]-2*t,t,t])
+		pcb_case_panel(dim, t);
+}
diff --git a/mech/top.scad b/mech/top.scad
new file mode 100644
index 0000000..55882f0
--- /dev/null
+++ b/mech/top.scad
@@ -0,0 +1,9 @@
+include <common.scad>
+
+module top() {
+	difference() {
+		pcb_case_shell_top(dim, t);
+	}
+}
+
+rotate([180,0,0]) top();