wip

Author: greg19

freecad/gridfinity_workbench/const.py

@@ -18,7 +18,7 @@
 
 MAGNET_HOLE_DISTANCE_FROM_EDGE = 8
 
-HOLE_SHAPES = ["Round", "Hex"]
+HOLE_SHAPES = ["Round", "Crush ribs", "Hex"]
 
 ## Bins
 # General Bin Parameters

freecad/gridfinity_workbench/magnet_hole.py

@@ -10,6 +10,55 @@
 from . import utils
 
 
+def _crush_ribs(
+    radius: fc.Units.Quantity,
+    depth: fc.Units.Quantity,
+    *,
+    n: int,
+    beta: float,
+) -> Part.Shape:
+    """Make crush ribs inner shape.
+
+    Args:
+        radius (fc.Units.Quantity): Inner radius.
+        depth (fc.Units.Quantity): Depth.
+        n (int): Number of ribs.
+        beta (float): Waviness of the ribs. It is the angle at wich inner at outer arcs meet.
+        A value of 0 would result in a perfect circle.
+
+    """
+    alpha = math.pi / n / 2
+
+    def get_midpoint(beta: float) -> float:
+        return (math.sin(beta) - math.sin(alpha)) / math.sin(beta - alpha)
+
+    r1 = radius.Value
+    r2 = radius.Value / get_midpoint(beta)
+    r3 = r2 * get_midpoint(-beta)
+
+    p1 = fc.Vector(r2, 0)
+    p2 = fc.Vector(r2 * math.cos(2 * alpha), r2 * math.sin(2 * alpha))
+    q = r1 * fc.Vector(math.cos(alpha), math.sin(alpha))
+    r = r3 * fc.Vector(math.cos(alpha), math.sin(alpha))
+
+    lines = []
+    for _ in range(n):
+        lines.append(Part.Arc(p1, q, p2))
+        lines.append(Part.Arc(p1, r, p2))
+    for i, arc in enumerate(lines):
+        placement = fc.Placement(
+            fc.Vector(0, 0, 0),
+            fc.Vector(0, 0, 1),
+            math.degrees((i + 0.5) / len(lines) * 2 * math.pi),
+        )
+        arc.rotate(placement)
+    wire = utils.curve_to_wire(lines)
+    face = Part.Face(wire)
+    shape = face.extrude(fc.Vector(0, 0, depth))
+
+    return shape
+
+
 def _hex_shape(radius: fc.Units.Quantity, depth: fc.Units.Quantity) -> Part.Shape:
     # Ratio of 2/sqrt(3) converts from inscribed circle radius to circumscribed
     # circle radius
@@ -37,6 +86,8 @@ def from_obj(obj: fc.DocumentObject) -> Part.Shape:
 
     if hole_shape == "Hex":
         shape = _hex_shape(radius, depth)
+    elif hole_shape == "Crush ribs":
+        shape = _crush_ribs(radius, depth, n=8, beta=0.5 * math.pi / 2)
     elif hole_shape == "Round":
         shape = Part.makeCylinder(radius, depth)
         if obj.Baseplate:
@@ -48,7 +99,6 @@ def from_obj(obj: fc.DocumentObject) -> Part.Shape:
                 pPnt=fc.Vector(0, 0, depth - chamfer),
             )
             shape = shape.fuse(chamfer_shape)
-        return shape
     else:
         raise ValueError(f"Unrecognised magnet hole shape {hole_shape:!r}")
 
@@ -59,10 +109,11 @@ def relief(obj: fc.DocumentObject) -> Part.Shape:
     """Create a magnet relief shape for four magnets from object properties."""
     x_hole_pos = obj.xGridSize / 2 - obj.MagnetHoleDistanceFromEdge
     y_hole_pos = obj.yGridSize / 2 - obj.MagnetHoleDistanceFromEdge
+    alpha = math.pi / 8
 
     r = obj.MagnetHoleDiameter / 2
-    x1 = r * math.cos(math.pi / 8)
-    y1 = r * math.sin(math.pi / 8)
+    x1 = r * math.cos(alpha)
+    y1 = r * math.sin(alpha)
     p1 = fc.Vector(x1, y1)
     p2 = fc.Vector(x1 + 2 * y1, y1)
     p3 = fc.Vector(x1 + 3 * y1, 0)