diff --git a/nhf/materials.py b/nhf/materials.py
index a95a7eb..2f96bda 100644
--- a/nhf/materials.py
+++ b/nhf/materials.py
@@ -21,7 +21,7 @@ class Role(Enum):
     STRUCTURE = _color('gray', 0.4)
     DECORATION = _color('lightseagreen', 0.4)
     ELECTRONIC = _color('mediumorchid', 0.5)
-    MARKER = _color('white', 1.0)
+    MARKER = _color('cyan', 1.0)
 
     def __init__(self, color: Cq.Color):
         self.color = color
diff --git a/nhf/touhou/houjuu_nue/__init__.py b/nhf/touhou/houjuu_nue/__init__.py
index 7cdba60..a514bd8 100644
--- a/nhf/touhou/houjuu_nue/__init__.py
+++ b/nhf/touhou/houjuu_nue/__init__.py
@@ -599,7 +599,9 @@ class Parameters(Model):
                            "s2/elbow_top_spacer?conn1",
                            "Plane")
             )
-        return result.solve()
+        if len(parts) > 1:
+            result.solve()
+        return result
 
     @assembly()
     def wings_assembly(self) -> Cq.Assembly:
diff --git a/nhf/touhou/houjuu_nue/joints.py b/nhf/touhou/houjuu_nue/joints.py
index 6e653af..a2f85a3 100644
--- a/nhf/touhou/houjuu_nue/joints.py
+++ b/nhf/touhou/houjuu_nue/joints.py
@@ -262,7 +262,7 @@ class Beam:
             .add(self.foot(), name="top",
                  loc=Cq.Location((0, h, 0)))
             .add(self.foot(), name="bot",
-                 loc=Cq.Location((0, -h, 0), (0, 0, 1), 180))
+                 loc=Cq.Location((0, -h, 0), (1, 0, 0), 180))
         )
         return result
 
@@ -424,7 +424,10 @@ class DiskJoint(Model):
             ))
         )
         result.faces(">Z").tag("mate")
-        result.faces(">Z").workplane().tagPlane("dir", direction="+X")
+        result.faces(">Z").workplane().tagPlane("dirX", direction="+X")
+        # two directional vectors are required to make the angle constrain
+        # unambiguous
+        result.faces(">Z").workplane().tagPlane("dirY", direction="+Y")
         result = result.cut(
             self
             .wall()
@@ -486,17 +489,15 @@ class DiskJoint(Model):
                         housing_lower: str,
                         housing_upper: str,
                         disk: str,
-                        angle: Tuple[float, float, float] = (0, 0, 0),
+                        angle: float,
                         ) -> Cq.Assembly:
-        """
-        The angle supplied must be perpendicular to the disk normal.
-        """
         (
             assembly
             .constrain(f"{disk}?mate_bot", f"{housing_lower}?mate", "Plane")
             .constrain(f"{disk}?mate_top", f"{housing_upper}?mate", "Plane")
-            .constrain(f"{housing_lower}?dir", f"{housing_upper}?dir", "Axis")
-            .constrain(f"{disk}?dir", "FixedRotation", angle)
+            .constrain(f"{housing_lower}?dirX", f"{housing_upper}?dir", "Axis")
+            .constrain(f"{housing_lower}?dirX", f"{disk}?dir", "Axis", param=angle)
+            .constrain(f"{housing_lower}?dirY", f"{disk}?dir", "Axis", param=angle - 90)
         )
 
 
@@ -519,7 +520,7 @@ class DiskJoint(Model):
             housing_lower="housing_lower",
             housing_upper="housing_upper",
             disk="disk",
-            angle=(0, 0, angle),
+            angle=angle,
         )
         return result.solve()
 
@@ -567,10 +568,16 @@ class ElbowJoint:
     def child_joint(self) -> Cq.Assembly:
         angle = -self.disk_joint.tongue_span / 2
         dz = self.disk_joint.disk_thickness / 2
+        # We need to ensure the disk is on the "other" side so
+        flip = Cq.Location((0, 0, 0), (0, 0, 1), 180)
         result = (
             self.child_beam.beam()
             .add(self.disk_joint.disk(), name="disk",
-                 loc=Cq.Location((-self.child_arm_radius, 0, -dz), (0, 0, 1), angle))
+                 loc=flip * Cq.Location((-self.child_arm_radius, 0, -dz), (0, 0, 1), angle))
+            .constrain("disk", "Fixed")
+            .constrain("top", "Fixed")
+            .constrain("bot", "Fixed")
+            .solve()
         )
         return result
 
@@ -600,24 +607,27 @@ class ElbowJoint:
                  loc=axial_offset * Cq.Location((0, 0, housing_dz)))
             .add(connector, name="connector",
                  loc=axial_offset)
+            .constrain("housing", "Fixed")
+            .constrain("connector", "Fixed")
+            .solve()
         )
         return result
 
     def assembly(self, angle: float = 0) -> Cq.Assembly:
-        da = self.disk_joint.tongue_span / 2
+        da = self.disk_joint.tongue_span / 2 + 180
         result = (
             Cq.Assembly()
             .add(self.child_joint(), name="child", color=Role.CHILD.color)
             .add(self.parent_joint_lower(), name="parent_lower", color=Role.CASING.color)
             .add(self.parent_joint_upper(), name="parent_upper", color=Role.PARENT.color)
-            .constrain("parent_lower", "Fixed")
+            #.constrain("parent_lower", "Fixed")
         )
         self.disk_joint.add_constraints(
             result,
             housing_lower="parent_lower",
             housing_upper="parent_upper/housing",
             disk="child/disk",
-            angle=(0, 0, angle + da),
+            angle=angle,
         )
         return result.solve()
 
diff --git a/nhf/utils.py b/nhf/utils.py
index f75c8ec..a834022 100644
--- a/nhf/utils.py
+++ b/nhf/utils.py
@@ -70,6 +70,9 @@ def make_arrow(size: float = 2) -> Cq.Workplane:
     result.faces("<Z").tag("dir_rev")
     return result
 
+def to_marker_name(tag: str) -> str:
+    return tag.replace("?", "__T").replace("/", "__Z") + "_marker"
+
 def mark_point(self: Cq.Assembly,
                tag: str,
                size: float = 2,
@@ -77,7 +80,7 @@ def mark_point(self: Cq.Assembly,
     """
     Adds a marker to make a point visible
     """
-    name = f"{tag}_marker"
+    name = to_marker_name(tag)
     return (
         self
         .add(make_sphere(size), name=name, color=color)
@@ -93,7 +96,7 @@ def mark_plane(self: Cq.Assembly,
     """
     Adds a marker to make a plane visible
     """
-    name = tag.replace("?", "__") + "_marker"
+    name = to_marker_name(tag)
     return (
         self
         .add(make_arrow(size), name=name, color=color)