diff --git a/nhf/touhou/yasaka_kanako/onbashira.py b/nhf/touhou/yasaka_kanako/onbashira.py
index f279562..afc8aa6 100644
--- a/nhf/touhou/yasaka_kanako/onbashira.py
+++ b/nhf/touhou/yasaka_kanako/onbashira.py
@@ -1,9 +1,10 @@
 from nhf.build import Model, TargetKind, target, assembly, submodel
 from nhf.materials import Role, Material
-import nhf.utils
 from nhf.parts.fasteners import FlatHeadBolt, HexNut, Washer
 from nhf.parts.electronics import ArduinoUnoR3, BatteryBox18650
+import nhf.utils
 
+import unittest
 from typing import Optional, Union
 import math
 from dataclasses import dataclass, field
@@ -2448,6 +2449,19 @@ class Onbashira(Model):
                 material=self.material_side,
                 role=Role.STRUCTURE | Role.DECORATION,
             )
+            for i in range(self.n_side):
+                name_bolt = f"chamber_back{i}boltFPI{i}"
+                a = a.addS(
+                    BOLT_COMMON.generate(),
+                    name=name_bolt,
+                    material=self.material_fastener,
+                    role=Role.CONNECTION,
+                )
+                a = a.constrain(
+                    f"chamber_back?holeF{i}",
+                    f"{name_bolt}?root",
+                    "Plane",
+                )
         if has_part(parts, "chamber_front"):
             a = a.addS(
                 self.chamber_front(),
@@ -2455,6 +2469,19 @@ class Onbashira(Model):
                 material=self.material_side,
                 role=Role.STRUCTURE | Role.DECORATION,
             )
+            for i in range(self.n_side):
+                name_bolt = f"chamber_front{i}boltFPI{i}"
+                a = a.addS(
+                    BOLT_COMMON.generate(),
+                    name=name_bolt,
+                    material=self.material_fastener,
+                    role=Role.CONNECTION,
+                )
+                a = a.constrain(
+                    f"chamber_front?holeF{i}",
+                    f"{name_bolt}?root",
+                    "Plane",
+                )
         if has_part(parts, "motor"):
             a = a.add(self.assembly_motor(), name="motor")
         if has_part(parts, "machine"):
@@ -2474,7 +2501,6 @@ class Onbashira(Model):
                 "Plane",
             )
 
-        # FIXME: Filter
         if has_part(parts, ["motor", "ring2"]):
             for i in range(self.n_side // 2):
                 j = self.n_side // 2 - 1 - i
@@ -2488,29 +2514,34 @@ class Onbashira(Model):
                 #    f"ring2/side{i*2+1}?holeStatorL",
                 #    "Plane",
                 #)
+
         if parts:
             return a.solve()
+
         for i in range(self.n_side):
             j = (i + 1) % self.n_side
             ir = (self.n_side - i) % self.n_side
 
-            coupler_name = f"stator_coupler{i}"
-            a = a.addS(
-                self.stator_coupler(),
-                name=coupler_name,
-                material=self.material_brace,
-                role=Role.STRUCTURE,
-            )
-            a = a.constrain(
-                f"{coupler_name}?holeOB",
-                f"ring1/side{i}?holeStatorR",
-                "Plane",
-            )
-            a = a.constrain(
-                f"{coupler_name}?holeIF",
-                f"machine/stator1?holeF{ir}",
-                "Plane",
-            )
+            if has_part(parts, "ring1") or has_part(parts, "machine"):
+                coupler_name = f"stator_coupler{i}"
+                a = a.addS(
+                    self.stator_coupler(),
+                    name=coupler_name,
+                    material=self.material_brace,
+                    role=Role.STRUCTURE,
+                )
+            if has_part(parts, "ring1"):
+                a = a.constrain(
+                    f"{coupler_name}?holeOB",
+                    f"ring1/side{i}?holeStatorR",
+                    "Plane",
+                )
+            if has_part(parts, "machine"):
+                a = a.constrain(
+                    f"{coupler_name}?holeIF",
+                    f"machine/stator1?holeF{ir}",
+                    "Plane",
+                )
 
             #name_bolt =f"stator_outer_bolt{i}"
             #a = a.addS(
@@ -2525,31 +2556,7 @@ class Onbashira(Model):
             #    "Plane",
             #)
 
-            name_bolt =f"chamber_back{i}boltFPI{i}"
-            a = a.addS(
-                BOLT_COMMON.generate(),
-                name=name_bolt,
-                material=self.material_fastener,
-                role=Role.CONNECTION,
-            )
-            a = a.constrain(
-                f"chamber_back?holeF{i}",
-                f"{name_bolt}?root",
-                "Plane",
-            )
 
-            name_bolt =f"chamber_front{i}boltFPI{i}"
-            a = a.addS(
-                BOLT_COMMON.generate(),
-                name=name_bolt,
-                material=self.material_fastener,
-                role=Role.CONNECTION,
-            )
-            a = a.constrain(
-                f"chamber_front?holeF{i}",
-                f"{name_bolt}?root",
-                "Plane",
-            )
             for ih in range(len(self.angle_joint_bolt_position)):
                 a = a.constrain(
                     f"chamber/side{i}?holeFPI{ih}",
@@ -2595,5 +2602,18 @@ class Onbashira(Model):
                             f"{nc}/side{i}?holeRSM{ih}",
                             "Plane",
                         )
- 
+
         return a.solve()
+
+
+class TestOnbashira(unittest.TestCase):
+
+    def test_collision(self):
+        from nhf.checks import pairwise_intersection
+
+        o = Onbashira()
+        a = o.assembly()
+        self.assertEqual(pairwise_intersection(a), [])
+
+if __name__ == '__main__':
+    unittest.main()