diff --git a/cad/build.py b/cad/build.py
index 6bb3de7..296b6c4 100644
--- a/cad/build.py
+++ b/cad/build.py
@@ -68,7 +68,6 @@ def build_drive_shaft_mount():
                 mirror(profile.line, Plane.YZ)
             make_face()
 
-            # TODO: add a seem channel
             with Locations((0, bearing_offset)):
                 Circle(bearing_through_hole_diameter / 2, mode=Mode.SUBTRACT)
 
@@ -76,9 +75,12 @@ def build_drive_shaft_mount():
         mirror(about=Plane.XY)
 
         with Locations((0, bearing_offset, drive_shaft_mount.faces().sort_by(Axis.Z)[-1].center().Z)):
-            # TODO: add a seem channel
-            Hole(bearing_diameter / 2, (thickness / 2) + (bearing_height / 2))
             Hole(shaft_clearance_diameter / 2, (thickness / 2) - (bearing_height / 2))
+            Hole(bearing_diameter / 2, (thickness / 2) + (bearing_height / 2))
+            # this is a seem channel
+            with BuildSketch(Location((0, bearing_offset + bearing_diameter / 2, drive_shaft_mount.faces().sort_by(Axis.Z)[-1].center().Z))):
+                Triangle(A=90, b=1, c=1)
+            extrude(amount=-((thickness / 2) + (bearing_height / 2)), mode=Mode.SUBTRACT)
 
         Box(core_width + (screw_blocks_width * 2), track_width, track_height, (90, 0, 0), (Align.CENTER, Align.CENTER, Align.MIN))