diff --git a/bearing_bracket.py b/bearing_bracket.py
index 0829e58..2a99e93 100644
--- a/bearing_bracket.py
+++ b/bearing_bracket.py
@@ -1,5 +1,9 @@
 from build123d import *
 
+densa = 7800 / 1e6  # carbon steel density g/mm^3
+densb = 2700 / 1e6  # aluminum alloy
+densc = 1020 / 1e6  # ABS
+
 with BuildPart() as p:
     with BuildSketch() as s:
         Rectangle(115, 50)
@@ -7,5 +11,22 @@ with BuildPart() as p:
             SlotOverall(90, 12, mode=Mode.SUBTRACT)
     extrude(amount=15)
 
+    with BuildSketch(Plane.XZ.offset(50 / 2)) as s3:
+        with Locations((-115 / 2 + 26, 15)):
+            SlotOverall(42 + 2 * 26 + 12, 2 * 26, rotation=90)
+    zz = extrude(amount=-12)
+    split(bisect_by=Plane.XY)
+    edgs = p.part.edges().filter_by(Axis.Y).group_by(Axis.X)[-2]
+    fillet(edgs, 9)
 
 show_object(p)
+# debug(s3)
+# debug(edgs)
+
+
+# got_mass = p.part.volume*densa
+# want_mass = 797.15
+# tolerance = 1
+# delta = abs(got_mass - want_mass)
+# print(f"Mass: {got_mass:0.2f} g")
+# assert delta < tolerance, f'{got_mass=}, {want_mass=}, {delta=}, {tolerance=}'