diff --git a/src/core.py b/src/core.py
index 10d302a..ffcfe43 100644
--- a/src/core.py
+++ b/src/core.py
@@ -15,7 +15,7 @@
 # Prepare the stem_wrapper
 with BuildPart() as stem_wrapper:
     with BuildSketch(Plane.front):  # as cross_section
-        RectangleRounded(stem_width + 2 * wall, stem_height + 2 * wall, wall)
+        RectangleRounded(stem_width + 2 * wall, stem_height + 2 * wall, wall/2 - eps)
         RectangleRounded(stem_width, stem_height, stem_fillet - wall, mode=Mode.SUBTRACT)
     extrude(amount=stem_length/2, both=True)
     fillet(faces().filter_by(Plane.XY).edges(), wall/2 - eps)
@@ -25,7 +25,7 @@
 # Prepare the screw hole adapter
 screw_hole_base = ScrewableCylinder()
 bb = screw_hole_base.bounding_box()
-eps_offset_loft = 0.01
+eps_offset_loft = 0.1  # Causes broken geometry if too small
 RigidJoint("left", screw_hole_base, Location((bb.min.X - eps_offset_loft, bb.center().Y, bb.center().Z), (0, 90, 0)))
 
 with BuildPart() as core:
@@ -46,24 +46,27 @@
     del loft_screw_hole_face, loft_stem_face, screw_hole_base
 
     # Make it 3D printable by adding top and bottom supports
-    for face_side in [-1, 1]:  # Top and bottom
-        face = faces().group_by(Axis.Z)[0 if face_side < 0 else -1].face()
+    for face_side in [-1, 1]:  # Bottom and top
+        face_search = 0 if face_side < 0 else -1
+        face = faces().group_by(Axis.Z)[face_search].face()
         extreme = stem_wrapper.bounding_box().min if face_side < 0 else stem_wrapper.bounding_box().max
-        extreme.Z += face_side * -(wall - eps_offset_loft*10)  # Ignore fillet
+        extreme.Z -= face_side * wall/2  # Ignore fillet
         max_extrude = face.center().Z - extreme.Z
         extrude(face, amount=abs(max_extrude))
         assert core.part.is_valid()
         del extreme
         # Prepare a cut plane
         max_offset = face.bounding_box().size.X
-        cut_plane_angle = degrees(atan2(max_offset, max_extrude))
+        cut_plane_angle = degrees(atan2(max_extrude, max_offset))
         print(cut_plane_angle)
         bb = face.bounding_box()
         cut_plane = Plane(Location((bb.max.X, bb.center().Y, bb.center().Z), (0, -cut_plane_angle, 0)))
-        split(bisect_by=cut_plane, keep=Keep.TOP)
+        split(bisect_by=cut_plane, keep=Keep.TOP if face_side < 0 else Keep.BOTTOM)
         assert core.part.is_valid()
         assert len(core.part.solids()) == 1
         del face, cut_plane
+        # Fillet some edges of supports
+        fillet(faces().group_by(Axis.Z)[face_search].edges() - edges().group_by(Axis.X)[0], wall/2.01)
 
     # Mirror to the other side
     mirror(about=Plane.YZ)
diff --git a/src/screwable_cylinder.py b/src/screwable_cylinder.py
index 13bb1f1..c070789 100644
--- a/src/screwable_cylinder.py
+++ b/src/screwable_cylinder.py
@@ -10,7 +10,7 @@
 
 @dataclass(kw_only=True)
 class ScrewableCylinder(BasePartObject):
-    screw_length: float = 8
+    screw_length: float = 12
     screw_diameter: float = 5  # M5
     screw_head_diameter: float = 8.5  # M5
     screw_head_height: float = 5  # M5