diff --git a/cad/build.py b/cad/build.py
index 5805612..a05dd84 100644
--- a/cad/build.py
+++ b/cad/build.py
@@ -106,7 +106,7 @@ def build_drive_shaft_bar_adapter():
     shaft_hub_screw_head_diam = 7
 
     with BuildPart() as drive_shaft_bar_adapter:
-        Box(ext_size + (thickness * 2), ext_size + (thickness * 2), height, align=(Align.CENTER, Align.CENTER, Align.MIN))
+        Cylinder((ext_size / 2) + thickness, height, align=(Align.CENTER, Align.CENTER, Align.MIN))
 
         # hollow the box
         with Locations((0, 0, thickness)):