diff --git a/Cad/BlockRawFreeForgeRoundHeadDrawer.cs b/Cad/BlockRawFreeForgeRoundHeadDrawer.cs
index 24b0401..bb8efd1 100644
--- a/Cad/BlockRawFreeForgeRoundHeadDrawer.cs
+++ b/Cad/BlockRawFreeForgeRoundHeadDrawer.cs
@@ -311,29 +311,45 @@ namespace CadParamPluging.Cad
                 double H = height;
                 double r = innerFilletR;
                 
-                double xCurrentLeft = ox + arcHeight + r;
-                double xCurrentRight = ox + totalWidth - arcHeight - r;
-
-                double sagitta = arcHeight + r;
-                double halfChord = H / 2.0;
+                // Calculate geometric bounds
+                double xInnerLeft = ox + arcHeight;
+                double xInnerRight = ox + totalWidth - arcHeight;
                 
-                double bulge = 0;
-                if (halfChord > 1e-3)
-                {
-                    bulge = -(sagitta / halfChord);
-                }
+                double yBottomStraight = oy + r;
+                double yTopStraight = oy + H - r;
+                
+                double chordLength = H - 2.0 * r;
+                if (chordLength < 0.1) return; // Should not happen for reasonable params
 
-                var poly = new Polyline();
+                double sagitta = arcHeight;
+                
+                // Bulge calculation: bulge = 2 * sagitta / chord
+                // For a CCW arc, bulge is positive.
+                double bulge = (2.0 * sagitta) / chordLength;
 
-                poly.AddVertexAt(0, new Point2d(xCurrentRight, oy), 0, 0, 0);
-                poly.AddVertexAt(1, new Point2d(xCurrentLeft, oy), bulge, 0, 0);
-                poly.AddVertexAt(2, new Point2d(xCurrentLeft, oy + H), 0, 0, 0);
-                poly.AddVertexAt(3, new Point2d(xCurrentRight, oy + H), bulge, 0, 0);
-                poly.Closed = true;
+                // Left Arc: From Top to Bottom, bulging Left (CCW)
+                // Start: (xInnerLeft, yTopStraight)
+                // End: (xInnerLeft, yBottomStraight)
+                // Path: 12 o'clock -> 9 o'clock -> 6 o'clock direction is CCW.
+                var leftPoly = new Polyline();
+                leftPoly.AddVertexAt(0, new Point2d(xInnerLeft, yTopStraight), bulge, 0, 0);
+                leftPoly.AddVertexAt(1, new Point2d(xInnerLeft, yBottomStraight), 0, 0, 0);
+                
+                ctx.Style?.Apply(leftPoly, DrawingStyleManager.Role.OutlineBold);
+                ctx.Btr.AppendEntity(leftPoly);
+                ctx.Tr.AddNewlyCreatedDBObject(leftPoly, true);
 
-                ctx.Style?.Apply(poly, DrawingStyleManager.Role.OutlineBold);
-                ctx.Btr.AppendEntity(poly);
-                ctx.Tr.AddNewlyCreatedDBObject(poly, true);
+                // Right Arc: From Bottom to Top, bulging Right (CCW)
+                // Start: (xInnerRight, yBottomStraight)
+                // End: (xInnerRight, yTopStraight)
+                // Path: 6 o'clock -> 3 o'clock -> 12 o'clock direction is CCW.
+                var rightPoly = new Polyline();
+                rightPoly.AddVertexAt(0, new Point2d(xInnerRight, yBottomStraight), bulge, 0, 0);
+                rightPoly.AddVertexAt(1, new Point2d(xInnerRight, yTopStraight), 0, 0, 0);
+
+                ctx.Style?.Apply(rightPoly, DrawingStyleManager.Role.OutlineBold);
+                ctx.Btr.AppendEntity(rightPoly);
+                ctx.Tr.AddNewlyCreatedDBObject(rightPoly, true);
             }
             catch { }
         }