diff --git a/Cad/ShaftRawFreeForgeSquareShaftDrawer.cs b/Cad/ShaftRawFreeForgeSquareShaftDrawer.cs
index efdbfcd..3d0ef8a 100644
--- a/Cad/ShaftRawFreeForgeSquareShaftDrawer.cs
+++ b/Cad/ShaftRawFreeForgeSquareShaftDrawer.cs
@@ -429,13 +429,17 @@ namespace CadParamPluging.Cad
                 
                 if (sectionW > 0)
                 {
+                    double secR = r;
+                    double maxR = Math.Min(sectionW / 2.0, H / 2.0);
+                    if (secR > maxR) secR = maxR;
+
                     var newSegs = new List<Tuple<double, double>>();
                     foreach(var seg in segments)
                     {
                         if (sectionOx > seg.Item1 && (sectionOx + sectionW) < seg.Item2)
                         {
-                            newSegs.Add(Tuple.Create(seg.Item1, sectionOx));
-                            newSegs.Add(Tuple.Create(sectionOx + sectionW, seg.Item2));
+                            newSegs.Add(Tuple.Create(seg.Item1, sectionOx + secR));
+                            newSegs.Add(Tuple.Create(sectionOx + sectionW - secR, seg.Item2));
                         }
                         else newSegs.Add(seg);
                     }