diff --git a/LuaLibs/MachiningLib.lua b/LuaLibs/MachiningLib.lua
index 33e88af..3c1692a 100644
--- a/LuaLibs/MachiningLib.lua
+++ b/LuaLibs/MachiningLib.lua
@@ -166,10 +166,16 @@ function MachiningLib.GetSplitMachinings( Machinings, SplittingPoints, Part )
          end
       -- anche le lavorazioni non splittate necessitano del segmento assegnato
       else
-         local dRightAddLength = dOriginalStartAddLength
-         local dLeftAddLength = dOriginalEndAddLength
-         if MachiningLib.StartsLeftSide( Machinings[i]) then
-            dRightAddLength, dLeftAddLength = dLeftAddLength, dRightAddLength
+         local dRightAddLength = 0
+         local dLeftAddLength = 0
+         -- si considerano allungamenti e accorciamenti solo se la feature è orientata principalmente lungo X
+         -- TODO il modo corretto è proiettare tutto, allungamenti e accorciamenti compresi, sulla faccia frontale
+         if abs( Machinings[i].vtToolDirection:getX()) < 0.707 then
+            dRightAddLength = dOriginalStartAddLength
+            dLeftAddLength = dOriginalEndAddLength
+            if MachiningLib.StartsLeftSide( Machinings[i]) then
+               dRightAddLength, dLeftAddLength = dLeftAddLength, dRightAddLength
+            end
          end
          for j = 1, nParts do
             local dNextSplitX = dEdgeMinX