diff --git a/EXE_GdbModifySurf.cpp b/EXE_GdbModifySurf.cpp
index d9b4426..a3cf6a3 100644
--- a/EXE_GdbModifySurf.cpp
+++ b/EXE_GdbModifySurf.cpp
@@ -648,6 +648,41 @@ ExeCutSurfTmPlane( int nId, const Point3d& ptOn, const Vector3d& vtN, bool bSave
    return bOk ;
 }
 
+//-------------------------------------------------------------------------------
+bool
+ExeCutSurfBzPlane( int nId, const Point3d& ptOn, const Vector3d& vtN, bool bSaveOnEq, int nRefType)
+{
+   IGeomDB* pGeomDB = GetCurrGeomDB() ;
+   VERIFY_GEOMDB( pGeomDB, false)
+  // recupero la superficie TriMesh
+   ISurfBezier* pSbz = GetSurfBezier( pGeomDB->GetGeoObj( nId)) ;
+   bool bOk = ( pSbz != nullptr) ;
+  // recupero il riferimento locale
+   Frame3d frLoc ;
+   bOk = bOk && pGeomDB->GetGlobFrame( nId, frLoc) ;
+  // porto in locale il punto e la normale del piano
+   Point3d ptOnL = GetPointLocal( pGeomDB, ptOn, nRefType, frLoc) ;
+   Vector3d vtNL = GetVectorLocal( pGeomDB, vtN, nRefType, frLoc) ;
+  // calcolo il piano di taglio
+   Plane3d plPlane ;
+   bOk = bOk && plPlane.Set( ptOnL, vtNL) ;
+  // eseguo il taglio
+   bOk = bOk &&  pSbz->Cut( plPlane, bSaveOnEq) ;
+   ExeSetModified() ;
+  // se richiesto, salvo il comando Lua equivalente
+   if ( IsCmdLog()) {
+      string sLua = "EgtCutSurfBzPlane(" + IdToString( nId) + ",{" +
+                                           ToString( ptOn) + "},{" +
+                                           ToString( vtN) + "}," +
+                                           ( bSaveOnEq ? "true" : "false") + "," +
+                                           RefTypeToString( nRefType) + ")" +
+                    " -- Ok=" + ToString( bOk) ;
+      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
+   }
+  // restituisco risultato
+   return bOk ;
+}
+
 //-------------------------------------------------------------------------------
 bool
 ExeCutSurfTmClosedCurve( int nSurfId, int nCurveId, bool bSaveOnEq)
diff --git a/LUA_GdbModifySurf.cpp b/LUA_GdbModifySurf.cpp
index 5acf8d8..65ce029 100644
--- a/LUA_GdbModifySurf.cpp
+++ b/LUA_GdbModifySurf.cpp
@@ -283,6 +283,29 @@ LuaCutSurfTmPlane( lua_State* L)
    return 1 ;
 }
 
+//----------------------------------------------------------------------------
+static int
+LuaCutSurfBzPlane( lua_State* L)
+{
+  // 4 o 5 parametri : Id, ptOn, vtN, bSaveOnEq [, nRefType]
+   int nId ;
+   LuaCheckParam( L, 1, nId)
+   Point3d ptOn ;
+   LuaCheckParam( L, 2, ptOn)
+   Vector3d vtN ;
+   LuaCheckParam( L, 3, vtN)
+   bool bSaveOnEq ;
+   LuaGetParam( L, 4, bSaveOnEq) ;
+   int nRefType = RTY_DEFAULT ;
+   LuaGetParam( L, 5, nRefType) ;
+   LuaClearStack( L) ;
+  // taglio la superficie con ilpiano
+   bool bOk = ExeCutSurfBzPlane( nId, ptOn, vtN, bSaveOnEq, nRefType) ;
+  // restituisco il risultato
+   LuaSetParam( L, bOk) ;
+   return 1 ;
+}
+
 //----------------------------------------------------------------------------
 static int
 LuaCutSurfTmClosedCurve( lua_State* L)
@@ -481,6 +504,7 @@ LuaInstallGdbModifySurf( LuaMgr& luaMgr)
    bOk = bOk && luaMgr.RegisterFunction( "EgtSurfTmSwapFacets", LuaSurfTmSwapFacets) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtSurfTmRemovePart", LuaSurfTmRemovePart) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtCutSurfTmPlane", LuaCutSurfTmPlane) ;
+   bOk = bOk && luaMgr.RegisterFunction( "EgtCutSurfBzPlane", LuaCutSurfBzPlane) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtCutSurfTmClosedCurve", LuaCutSurfTmClosedCurve) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtSurfTmAdd", LuaSurfTmAdd) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtSurfTmSubtract", LuaSurfTmSubtract) ;