diff --git a/EXE_GdbModifySurf.cpp b/EXE_GdbModifySurf.cpp
index e9bae67..54215d0 100644
--- a/EXE_GdbModifySurf.cpp
+++ b/EXE_GdbModifySurf.cpp
@@ -186,7 +186,7 @@ ExeSurfFrAdd( int nId1, int nId2)
    const ISurfFlatRegion* pSfr2L = pSfr2 ;
    PtrOwner<ISurfFlatRegion>pTmp ;
    if ( ! AreSameFrame( frSurf1, frSurf2)) {
-      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      pTmp.Set( pSfr2->Clone()) ;
       bOk = bOk && ! IsNull( pTmp) ;
       bOk = bOk && pTmp->LocToLoc( frSurf2, frSurf1) ;
       pSfr2L = pTmp ;
@@ -226,7 +226,7 @@ ExeSurfFrSubtract( int nId1, int nId2)
    const ISurfFlatRegion* pSfr2L = pSfr2 ;
    PtrOwner<ISurfFlatRegion>pTmp ;
    if ( ! AreSameFrame( frSurf1, frSurf2)) {
-      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      pTmp.Set( pSfr2->Clone()) ;
       bOk = bOk && ! IsNull( pTmp) ;
       bOk = bOk && pTmp->LocToLoc( frSurf2, frSurf1) ;
       pSfr2L = pTmp ;
@@ -269,7 +269,7 @@ ExeSurfFrIntersect( int nId1, int nId2)
    const ISurfFlatRegion* pSfr2L = pSfr2 ;
    PtrOwner<ISurfFlatRegion>pTmp ;
    if ( ! AreSameFrame( frSurf1, frSurf2)) {
-      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      pTmp.Set( pSfr2->Clone()) ;
       bOk = bOk && ! IsNull( pTmp) ;
       bOk = bOk && pTmp->LocToLoc( frSurf2, frSurf1) ;
       pSfr2L = pTmp ;
@@ -390,7 +390,7 @@ ExeSurfFrMoveSimpleNoCollision( int nId1, int nId2, const Vector3d& vtDir, doubl
    const ISurfFlatRegion* pSfr2L = pSfr2 ;
    PtrOwner<ISurfFlatRegion>pTmp ;
    if ( ! AreSameFrame( frSurf1, frSurf2)) {
-      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      pTmp.Set( pSfr2->Clone()) ;
       bOk = bOk && ! IsNull( pTmp) ;
       bOk = bOk && pTmp->LocToLoc( frSurf2, frSurf1) ;
       pSfr2L = pTmp ;
@@ -423,7 +423,7 @@ ExeSurfFrRotateSimpleNoCollision( int nId1, int nId2, const Point3d& ptCen, doub
    const ISurfFlatRegion* pSfr2L = pSfr2 ;
    PtrOwner<ISurfFlatRegion>pTmp ;
    if ( ! AreSameFrame( frSurf1, frSurf2)) {
-      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      pTmp.Set( pSfr2->Clone()) ;
       bOk = bOk && ! IsNull( pTmp) ;
       bOk = bOk && pTmp->LocToLoc( frSurf2, frSurf1) ;
       pSfr2L = pTmp ;
@@ -639,3 +639,37 @@ ExeCopySurfTmFacet( int nId, int nFacet, int nDestGrpId)
    }
    return nFacId ;
 }
+
+//-------------------------------------------------------------------------------
+bool
+ExeCutSurfTm( int nId, const Point3d& ptOn, const Vector3d& vtN, bool bSaveOnEq, int nRefType)
+{
+   IGeomDB* pGeomDB = GetCurrGeomDB() ;
+   VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
+  // recupero la superficie TriMesh
+   ISurfTriMesh* pStm = GetSurfTriMesh( pGeomDB->GetGeoObj( nId)) ;
+   bool bOk = ( pStm != 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 && SetPlane( ptOnL, vtNL, plPlane) ;
+  // eseguo il taglio
+   bOk = bOk &&  pStm->Cut( plPlane, bSaveOnEq) ;
+   ExeSetModified() ;
+  // se richiesto, salvo il comando Lua equivalente
+   if ( IsCmdLog()) {
+      string sLua = "EgtCutSurfTm(" + ToString( nId) + ",{" +
+                                      ToString( ptOn) + "},{" +
+                                      ToString( vtN) + "}," +
+                                      RefTypeToString( nRefType) + ")" +
+                    " -- Ok=" + ToString( bOk) ;
+      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
+   }
+  // restituisco risultato
+   return bOk ;
+}
diff --git a/EXE_GeoSnap.cpp b/EXE_GeoSnap.cpp
index 5562352..200ffb9 100644
--- a/EXE_GeoSnap.cpp
+++ b/EXE_GeoSnap.cpp
@@ -955,7 +955,7 @@ ExeSurfFrChunkSimpleClassify( int nId1, int nChunk1, int nId2, int nChunk2)
    const ISurfFlatRegion* pSfr2L = pSfr2 ;
    PtrOwner<ISurfFlatRegion> pTmp ;
    if ( ! AreSameFrame( frSurf1, frSurf2)) {
-      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      pTmp.Set( pSfr2->Clone()) ;
       bOk = bOk && ! IsNull( pTmp) ;
       bOk = bOk && pTmp->LocToLoc( frSurf2, frSurf1) ;
       pSfr2L = pTmp ;
diff --git a/EXE_NstPartNesting.cpp b/EXE_NstPartNesting.cpp
index 62d985d..aa63f90 100644
--- a/EXE_NstPartNesting.cpp
+++ b/EXE_NstPartNesting.cpp
@@ -1178,7 +1178,7 @@ MySurfFrMoveSimpleNoCollision( int nId1, int nId2, const Vector3d& vtDir, double
    const ISurfFlatRegion* pSfr2L = pSfr2 ;
    PtrOwner<ISurfFlatRegion> pTmp ;
    if ( ! AreSameFrame( frSurf1, frSurf2)) {
-      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      pTmp.Set( pSfr2->Clone()) ;
       bOk = bOk && ! IsNull( pTmp) ;
       bOk = bOk && pTmp->LocToLoc( frSurf2, frSurf1) ;
       pSfr2L = pTmp ;
diff --git a/EgtExecutor.rc b/EgtExecutor.rc
index eb5448d..f4c0b6b 100644
Binary files a/EgtExecutor.rc and b/EgtExecutor.rc differ
diff --git a/LUA_GdbModifySurf.cpp b/LUA_GdbModifySurf.cpp
index 38ca77c..6324516 100644
--- a/LUA_GdbModifySurf.cpp
+++ b/LUA_GdbModifySurf.cpp
@@ -293,6 +293,29 @@ LuaCopySurfTmFacet( lua_State* L)
    return 1 ;
 }
 
+//----------------------------------------------------------------------------
+static int
+LuaCutSurfTm( 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) ;
+  // recupero i contorni della faccetta della superficie
+   bool bOk = ExeCutSurfTm( nId, ptOn, vtN, bSaveOnEq, nRefType) ;
+  // restituisco il risultato
+   LuaSetParam( L, bOk) ;
+   return 1 ;
+}
+
 //-------------------------------------------------------------------------------
 bool
 LuaInstallGdbModifySurf( LuaMgr& luaMgr)
@@ -311,5 +334,6 @@ LuaInstallGdbModifySurf( LuaMgr& luaMgr)
    bOk = bOk && luaMgr.RegisterFunction( "EgtGetSurfTmSilhouette", LuaGetSurfTmSilhouette) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtExtractSurfTmFacetLoops", LuaExtractSurfTmFacetLoops) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtCopySurfTmFacet", LuaCopySurfTmFacet) ;
+   bOk = bOk && luaMgr.RegisterFunction( "EgtCutSurfTm", LuaCutSurfTm) ;
    return bOk ;
 }