diff --git a/EXE_GeoInters.cpp b/EXE_GeoInters.cpp
index 25c6a6a..2ac6a3f 100644
--- a/EXE_GeoInters.cpp
+++ b/EXE_GeoInters.cpp
@@ -35,6 +35,7 @@
 #include "/EgtDev/Include/EGkIntersPlaneSurfTm.h"
 #include "/EgtDev/Include/EGkIntersSurfTmSurfTm.h"
 #include "/EgtDev/Include/EGkStringUtils3d.h"
+#include "/EgtDev/Include/EgtNumUtils.h"
 #include "/EgtDev/Include/EgtPointerOwner.h"
 
 using namespace std ;
@@ -370,7 +371,7 @@ ExeLineSurfTmInters( const Point3d& ptP, const Vector3d& vtDir, int nId, int nRe
 
 //-------------------------------------------------------------------------------
 static int
-MyPlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDestGrpId, int nRefType,
+MyPlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDestGrpId, int nRefType, double dToler,
                      int& nPntCount, int& nCrvCount, int& nSrfCount)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
@@ -425,7 +426,6 @@ MyPlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDes
       ++ nPntCount ;
    }
   // Inserisco le curve nel DB (dopo averle concatenate)
-   double dToler = 20 * EPS_SMALL ;
    ChainCurves chainC ;
    chainC.Init( false, dToler, int( vBpt.size())) ;
    for ( int i = 0 ; i < int( vBpt.size()) ; ++ i) {
@@ -443,22 +443,22 @@ MyPlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDes
       if ( IsNull( pCrvCompo))
          return GDB_ID_NULL ;
      // recupero gli estremi dei segmenti, creo le linee e le inserisco nella composita
+      bool bAdded = true ;
       for ( int i = 0 ; i < int( vId.size()) ; ++ i) {
-        // creo una segmento di retta
-         int nInd = abs( vId[i]) - 1 ;
-         bool bInvert = ( vId[i] < 0) ;
+        // creo un segmento di retta
          PtrOwner<ICurveLine> pLine( CreateCurveLine()) ;
-         if ( IsNull( pLine)  ||  ! pLine->Set( vBpt[nInd].first, vBpt[nInd].second))
+         if ( IsNull( pLine))
             return GDB_ID_NULL ;
-         if ( bInvert)
-            pLine->Invert() ;
-        // lo accodo alla composita
-         if ( ! pCrvCompo->AddCurve( Release( pLine), true, dToler))
-            return GDB_ID_NULL ;
-        // aggiorno il prossimo near
-         ptNear = vBpt[nInd].second ;
+        // recupero gli estremi (non vanno mai invertiti per opzione di concatenamento)
+         int nInd = abs( vId[i]) - 1 ;
+         Point3d ptStart = ( bAdded ? vBpt[nInd].first : ptNear) ;
+         Point3d ptEnd = vBpt[nInd].second ;
+        // provo ad accodarlo alla composita
+         bAdded = ( pLine->Set( ptStart, ptEnd)  &&
+                    pCrvCompo->AddCurve( Release( pLine), true, dToler)) ;
+         ptNear = ( bAdded ? ptEnd : ptStart) ;
       }
-     // se lunghezza curva inferiore a 5 volte la tolleranza, la salto
+     // se lunghezza curva inferiore a 5 volte la tolleranza, la ignoro
       double dCrvLen ;
       if ( ! pCrvCompo->GetLength( dCrvLen)  ||  dCrvLen < 5. * dToler)
          continue ;
@@ -522,12 +522,12 @@ MyPlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDes
 
 //-------------------------------------------------------------------------------
 int
-ExePlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDestGrpId, int nRefType,
+ExePlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDestGrpId, int nRefType, double dToler,
                       int* pnPntCount, int* pnCrvCount, int* pnSrfCount)
 {
   // eseguo
    int nPntCount{ 0}, nCrvCount{ 0}, nSrfCount{ 0} ;
-   int nFirstId = MyPlaneSurfTmInters( ptOn, vtN, nId, nDestGrpId, nRefType, nPntCount, nCrvCount, nSrfCount) ;
+   int nFirstId = MyPlaneSurfTmInters( ptOn, vtN, nId, nDestGrpId, nRefType, dToler, nPntCount, nCrvCount, nSrfCount) ;
   // aggiorno contatori
    if ( nFirstId != GDB_ID_NULL) {
       if ( pnPntCount != nullptr)
@@ -544,7 +544,8 @@ ExePlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDe
                                                ToString( vtN) + "}," +
                                                ToString( nId) + "," +
                                                ToString( nDestGrpId) + "," +
-                                               RefTypeToString( nRefType) + ")" +
+                                               RefTypeToString( nRefType) + "," +
+                                               ToString( dToler) + ")" +
                     " -- Id1=" + ToString( nFirstId) + ", PntNbr=" + ToString( nPntCount) +
                     ", CrvNbr=" + ToString( nCrvCount) + ", SrfNbr=" + ToString( nSrfCount) ;
       LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
@@ -555,10 +556,10 @@ ExePlaneSurfTmInters( const Point3d& ptOn, const Vector3d& vtN, int nId, int nDe
 
 //-------------------------------------------------------------------------------
 static bool
-MyChainCurvesForSurfSurfInters( const BIPNTVECTOR& vBpt, IGeomDB* pGeomDB, int nDestGrpId, int nId1, int& nFirstId, int& nCrvCount)
+MyChainCurvesForSurfSurfInters( const BIPNTVECTOR& vBpt, IGeomDB* pGeomDB, int nDestGrpId, int nId1, double dToler,
+                                int& nFirstId, int& nCrvCount)
 {
   // Concateno i tratti di curva
-   const double dToler = 20 * EPS_SMALL ;
    ChainCurves chainC ;
    chainC.Init( false, dToler, int( vBpt.size())) ;
    for ( int i = 0 ; i < int( vBpt.size()) ; ++ i) {
@@ -577,21 +578,20 @@ MyChainCurvesForSurfSurfInters( const BIPNTVECTOR& vBpt, IGeomDB* pGeomDB, int n
       if ( IsNull( pCrvCompo))
          return false ;
      // recupero gli estremi dei segmenti, creo le linee e le inserisco nella composita
+      bool bAdded = true ;
       for ( int i = 0 ; i < int( vId.size()) ; ++ i) {
         // creo un segmento di retta
-         int nInd = abs( vId[i]) - 1 ;
-         bool bInvert = ( vId[i] < 0) ;
          PtrOwner<ICurveLine> pLine( CreateCurveLine()) ;
-         if ( IsNull( pLine)  ||  ! pLine->Set( vBpt[nInd].first, vBpt[nInd].second))
-            return false ;
-         if ( bInvert)
-            pLine->Invert() ;
-        // lo accodo alla composita
-         if ( ! pCrvCompo->AddCurve( Release( pLine), true, 1.1 * dToler)  &&
-              ! AreSamePointApprox( ptNear, ( bInvert ? vBpt[nInd].first : vBpt[nInd].second)))
-            return false ;
-        // aggiorno il prossimo near
-         ptNear = ( bInvert ? vBpt[nInd].first : vBpt[nInd].second) ;
+         if ( IsNull( pLine))
+            return GDB_ID_NULL ;
+        // recupero gli estremi (non vanno mai invertiti per opzione di concatenamento)
+         int nInd = abs( vId[i]) - 1 ;
+         Point3d ptStart = ( bAdded ? vBpt[nInd].first : ptNear) ;
+         Point3d ptEnd = vBpt[nInd].second ;
+        // provo ad accodarlo alla composita
+         bAdded = ( pLine->Set( ptStart, ptEnd)  &&
+                    pCrvCompo->AddCurve( Release( pLine), true, dToler)) ;
+         ptNear = ( bAdded ? ptEnd : ptStart) ;
       }
      // se lunghezza curva inferiore a 5 volte la tolleranza, la salto
       double dCrvLen ;
@@ -663,7 +663,7 @@ MyChainCurvesForSurfSurfInters( const BIPNTVECTOR& vBpt, IGeomDB* pGeomDB, int n
 
 //-------------------------------------------------------------------------------
 static int
-MySurfTmSurfTmInters( int nId1, int nId2, int nDestGrpId,
+MySurfTmSurfTmInters( int nId1, int nId2, int nDestGrpId, double dToler,
                       int& nPntCount, int& nCrvCount, int& nSrfCount)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
@@ -711,7 +711,7 @@ MySurfTmSurfTmInters( int nId1, int nId2, int nDestGrpId,
       ++ nPntCount ;
    }
   // Inserisco le curve nel DB (dopo averle concatenate)
-   if ( ! MyChainCurvesForSurfSurfInters( vBpt, pGeomDB, nDestGrpId, nId1, nFirstId, nCrvCount))
+   if ( ! MyChainCurvesForSurfSurfInters( vBpt, pGeomDB, nDestGrpId, nId1, dToler, nFirstId, nCrvCount))
       return GDB_ID_NULL ;
   // Inserisco i triangoli nel DB (dopo averli uniti in una superficie trimesh)
    StmFromTriangleSoup StmFts ;
@@ -744,12 +744,12 @@ MySurfTmSurfTmInters( int nId1, int nId2, int nDestGrpId,
 
 //-------------------------------------------------------------------------------
 int
-ExeSurfTmSurfTmInters( int nId1, int nId2, int nDestGrpId,
+ExeSurfTmSurfTmInters( int nId1, int nId2, int nDestGrpId, double dToler,
                        int* pnPntCount, int* pnCrvCount, int* pnSrfCount)
 {
   // eseguo
    int nPntCount{ 0}, nCrvCount{ 0}, nSrfCount{ 0} ;
-   int nFirstId = MySurfTmSurfTmInters( nId1, nId2, nDestGrpId, nPntCount, nCrvCount, nSrfCount) ;
+   int nFirstId = MySurfTmSurfTmInters( nId1, nId2, nDestGrpId, dToler, nPntCount, nCrvCount, nSrfCount) ;
   // aggiorno contatori
    if ( nFirstId != GDB_ID_NULL) {
       if ( pnPntCount != nullptr)
@@ -764,7 +764,8 @@ ExeSurfTmSurfTmInters( int nId1, int nId2, int nDestGrpId,
    if ( IsCmdLog()) {
       string sLua = "EgtSurfTmSurfTmInters(" + ToString( nId1) + "," +
                                                ToString( nId2) + "," +
-                                               ToString( nDestGrpId) + ")" +
+                                               ToString( nDestGrpId) + "," +
+                                               ToString( dToler) + ")" +
                     " -- Id1=" + ToString( nFirstId) + ", PntNbr=" + ToString( nPntCount) +
                     ", CrvNbr=" + ToString( nCrvCount) + ", SrfNbr=" + ToString( nSrfCount) ;
       LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
diff --git a/EgtExecutor.rc b/EgtExecutor.rc
index d28f99b..3eb3697 100644
Binary files a/EgtExecutor.rc and b/EgtExecutor.rc differ
diff --git a/LUA_GeoInters.cpp b/LUA_GeoInters.cpp
index c812b93..a9d3a1d 100644
--- a/LUA_GeoInters.cpp
+++ b/LUA_GeoInters.cpp
@@ -124,7 +124,7 @@ LuaLineSurfTmInters( lua_State* L)
 static int
 LuaPlaneSurfTmInters( lua_State* L)
 {
-  // 4 o 5 parametri : ptOn, vtN, Id, nDestGrpId [, nRefType]
+  // 4 o 5 o 6 parametri : ptOn, vtN, Id, nDestGrpId [, nRefType] [, dToler]
    Point3d ptOn ;
    LuaCheckParam( L, 1, ptOn)
    Vector3d vtN ;
@@ -134,13 +134,15 @@ LuaPlaneSurfTmInters( lua_State* L)
    int nDestGrpId ;
    LuaGetParam( L, 4, nDestGrpId) ;
    int nRefType = RTY_DEFAULT ;
-   LuaGetParam( L, 5, nRefType) ;
+   double dToler = 20 * EPS_SMALL ;
+   if ( LuaGetParam( L, 5, nRefType))
+      LuaGetParam( L, 6, dToler) ;
    LuaClearStack( L) ;
   // eseguo l'intersezione
    int nPntCount = 0 ;
    int nCrvCount = 0 ;
    int nSrfCount = 0 ;
-   int nNewId = ExePlaneSurfTmInters( ptOn, vtN, nId, nDestGrpId, nRefType, &nPntCount, &nCrvCount, &nSrfCount) ;
+   int nNewId = ExePlaneSurfTmInters( ptOn, vtN, nId, nDestGrpId, nRefType, dToler, &nPntCount, &nCrvCount, &nSrfCount) ;
   // restituisco il risultato
    if ( nNewId != GDB_ID_NULL)
       LuaSetParam( L, nNewId) ;
@@ -156,19 +158,21 @@ LuaPlaneSurfTmInters( lua_State* L)
 static int
 LuaSurfTmSurfTmInters( lua_State* L)
 {
-  // 3 parametri : Id1, nId2, nDestGrpId
+  // 3 o 4 parametri : Id1, nId2, nDestGrpId [, dToler]
    int nId1 ;
    LuaCheckParam( L, 1, nId1)
    int nId2 ;
    LuaCheckParam( L, 2, nId2)
    int nDestGrpId ;
    LuaCheckParam( L, 3, nDestGrpId) ;
+   double dToler = 20 * EPS_SMALL ;
+   LuaGetParam( L, 4, dToler) ;
    LuaClearStack( L) ;
   // eseguo l'intersezione
    int nPntCount = 0 ;
    int nCrvCount = 0 ;
    int nSrfCount = 0 ;
-   int nNewId = ExeSurfTmSurfTmInters( nId1, nId2, nDestGrpId, &nPntCount, &nCrvCount, &nSrfCount) ;
+   int nNewId = ExeSurfTmSurfTmInters( nId1, nId2, nDestGrpId, dToler, &nPntCount, &nCrvCount, &nSrfCount) ;
   // restituisco il risultato
    if ( nNewId != GDB_ID_NULL)
       LuaSetParam( L, nNewId) ;