diff --git a/SawFinishing.cpp b/SawFinishing.cpp
index c475616..d1fa84d 100644
--- a/SawFinishing.cpp
+++ b/SawFinishing.cpp
@@ -3455,6 +3455,7 @@ SawFinishing::CalcAlong5ACuts( const SECTIONVECTOR& vSections, const Frame3d& fr
          continue ;
 
      // scorro le SubSection ottenute
+      bool bLastToolInv = false ;
       for ( int nSubSect = 0 ; nSubSect < ssize( Section.vSubSections) ; ++ nSubSect) {
 
         // recupero la SubSection corrente, se non valida, passo alla successiva
@@ -3480,6 +3481,7 @@ SawFinishing::CalcAlong5ACuts( const SECTIONVECTOR& vSections, const Frame3d& fr
         // Ciclo sulle passate
          double dLastElev ;
          Point3d ptStartPrev ;
+         Vector3d vtCorrPrev = V_NULL ;
          for ( int i = 0 ; i <= nStep ; ++ i) {
            // coordinate nel punto, del versore correzione e del versore utensile
             double dLcurr = i * dStep ;
@@ -3490,11 +3492,31 @@ SawFinishing::CalcAlong5ACuts( const SECTIONVECTOR& vSections, const Frame3d& fr
                return false ;
             Vector3d vtCorr = GetToGlob( vtTan, frSect) ;
             vtCorr.Rotate( vtGdDir, m_Params.m_bInvert ? - ANG_RIGHT : ANG_RIGHT) ;
+           // se tangente circa verticale
+            if ( abs( vtTan.y) < 2. * EPS_SMALL) {
+               if ( ( SubSection.nHeadSide == SAWFIN_HS_LEFT  &&  vtTan.y < 0.)  ||
+                    ( SubSection.nHeadSide == SAWFIN_HS_RIGHT  &&  vtTan.y > 0.))
+                  vtTan.y = - vtTan.y ;
+            }
             Vector3d vtTool = GetToGlob( vtTan, frSect) ;
 
-            // determino l'orientamento della testa
-            if ( vtTool.z < - EPS_ZERO)
+           // determino l'orientamento della testa
+            bool bCurrToolInv = false ;
+            if ( vtTool.z < - EPS_ZERO) {
                vtTool.Invert() ; // NB. vtTool deve sempre avere la componente Z come positiva
+               bCurrToolInv = true ;
+            }
+
+           // verifico se inversione della testa
+            bool bFirst = ( i == 0) ;
+            bool bSpecialAppr = ( m_Params.m_nLeadLinkType != SAWFIN_LL_CENT && ! bFirst && ( bCurrToolInv != bLastToolInv)) ;
+            if ( bSpecialAppr) {
+               SetFeed( GetEndFeed()) ;
+               Point3d ptCurr ; GetCurrPos( ptCurr) ;
+               if ( ! AddRetract( ptCurr, vtCorrPrev, GetSafeZ(), dLastElev, m_Params.m_dStartPos))
+                  return false ;
+            }
+            bLastToolInv = bCurrToolInv ;
 
            // se direzione utensile maggiore dell'angolo limite, blocco la direzione all'angolo limite
             if ( vtCorr * Z_AX < dCosAngLimit) {
@@ -3585,7 +3607,6 @@ SawFinishing::CalcAlong5ACuts( const SECTIONVECTOR& vSections, const Frame3d& fr
             SetToolDir( vtTool) ;
             SetCorrAuxDir( vtCorr) ;
            // se diverso da precedente, eseguo il taglio
-            bool bFirst = ( i == 0) ;
             dElev = dElev / max( EPS_SMALL, ( vtCorr * Z_AX)) ; // non serve fare il max, ma meglio prevenire...
             if ( bFirst  ||  ! AreSamePointEpsilon( ptStart, ptStartPrev, 10. * EPS_SMALL)) {
                if ( m_Params.m_nStepType != SAWFIN_ST_ZIGZAG) {
@@ -3593,13 +3614,14 @@ SawFinishing::CalcAlong5ACuts( const SECTIONVECTOR& vSections, const Frame3d& fr
                      return false ;
                }
                else {
-                  if ( ! CalcAlongZigZagCut( ptStart, ptEnd, vtGdDir, vtTool, vtCorr, dElev, bExtend, false, bFirst))
+                  if ( ! CalcAlongZigZagCut( ptStart, ptEnd, vtGdDir, vtTool, vtCorr, dElev, bExtend, false, bFirst, bSpecialAppr))
                      return false ;
                }
               // salvo dati correnti
                dLastElev = dElev ;
                ptStartPrev = ptStart ;
             }
+            vtCorrPrev = vtCorr ;
          }
         // se ZigZag e non centrato aggiungo risalita
          if ( m_Params.m_nStepType == SAWFIN_ST_ZIGZAG  &&  m_Params.m_nLeadLinkType != SAWFIN_LL_CENT) {
@@ -3670,8 +3692,8 @@ SawFinishing::CalcAlongOneWayCut( const Point3d& ptStart, const Point3d& ptEnd,
 
 //----------------------------------------------------------------------------
 bool
-SawFinishing::CalcAlongZigZagCut( const Point3d& ptStart, const Point3d& ptEnd, const Vector3d& vtDir,
-                                  const Vector3d& vtTool, const Vector3d& vtCorr, double dElev, bool bExtend, bool bVert, bool bFirst)
+SawFinishing::CalcAlongZigZagCut( const Point3d& ptStart, const Point3d& ptEnd, const Vector3d& vtDir, const Vector3d& vtTool,
+                                  const Vector3d& vtCorr, double dElev, bool bExtend, bool bVert, bool bFirst, bool bAppr)
 {
   // recupero distanza di sicurezza
    double dSafeZ = GetSafeZ() ;
@@ -3712,14 +3734,14 @@ SawFinishing::CalcAlongZigZagCut( const Point3d& ptStart, const Point3d& ptEnd,
 
   // Sempre una sola passata
   // 1 -> approccio
-   if ( bFirst  ||  m_Params.m_nLeadLinkType == SAWFIN_LL_CENT) {
+   if ( bFirst  ||  m_Params.m_nLeadLinkType == SAWFIN_LL_CENT  ||  bAppr) {
       if ( ! AddApproach( ptNewStart, vtCorr, dSafeZ, dElev, dAppr))
          return false ;
    }
   // 2 -> movimento in affondo al punto iniziale
    SetFlag( 0) ;
    // con attacco centrato sono sul materiale e devo usare feed di testa
-   if ( m_Params.m_nLeadLinkType == SAWFIN_LL_CENT) {
+   if ( m_Params.m_nLeadLinkType == SAWFIN_LL_CENT  ||  bAppr) {
       SetFeed( GetTipFeed()) ;
       if ( AddLinearMove( ptNewStart) == GDB_ID_NULL)
          return false ;
diff --git a/SawFinishing.h b/SawFinishing.h
index b23ec98..1f26338 100644
--- a/SawFinishing.h
+++ b/SawFinishing.h
@@ -127,8 +127,8 @@ class SawFinishing : public Machining
                             const BBox3d& b3Raw, const ISurfTriMesh* pStmRaw) ;
       bool CalcAlongOneWayCut( const Point3d& ptStart, const Point3d& ptEnd, const Vector3d& vtDir,
                                const Vector3d& vtTool, const Vector3d& vtCorr, double dElev, bool bExtend, bool bVert) ;
-      bool CalcAlongZigZagCut( const Point3d& ptStart, const Point3d& ptEnd, const Vector3d& vtDir,
-                               const Vector3d& vtTool, const Vector3d& vtCorr, double dElev, bool bExtend, bool bVert, bool bFirst) ;
+      bool CalcAlongZigZagCut( const Point3d& ptStart, const Point3d& ptEnd, const Vector3d& vtDir, const Vector3d& vtTool,
+                               const Vector3d& vtCorr, double dElev, bool bExtend, bool bVert, bool bFirst, bool bAppr = false) ;
       bool CalcAcrossOneWayCut( const PolyLine& PL, const Vector3d& vtMove,
                                 const Vector3d& vtTool, const Vector3d& vtCorr, double dRawZ, double dDepth) ;
       bool CalcAcrossZigZagCut( const PolyLine& PL, const Vector3d& vtMove,