diff --git a/Milling.cpp b/Milling.cpp
index 9bb4d56..98f53f7 100644
--- a/Milling.cpp
+++ b/Milling.cpp
@@ -181,6 +181,7 @@ Milling::Milling( void)
    m_TParams.m_sName = "*" ;
    m_TParams.m_sHead = "*" ;
    m_nMills = 0 ;
+   m_bStepOn = false ;
 }
 
 //----------------------------------------------------------------------------
@@ -1360,6 +1361,7 @@ Milling::ProcessPath( int nPathId, int nPvId, int nClId)
    }
 
   // eventuale sovrapposizione per percorso chiuso
+   double dAddedOverlap = 0 ;
    if ( pCompo->IsClosed()) {
       if ( m_Params.m_dOverlap > EPS_SMALL) {
          double dParS, dParE ;
@@ -1368,6 +1370,7 @@ Milling::ProcessPath( int nPathId, int nPvId, int nClId)
             PtrOwner<ICurve> pCrv( pCompo->CopyParamRange( dParS, dParE)) ;
             if ( ! IsNull( pCrv)) {
                pCompo->AddCurve( Release( pCrv)) ;
+               dAddedOverlap = m_Params.m_dOverlap ;
             }
          }
       }
@@ -1531,22 +1534,30 @@ Milling::ProcessPath( int nPathId, int nPvId, int nClId)
 
      // Se una sola passata
       if ( dOkStep < EPS_SMALL  ||  dElev <= dOkStep) {
-        // eseguo lavorazione
+         m_bStepOn = false ;
          if ( ! AddStandardMilling( pCompo, vtTool, vtExtr, dDepth, dElev, bSplitArcs))
             return false ;
       }
      // se altrimenti passate a zig-zag
       else if ( m_Params.m_nStepType == MILL_ST_ZIGZAG) {
+         m_bStepOn = true ;
          if ( ! AddZigZagMilling( pCompo, vtTool, vtExtr, dDepth, dElev, dOkStep, bSplitArcs))
             return false ;
       }
      // se altrimenti passate a one-way
       else if ( m_Params.m_nStepType == MILL_ST_ONEWAY) {
+         m_bStepOn = true ;
          if ( ! AddOneWayMilling( pCompo, vtTool, vtExtr, dDepth, dElev, dOkStep, bSplitArcs))
             return false ;
       }
      // se altrimenti passate a spirale
       else if ( m_Params.m_nStepType == MILL_ST_SPIRAL) {
+         m_bStepOn = true ;
+         if ( dAddedOverlap > EPS_SMALL) {
+            pCompo->Invert() ;
+            pCompo->TrimStartAtLen( dAddedOverlap) ;
+            pCompo->Invert() ;
+         }
          if ( ! AddSpiralMilling( pCompo, vtTool, vtExtr, dDepth, dElev, dOkStep, bSplitArcs))
             return false ;
       }
@@ -2641,10 +2652,10 @@ Milling::GetLeadInType( void) const
          ( m_Params.m_dLiTang < min( 0.1 * m_TParams.m_dDiam, 1.0)  ||  m_Params.m_dLiElev < 10 * EPS_SMALL))
       return MILL_LI_NONE ;
    if ( ( m_Params.m_nLeadInType == MILL_LI_HELIX  ||  m_Params.m_nLeadInType == MILL_LI_ZIGZAG)  &&
-        m_Params.m_nStepType == MILL_ST_ZIGZAG)
+        m_bStepOn  &&  m_Params.m_nStepType == MILL_ST_ZIGZAG)
       return MILL_LI_NONE ;
    if ( ( m_Params.m_nLeadInType == MILL_LI_HELIX  ||  m_Params.m_nLeadInType == MILL_LI_ZIGZAG)  &&
-        m_Params.m_nStepType == MILL_ST_SPIRAL)
+        m_bStepOn  &&  m_Params.m_nStepType == MILL_ST_SPIRAL)
       return MILL_LI_NONE ;
    if ( ( m_Params.m_nLeadInType == MILL_LI_HELIX  ||  m_Params.m_nLeadInType == MILL_LI_ZIGZAG)  &&
         ( m_TParams.m_nType & TF_SAWBLADE) != 0)
@@ -2887,7 +2898,8 @@ Milling::AddLeadOut( const Point3d& ptEnd, const Vector3d& vtEnd, const Vector3d
    double dElev = min( m_Params.m_dLoElev, dEndElev + LIO_ELEV_TOL) ;
   // se uscita come ingresso o step invertito
    if ( nType == MILL_LO_AS_LI  ||  bInvert) {
-      switch ( GetLeadInType()) {
+      int nLiType = GetLeadInType() ;
+      switch ( nLiType) {
       case MILL_LI_LINEAR : nType = MILL_LO_LINEAR ; break ;
       case MILL_LI_TANGENT : nType = MILL_LO_TANGENT ; break ;
       case MILL_LI_GLIDE : nType = MILL_LO_GLIDE ; break ;
@@ -2897,6 +2909,10 @@ Milling::AddLeadOut( const Point3d& ptEnd, const Vector3d& vtEnd, const Vector3d
       }
       dTang = m_Params.m_dLiTang ;
       dPerp = m_Params.m_dLiPerp ;
+      if ( nLiType == MILL_LI_HELIX) {
+         dTang = 0.5 * min( m_Params.m_dLiTang, m_TParams.m_dDiam) ;
+         dPerp = dTang ;
+      }
       dElev = min( m_Params.m_dLiElev, dEndElev + LIO_ELEV_TOL) ;
    }
   // senso di rotazione da dir tg a dir esterna
diff --git a/Milling.h b/Milling.h
index a3828ee..1a26e2d 100644
--- a/Milling.h
+++ b/Milling.h
@@ -121,6 +121,7 @@ class Milling : public Machining
       MillingData   m_Params ;          // parametri lavorazione
       ToolData      m_TParams ;         // parametri utensile
       int           m_nMills ;          // numero di percorsi di lavoro generati
+      bool          m_bStepOn ;         // flag per indicare che effettivamente si lavora a step
       bool          m_bAggrBottom ;     // flag utilizzo di aggregato da sotto
       Vector3d      m_vtAggrBottom ;    // vettore direzione ausiliaria aggregato da sotto
       AggrBottom    m_AggrBottom ;      // dati eventuale aggregato da sotto