diff --git a/MachMgr.h b/MachMgr.h
index 56bc689..242ca96 100644
--- a/MachMgr.h
+++ b/MachMgr.h
@@ -298,7 +298,8 @@ class MachMgr : public IMachMgr
       bool MachiningUpdate( bool bPostApply = true) override ;
       bool PreparePreviewMachiningTool( void) const override ;
       bool RemovePreviewMachiningTool( void) const override ;
-      int  PreviewMachiningTool( int nEntId, int nFlag) const override ;
+      int  GetPreviewMachiningToolStepCount( void) const override ; 
+      int  PreviewMachiningTool( int nEntId, int nStep) const override ;
       bool GetMachiningParam( int nType, bool& bVal) const override ;
       bool GetMachiningParam( int nType, int& nVal) const override ;
       bool GetMachiningParam( int nType, double& dVal) const override ;
diff --git a/MachMgrOperations.cpp b/MachMgrOperations.cpp
index 2407be2..8622d99 100644
--- a/MachMgrOperations.cpp
+++ b/MachMgrOperations.cpp
@@ -1122,7 +1122,14 @@ MachMgr::RemovePreviewMachiningTool( void) const
 
 //----------------------------------------------------------------------------
 int
-MachMgr::PreviewMachiningTool( int nEntId, int nFlag) const
+MachMgr::GetPreviewMachiningToolStepCount( void) const
+{
+   return -1 ;
+}
+
+//----------------------------------------------------------------------------
+int
+MachMgr::PreviewMachiningTool( int nEntId, int nStep) const
 {
   // recupero la lavorazione corrente
    int nCurrMchId = GetCurrMachining() ;
@@ -1133,7 +1140,7 @@ MachMgr::PreviewMachiningTool( int nEntId, int nFlag) const
    if ( pMch == nullptr)
       return GDB_ID_NULL ;
   // eseguo
-   return pMch->ToolPreview( nEntId, nFlag) ;
+   return pMch->ToolPreview( nEntId, nStep) ;
 }
 
 //----------------------------------------------------------------------------
diff --git a/Machining.cpp b/Machining.cpp
index 66afae6..c7ecaad 100644
--- a/Machining.cpp
+++ b/Machining.cpp
@@ -176,6 +176,13 @@ Machining::RemoveToolPreview( void) const
 
 //----------------------------------------------------------------------------
 int
+Machining::GetToolPreviewStepCount( void) const
+{
+   return -1 ;
+}
+
+//----------------------------------------------------------------------------
+static int
 GetToolPreviewNext( IGeomDB* pGeomDB, int nEntId, int nParentId)
 {
   // recupero la successiva
@@ -201,7 +208,7 @@ GetToolPreviewNext( IGeomDB* pGeomDB, int nEntId, int nParentId)
 }
 
 //----------------------------------------------------------------------------
-int
+static int
 GetToolPreviewPrev( IGeomDB* pGeomDB, int nEntId, int nParentId)
 {
   // recupero la precedente
@@ -228,7 +235,7 @@ GetToolPreviewPrev( IGeomDB* pGeomDB, int nEntId, int nParentId)
 
 //----------------------------------------------------------------------------
 int
-Machining::ToolPreview( int nEntId, int nFlag) const
+Machining::ToolPreview( int nEntId, int nStep) const
 {
   // verifico validità gestori DB geometrico e CAM
    if ( m_pGeomDB == nullptr  ||  m_pMchMgr == nullptr)
@@ -248,10 +255,10 @@ Machining::ToolPreview( int nEntId, int nFlag) const
      // recupero il gruppo di appartenenza
       nParentId = m_pGeomDB->GetFirstGroupInGroup( nClId) ;
      // se richiesta successiva
-      if ( nFlag == MCH_TPM_AFTER)
+      if ( nStep > 0)
          nEntId = GetToolPreviewNext( m_pGeomDB, nEntId, nParentId) ;
      // se richiesta precedente
-      else if ( nFlag == MCH_TPM_BEFORE)
+      else if ( nStep < 0)
          nEntId = GetToolPreviewPrev( m_pGeomDB, nEntId, nParentId) ;
      // altrimenti richiesta corrente
       else
@@ -263,10 +270,10 @@ Machining::ToolPreview( int nEntId, int nFlag) const
       nParentId =  m_pGeomDB->GetParentId( nEntId) ;
       if ( m_pGeomDB->GetParentId( nParentId) == nClId) {
         // se richiesta successiva
-         if ( nFlag == MCH_TPM_AFTER)
+         if ( nStep > 0)
             nEntId = GetToolPreviewNext( m_pGeomDB, nEntId, nParentId) ;
         // se richiesta precedente
-         else if ( nFlag == MCH_TPM_BEFORE)
+         else if ( nStep < 0)
             nEntId = GetToolPreviewPrev( m_pGeomDB, nEntId, nParentId) ;
       }
       else
diff --git a/Machining.h b/Machining.h
index 1401b03..3979cc5 100644
--- a/Machining.h
+++ b/Machining.h
@@ -48,8 +48,9 @@ class Machining : public Operation
       bool GetStartPoint( Point3d& ptStart) const ;
       bool GetEndPoint( Point3d& ptEnd) const ;
       bool PrepareToolPreview( void) const ;
-      int  ToolPreview( int nEntId, int nFlag) const ;
       bool RemoveToolPreview( void) const ;
+      int  GetToolPreviewStepCount( void) const ;
+      int  ToolPreview( int nEntId, int nStep) const ;
 
    protected :
       Machining( void) ;
diff --git a/SawFinishing.cpp b/SawFinishing.cpp
index 849b4ea..a249837 100644
--- a/SawFinishing.cpp
+++ b/SawFinishing.cpp
@@ -1880,7 +1880,6 @@ SawFinishing::ClassifySection( ICurve* pCrv, INTVECTOR& vnClass)
 {
    const ICurveComposite* pCompo = GetCurveComposite( pCrv) ;
    if ( pCompo != nullptr) {
-      int Ind = 0 ;
       const ICurve* pSimpCrv = pCompo->GetFirstCurve() ;
       while ( pSimpCrv != nullptr) {
         // analizzo la curva
@@ -1898,7 +1897,6 @@ SawFinishing::ClassifySection( ICurve* pCrv, INTVECTOR& vnClass)
          else
             vnClass.push_back( CCL_FALL) ;
         // passo alla curva successiva
-         ++ Ind ;
          pSimpCrv = pCompo->GetNextCurve() ;
       }
    }