diff --git a/MachMgr.h b/MachMgr.h
index 4f14980..70e492b 100644
--- a/MachMgr.h
+++ b/MachMgr.h
@@ -421,6 +421,7 @@ class MachMgr : public IMachMgr
       bool IsKinematicRotAxisBlocked( int nInd) const ;
       int  GetCalcTool( void) const ;
       double GetCalcRot1W( void) const ;
+      bool GetCalcPartDirFromAngles( const Vector3d& vtPart, const DBLVECTOR& vAng, Vector3d& vtDir) const ;
       bool SetCalcSolCh( int nScc, bool bExact) ;
       bool VerifyAngleOutstroke( int nInd, double dAng) const ;
       bool VerifyOutstroke( double dX, double dY, double dZ, const DBLVECTOR& vAng, bool bClear, int& nStat) const ;
diff --git a/MachMgrMachines.cpp b/MachMgrMachines.cpp
index 9ef0f5b..e2a3e37 100644
--- a/MachMgrMachines.cpp
+++ b/MachMgrMachines.cpp
@@ -651,6 +651,16 @@ MachMgr::GetCalcAuxDirFromAngles( const DBLVECTOR& vAng, Vector3d& vtDir) const
    return pMch->GetAuxDirFromAngles( vAng, vtDir) ;
 }
 
+//----------------------------------------------------------------------------
+bool
+MachMgr::GetCalcPartDirFromAngles( const Vector3d& vtPart, const DBLVECTOR& vAng, Vector3d& vtDir) const
+{
+   Machine* pMch = GetCurrMachine() ;
+   if ( pMch == nullptr)
+      return false ;
+   return pMch->GetPartDirFromAngles( vtPart, vAng, vtDir) ;
+}
+
 //----------------------------------------------------------------------------
 bool
 MachMgr::GetNearestAngleInStroke( int nInd, double dAngRef, double& dAng) const
diff --git a/Machine.h b/Machine.h
index 38528c4..93183e7 100644
--- a/Machine.h
+++ b/Machine.h
@@ -131,6 +131,7 @@ class Machine
                                 bool bBottom, bool bOverall, Point3d& ptTip) const ;
       bool GetToolDirFromAngles( const DBLVECTOR& vAng, Vector3d& vtDir) const ;
       bool GetAuxDirFromAngles( const DBLVECTOR& vAng, Vector3d& vtDir) const ;
+      bool GetPartDirFromAngles( const Vector3d& vtPart, const DBLVECTOR& vAng, Vector3d& vtDir) const ;
       bool GetBackToolDirFromAngles( const DBLVECTOR& vAng, Vector3d& vtDir) const ;
       bool GetBackAuxDirFromAngles( const DBLVECTOR& vAng, Vector3d& vtDir) const ;
       bool GetNearestAngleInStroke( int nInd, double dAngRef, double& dAng) const ;
diff --git a/MachineCalc.cpp b/MachineCalc.cpp
index e9de76c..a997a43 100644
--- a/MachineCalc.cpp
+++ b/MachineCalc.cpp
@@ -1191,6 +1191,29 @@ Machine::GetAuxDirFromAngles( const DBLVECTOR& vAng, Vector3d& vtDir) const
    return GetDirection( m_vtCalcADir, vAng, vtDir) ;
 }
 
+//----------------------------------------------------------------------------
+bool
+Machine::GetPartDirFromAngles( const Vector3d& vtPart, const DBLVECTOR& vAng, Vector3d& vtDir) const
+{
+  // è espressa nel riferimento di macchina (tiene conto delle sole rotazioni di tavola)
+
+  // verifico dimensione vettore angoli rispetto al numero di assi rotanti
+   if ( vAng.size() < m_vCalcRotAx.size())
+      return false ;
+
+  // direzione a riposo
+   vtDir = vtPart ;
+
+  // ciclo sugli assi dal primo (solo assi di tavola)
+   for ( size_t i = 1 ; i <= m_vCalcRotAx.size() ; ++ i) {
+     // se asse di tavola
+      if ( ! m_vCalcRotAx[i-1].bHead)
+         vtDir.Rotate( m_vCalcRotAx[i-1].vtDir, vAng[i-1]) ;
+   }
+
+   return true ;
+}
+
 //----------------------------------------------------------------------------
 bool
 Machine::GetBackToolDirFromAngles( const DBLVECTOR& vAng, Vector3d& vtDir) const
diff --git a/Operation.cpp b/Operation.cpp
index 7d386a9..caca693 100644
--- a/Operation.cpp
+++ b/Operation.cpp
@@ -1510,7 +1510,9 @@ Operation::CalculateClPathAxesValues( int nClPathId, int nLinAxes, int nRotAxes,
             if ( pCurve->GetType() == CRV_ARC) {
                ICurveArc* pArc = GetCurveArc( pCurve) ;
               // verifico il piano
-               if ( pArc->GetNormVersor() * pCamData->GetNormDir() < 0)
+               Vector3d vtRef ;
+               m_pMchMgr->GetCalcPartDirFromAngles( pCamData->GetNormDir(), vAngEnd, vtRef) ;
+               if ( pArc->GetNormVersor() * vtRef < 0)
                   pArc->InvertN() ;
               // assegno il centro e il raggio di questo arco ai dati cam
                pCamData->SetAxesCen( pArc->GetCenter()) ;