diff --git a/Drilling.cpp b/Drilling.cpp
index 88c016f..5570995 100644
--- a/Drilling.cpp
+++ b/Drilling.cpp
@@ -823,6 +823,8 @@ Drilling::MultiHeadDrilling( int nExitCnt, const SELVECTOR& vId, int nClId, TABM
    Point3d ptExit ;
    m_pMchMgr->GetCurrMachine()->GetHeadExitPosDirAux( sHead, nMainToolInd + 1, ptExit, vtTool, vtAux) ;
    vTools[nMainToolInd].ptToolTip = ptExit - vtTool * vTools[nMainToolInd].pTool->m_dLen ;
+   if ( vtAux.IsSmall()  &&  m_pMchMgr->GetCurrMachine()->GetCurrRotAxes() == 0)
+      vtAux = FromUprightOrtho( vtTool) ;
    if ( vtTool.IsSmall()  ||  vtAux.IsSmall()) {
       m_pMchMgr->SetLastError( 2117, "Error in Drilling : incorrect multi drilling head") ;
       return false ;
@@ -1066,6 +1068,8 @@ Drilling::CalcMask( VECTORHOLE& vHoles, const VECTORTOOL& vTools, int nIndMT, co
      // nuova configurazione del versore A ottenuta
       if ( ! m_pMchMgr->GetCalcAuxDirFromAngles( vAng1, vtAnew))
          continue ;
+      if ( vtAnew.IsSmall()  &&  m_pMchMgr->GetCurrMachine()->GetCurrRotAxes() == 0)
+         vtAnew = vtAux ;
 
      // creo un nuovo sistema di riferimento centrato nel Tool principale
       Frame3d frMT ;