diff --git a/Machining.cpp b/Machining.cpp
index 0b64532..356e280 100644
--- a/Machining.cpp
+++ b/Machining.cpp
@@ -26,10 +26,9 @@
 
 using namespace std ;
 
-#define DEBUG 0
+#define DEBUG_PRV 1
 
-const string KEY_AXIS_GROUP = "PreviewAxisGroup" ;
-const string KEY_ROT_AXIS_VAL = "PreviewRotAxisVal" ;    // salvata per ogni gruppo di Preview
+const string KEY_PRV_ROTAXIS_VAL = "PreviewRotAxisVal" ;    // salvata per ogni gruppo di Preview
 
 // struttura per informazioni sugli assi
 struct PreviewAxisInfo {
@@ -395,7 +394,7 @@ Machining::MyPrepareToolPreview( bool bDouble)
                          m_pGeomDB->SetName( nNewTabRotAxisId, sName) ;
             double dAxisPos = 0. ;
             bOk = bOk && pMch->GetAxisPos( sName, dAxisPos) &&
-                         m_pGeomDB->SetInfo( nNewTabRotAxisId, KEY_ROT_AXIS_VAL, dAxisPos) ;
+                         m_pGeomDB->SetInfo( nNewTabRotAxisId, KEY_PRV_ROTAXIS_VAL, dAxisPos) ;
             if ( ! bOk)
                return false ;
             nCurrHierarchyId = nNewTabRotAxisId ;
@@ -505,7 +504,7 @@ Machining::MyPrepareToolPreview( bool bDouble)
               // memorizzo la sua posizione iniziale
                double dAxisPos = 0. ;
                bOk = bOk && pMch->GetAxisPos( sParentName, dAxisPos) &&
-                            m_pGeomDB->SetInfo( nNewParentId, KEY_ROT_AXIS_VAL, dAxisPos) ;
+                            m_pGeomDB->SetInfo( nNewParentId, KEY_PRV_ROTAXIS_VAL, dAxisPos) ;
             }
            // scorro i suoi figli
             int nChildId = m_pGeomDB->GetFirstInGroup( nParentId) ;
@@ -569,41 +568,33 @@ Machining::MyPrepareToolPreview( bool bDouble)
 
   // recupero il punto Tip dell'utensile e lo inserisco dentro al gruppo testa corrente
    int nExitGrpId = ( ! bDouble ? pMch->GetCurrExit() : pMch->GetExitId( sHead, nExitDBLId)) ;
-   bool bOk = ( nExitGrpId != GDB_ID_NULL) ;
+   if ( nExitGrpId == GDB_ID_NULL)
+      return false ;
    string sExitGrpName ; 
-   bOk = bOk && m_pGeomDB->GetName( nExitGrpId, sExitGrpName) ;
-   int nFrId = GDB_ID_NULL ;
-   if ( bOk) {
-      if ( ! bDouble) {
-         nFrId = m_pGeomDB->GetFirstNameInGroup( m_nPreviewHeadId, "_" + sExitGrpName) ;
-         m_nPreviewExitId = m_pGeomDB->GetFirstNameInGroup( m_nPreviewHeadId, sExitGrpName) ;
-      }
-      else {
-         nFrId = m_pGeomDB->GetFirstNameInGroup( m_nPreviewHeadIdDBL, "_" + sExitGrpName) ;
-         m_nPreviewExitIdDBL = m_pGeomDB->GetFirstNameInGroup( m_nPreviewHeadIdDBL, sExitGrpName) ;
-      }
+   if ( ! m_pGeomDB->GetName( nExitGrpId, sExitGrpName))
+      return false ;
+   if ( ! bDouble)
+      m_nPreviewExitId = m_pGeomDB->GetFirstNameInGroup( m_nPreviewHeadId, sExitGrpName) ;
+   else
+      m_nPreviewExitIdDBL = m_pGeomDB->GetFirstNameInGroup( m_nPreviewHeadIdDBL, sExitGrpName) ;
+  // determino le coordinate del Tip in locale
+   const Frame3d* pfrExit = m_pGeomDB->GetGroupFrame( nExitGrpId) ;
+   if ( pfrExit == nullptr)
+      return false ;
+   Point3d ptToolTip = pfrExit->Orig() - dTLen * pfrExit->VersZ() ;
+  // creo l'oggetto punto nel DBG
+   PtrOwner<IGeoPoint3d> ptGToolTip( CreateGeoPoint3d()) ;
+   if ( IsNull( ptGToolTip)  ||  ! ptGToolTip->Set( ptToolTip))
+      return false ;
+   if ( ! bDouble) {
+      m_nPreviewToolTip = m_pGeomDB->AddGeoObj( GDB_ID_NULL, m_nPreviewHeadId, Release( ptGToolTip)) ;
+      return ( m_nPreviewToolTip != GDB_ID_NULL) ;
    }
-   bOk = bOk && ( nFrId != GDB_ID_NULL) ;
-   const IGeoFrame3d* frExit = ( bOk ? GetGeoFrame3d( m_pGeomDB->GetGeoObj( nFrId)) : nullptr) ;
-   bOk = bOk && ( frExit != nullptr) ;
-   Point3d ptToolTip = ( bOk ? ( frExit->GetFrame()).Orig() - dTLen * ( frExit->GetFrame()).VersZ() : P_INVALID) ;
-   bOk = bOk && ptToolTip.IsValid() ;
-   if ( bOk) {
-      PtrOwner<IGeoPoint3d> ptGToolTip( CreateGeoPoint3d()) ;
-      bOk = ( ! IsNull( ptGToolTip) && ptGToolTip->Set( ptToolTip)) ;
-      if ( bOk) {
-         if ( ! bDouble) {
-            m_nPreviewToolTip = m_pGeomDB->AddGeoObj( GDB_ID_NULL, m_nPreviewHeadId, Release( ptGToolTip)) ;
-            bOk = bOk && ( m_nPreviewToolTip != GDB_ID_NULL) ;
-         }
-         else {
-            m_nPreviewToolTipDBL = m_pGeomDB->AddGeoObj( GDB_ID_NULL, m_nPreviewHeadIdDBL, Release( ptGToolTip)) ;
-            bOk = bOk && ( m_nPreviewToolTipDBL != GDB_ID_NULL) ;
-         }
-      }
+   else {
+      m_nPreviewToolTipDBL = m_pGeomDB->AddGeoObj( GDB_ID_NULL, m_nPreviewHeadIdDBL, Release( ptGToolTip)) ;
+      return ( m_nPreviewToolTipDBL != GDB_ID_NULL) ;
    }
-
-   return bOk ;
+   
 }
 
 //----------------------------------------------------------------------------
@@ -695,7 +686,7 @@ Machining::RemoveToolPreview( void)
   // verifico validità gestore DB geometrico
    if ( m_pGeomDB == nullptr)
       return false ;
-   #if DEBUG
+   #if DEBUG_PRV
       return true ;
    #endif
   // recupero i gruppi per l'anteprima utensile
@@ -901,7 +892,7 @@ Machining::MyToolPreview( int nEntId, bool bDouble) const
          return false ;
      // recupero il valore corrente dell'asse
       double dCurrAxisVal = 0. ;
-      m_pGeomDB->GetInfo( nAxisId, KEY_ROT_AXIS_VAL, dCurrAxisVal) ;
+      m_pGeomDB->GetInfo( nAxisId, KEY_PRV_ROTAXIS_VAL, dCurrAxisVal) ;
      // recupero il valore dell'asse
       bool bFound = false ;
       double dAxisVal = 0 ;
@@ -922,7 +913,7 @@ Machining::MyToolPreview( int nEntId, bool bDouble) const
       Vector3d vtDir = pGV->GetVector() ;
       vtDir.Normalize() ;
       m_pGeomDB->RotateGroup( nAxisId, ptPos, vtDir, ( dAxisVal - dCurrAxisVal)) ;
-      m_pGeomDB->SetInfo( nAxisId, KEY_ROT_AXIS_VAL, dAxisVal) ;
+      m_pGeomDB->SetInfo( nAxisId, KEY_PRV_ROTAXIS_VAL, dAxisVal) ;
    }
 
   // recupero la posizione del tip dell'utensile per movimento assi lineari