diff --git a/Milling.cpp b/Milling.cpp
index b7005fa..2f2921e 100644
--- a/Milling.cpp
+++ b/Milling.cpp
@@ -4371,6 +4371,9 @@ Milling::CalcTabsPositions( const ICurveComposite* pCompo, double dDepth, bool b
          while ( nTabId != GDB_ID_NULL) {
             Point3d ptCen ;
             if ( ExeCenterPoint( nTabId, GDB_ID_ROOT, ptCen)  &&  b3Mill.EnclosesXY( ptCen)) {
+              // porto il centro alla quota del percorso
+               ptCen += vtExtr * ( dDepth - m_Params.m_dTabHeight) ;
+              // calcolo la distanza del centro dal percorso
                double dDist ; double dPar, dAdjLen ; int nFlag ;
                DistPointCurve distPC( ptCen, *pCompo) ;
                if ( distPC.GetDist( dDist)  &&  dDist < dMaxDist  &&
@@ -4440,7 +4443,9 @@ Milling::CalcTabsPositions( const ICurveComposite* pCompo, double dDepth, bool b
       Point3d ptCen ;
       if ( pCompo->GetParamAtLength( dPos + dTabLen / 2, dU)  &&
            pCompo->GetPointD1D2( dU, ICurve::FROM_MINUS, ptCen)) {
+        // porto il centro alla quota del tab
          ptCen -= vtExtr * ( dDepth - m_Params.m_dTabHeight) ;
+        // creo il cerchio
          PtrOwner<ICurveArc> pCircle( CreateCurveArc()) ;
          if ( ! IsNull( pCircle)  &&  pCircle->Set( ptCen, vtExtr, m_TParams.m_dDiam / 2)) {
             int nCircId = m_pGeomDB->AddGeoObj( GDB_ID_NULL, nTabsId, Release( pCircle)) ;