diff --git a/Simulator.cpp b/Simulator.cpp
index a3a74f4..765cf0b 100644
--- a/Simulator.cpp
+++ b/Simulator.cpp
@@ -65,6 +65,7 @@ Simulator::Simulator( void)
    m_nAuxETot = 0 ;
    m_nAuxEInd = 0 ;
    m_nExit = 0 ;
+   m_dTDiam = 0 ;
    m_dVmTdOffs = 0 ;
    m_dVmAdOffs = 0 ;
    m_dSafeDist = SAFEDIST_STD ;
@@ -124,6 +125,9 @@ Simulator::Start( bool bFirst)
 
   // Reset utensile, interpolazione e assi correnti
    m_sTool.clear() ;
+   m_sHead.clear() ;
+   m_nExit = 0 ;
+   m_dTDiam = 0 ;
    ResetInterpolation() ;
    ResetAxes() ;
    ResetAuxAxes() ;
@@ -444,6 +448,7 @@ Simulator::UpdateTool( bool bFirst)
          m_sTool = sTool ;
          m_sHead = sHead ;
          m_nExit = nExit ;
+         m_pMchMgr->TdbGetCurrToolParam( TPA_DIAM, m_dTDiam) ;
         // aggiorno gli assi macchina
          if ( ! UpdateAxes())
             return false ;
@@ -488,6 +493,7 @@ Simulator::UpdateTool( bool bFirst)
       m_sTool = sTool ;
       m_sHead = sHead ;
       m_nExit = nExit ;
+      m_pMchMgr->TdbGetCurrToolParam( TPA_DIAM, m_dTDiam) ;
      // aggiorno gli assi macchina
       if ( ! UpdateAxes())
          return false ;
@@ -928,7 +934,8 @@ Simulator::ManageSingleMove( int& nStatus, double& dMove)
       double dPrevCoeff = m_dCoeff ;
       double dDist = sqrt( dSqDist) ;
       if ( dDist > EPS_SMALL) {
-         int nStep = int( max( dDist / ( ( nMoveType == 0 ? 2 : 1) * m_dStep), 1.)) ;
+         double dStep = min( ( nMoveType == 0 ? 2 : 1) * m_dStep, MAX_STEP) ;
+         int nStep = int( max( dDist / dStep, 1.)) ;
          m_dCoeff += 1. / nStep ;
          if ( m_dCoeff > 1)
             m_dCoeff = 1 ;
@@ -948,7 +955,7 @@ Simulator::ManageSingleMove( int& nStatus, double& dMove)
       if ( nMoveType != 2  &&  nMoveType != 3) {
         // se attivo CollisionCheck approssimo movimento con pių step
          int nStep = 1 ;
-         if ( ! m_VmId.empty()  ||  NeedCollisionCheck()) {
+         if ( NeedCollisionCheck()) {
             const double LEN_STEP = 10. ;
             nStep = max( int( dDist / LEN_STEP), 1) ;
          }
@@ -964,17 +971,17 @@ Simulator::ManageSingleMove( int& nStatus, double& dMove)
                double dVal = m_AuxAxesVal[j] * ( 1 - dCurrCoeff) + m_AuxAxesEnd[j] * dCurrCoeff ;
                m_pMachine->SetAxisPos( m_AuxAxesName[j], dVal) ;
             }
-           // eseguo eventuale Vmill
-            Point3d ptNoseF ; Vector3d vtDirF ; Vector3d vtAuxF ;
-            bool bOkF = GetHeadCurrPosDirAux( ptNoseF, vtDirF, vtAuxF) ;
-            for ( int j = 0 ; j < int( m_VmId.size()) ; ++ j) {
-               Frame3d frVzmF ;
-               bOkF = m_pGeomDB->GetGlobFrame( m_VmId[j], frVzmF) && bOkF ;
-               ExecLineVmill( m_VmId[j], ptNoseI, vtDirI, vtAuxI, vFrVzmI[j], ptNoseF, vtDirF, vtAuxF, frVzmF) ;
-            }
            // eseguo eventuale collision check
             bCollCheck = bCollCheck && ExecCollisionCheck( nCdInd, nObjInd) ;
          }
+        // eseguo eventuale Vmill
+         Point3d ptNoseF ; Vector3d vtDirF ; Vector3d vtAuxF ;
+         bool bOkF = GetHeadCurrPosDirAux( ptNoseF, vtDirF, vtAuxF) ;
+         for ( int j = 0 ; j < int( m_VmId.size()) ; ++ j) {
+            Frame3d frVzmF ;
+            bOkF = m_pGeomDB->GetGlobFrame( m_VmId[j], frVzmF) && bOkF ;
+            ExecLineVmill( m_VmId[j], ptNoseI, vtDirI, vtAuxI, vFrVzmI[j], ptNoseF, vtDirF, vtAuxF, frVzmF) ;
+         }
       }
      // Eseguo movimento su arco
       else {
@@ -990,8 +997,10 @@ Simulator::ManageSingleMove( int& nStatus, double& dMove)
         // se attivi Vmill o CollisionCheck approssimo movimento con pių step
          int nStep = 1 ;
          if ( ! m_VmId.empty()  ||  NeedCollisionCheck()) {
-            const double LEN_STEP = 2. ;
-            nStep = max( int( abs( dDiffAng * DEGTORAD * dRad) / LEN_STEP), 1) ;
+            const double MIN_LEN_STEP = 2. ;
+            const double MAX_LEN_STEP = 10. ;
+            double dLenStep = Clamp( 0.1 * m_dTDiam, MIN_LEN_STEP, MAX_LEN_STEP) ;
+            nStep = max( int( abs( dDiffAng * DEGTORAD * dRad) / dLenStep), 1) ;
             const double ANG_STEP = 5. ;
             if ( abs( dDiffAng) / nStep > ANG_STEP)
                nStep = int( abs( dDiffAng) / ANG_STEP) ;
@@ -1149,7 +1158,7 @@ Simulator::ExecLineVmill( int nVmId, const Point3d& ptHi, const Vector3d& vtHi,
 bool
 Simulator::ExecCollisionCheck( int& nCdInd, int& nObjInd)
 {
-  // se non ci sono oggetti da controllare o non ci sono i grezzi o equivalenti, tutto bene
+  // se non ci sono oggetti da controllare o non ci sono grezzi o equivalenti, tutto bene
    if ( ! NeedCollisionCheck())
       return true ;
   // ciclo sui grezzi o equivalenti
@@ -1169,7 +1178,6 @@ Simulator::ExecCollisionCheck( int& nCdInd, int& nObjInd)
       Frame3d frCd ; m_pGeomDB->GetGlobFrame( m_CdId[i], frCd) ;
      // ciclo sugli oggetti con cui verificare
       for ( int j = 0 ; j < int( m_CollObj.size()) ; ++ j) {
-         bool bOk = true ;
         // se modo hidden č da saltare
          int nMode ;
          if ( m_pGeomDB->GetCalcMode( m_CollObj[j].nFrameId, nMode)  &&  nMode == GDB_MD_HIDDEN)
@@ -1185,6 +1193,8 @@ Simulator::ExecCollisionCheck( int& nCdInd, int& nObjInd)
          const IGeoFrame3d* pGeoFrame = GetGeoFrame3d( m_pGeomDB->GetGeoObj( m_CollObj[j].nFrameId)) ;
          if ( pGeoFrame == nullptr)
             continue ;
+        // esecuzione controlli di collisione
+         bool bOk = true ;
          Frame3d frObj = pGeoFrame->GetFrame() ;
          Frame3d frParent ; m_pGeomDB->GetGlobFrame( m_CollObj[j].nFrameId, frParent) ;
          frObj.LocToLoc( frParent, frCd) ;
diff --git a/Simulator.h b/Simulator.h
index c98670c..23d2506 100644
--- a/Simulator.h
+++ b/Simulator.h
@@ -121,6 +121,7 @@ class Simulator
       std::string   m_sTool ;                // nome dell'utensile corrente
       std::string   m_sHead ;                // nome della testa corrente
       int           m_nExit ;                // indice dell'uscita corrente
+      double        m_dTDiam ;               // diametro dell'utensile corrente
       INTVECTOR     m_VmId ;                 // vettore identificativi Zmap per Virtual Milling
       INTVECTOR     m_CdId ;                 // vettore identificativi Zmap per Collision Detection
       double        m_dVmTdOffs ;            // offset utensile in direzione principale per VM