diff --git a/VolZmap.h b/VolZmap.h
index ec61132..01fcd39 100644
--- a/VolZmap.h
+++ b/VolZmap.h
@@ -304,6 +304,7 @@ class VolZmap : public IVolZmap, public IGeoObjRW
                                 int& nStI, int& nStJ, int& nEnI, int& nEnJ) ;
 
     // Asportazioni superfici elementari vuote
+      bool SurfCircCrown_ZDrilling( int nGrid, const Point3d& ptS, const Point3d& ptE, const Vector3d& vtAx, double dMaxRad, double dMinRad) ;
       /*bool SurfCyl_ZDrilling( int nGrid, const Point3d& ptS, const Point3d& ptE, const Vector3d& vtToolDir,
                               double dHei, double dRad, bool bTapB, bool bTapT) ;
       bool SurfCyl_Drilling( int nGrid, const Point3d& ptS, const Point3d& ptE, const Vector3d& vtToolDir,
@@ -314,9 +315,13 @@ class VolZmap : public IVolZmap, public IGeoObjRW
                             const Vector3d& vtToolDir, double dHei, double dRad, bool bOuterCutter, bool bTapB, bool bTapT) ;
       bool SurfConus_ZDrilling( int nGrid, const Point3d& ptS, const Point3d& ptE, const Vector3d& vtToolDir, double dHei, double dMaxRad, double dMinRad,
                                 bool bOuterCutter, const Vector3d& vtArcNormMaxR, const Vector3d& vtArcNormMinR) ;
+      bool SurfConus_Drilling( int nGrid, const Point3d& ptS, const Point3d& ptE, const Vector3d& vtToolDir, 
+                               double dHei, double dMaxRad, double dMinRad, bool bOuterCutter, bool bTapB, bool bTapT,
+                               const Vector3d& vtArcNormMaxR, const Vector3d& vtArcNormMinR) ;
       bool SurfConus_ZMilling( int nGrid, const Point3d& ptS, const Point3d& ptE, const Vector3d& vtToolDir, double dHei, double dMaxRad, double dMinRad,
                                bool bOuterCutter, const Vector3d& vtArcNormMaxR, const Vector3d& vtArcNormMinR) ;
 
+
     // Intersezioni
       bool IntersLineBox( const Point3d& ptP, const Vector3d& vtV, const Point3d& ptMin, const Point3d& ptMax) const ;
       bool IntersLineBox( const Point3d& ptP, const Vector3d& vtV, const Point3d& ptMin, const Point3d& ptMax,
diff --git a/VolZmapVolume.cpp b/VolZmapVolume.cpp
index c8a86d5..6dd268f 100644
--- a/VolZmapVolume.cpp
+++ b/VolZmapVolume.cpp
@@ -5050,6 +5050,50 @@ VolZmap::IntersLineSphereCuttedByPlanes( const Point3d& ptLineP, const Vector3d&
    return nSol ; 
 }
 
+// Corona circolare
+//----------------------------------------------------------------------------
+bool
+VolZmap::SurfCircCrown_ZDrilling( int nGrid, const Point3d& ptS, const Point3d& ptE, const Vector3d& vtAx, double dMaxRad, double dMinRad)
+{
+   // Verifica sull'interferenza utensile Zmap
+   int nStartI, nStartJ, nEndI, nEndJ ;
+   if ( ! TestCompoBBox( nGrid, ptS, ptE, vtToolDir, dMaxRad, dMinRad, 1, nStartI, nStartJ, nEndI, nEndJ))
+      return true ;
+
+   // Se il movimento č in direzione opposta a quella ove la corona puņ tagliare, non devo fare nulla. 
+   if ( vtAx.z * ( ptE - ptS).z < EPS_ZERO)
+      return true ;
+
+   // Raggi di sicurezza per evitare di tagliare i dexel a filo del bordo dela regione interessata dal taglio.
+   double dSqSafeMinRad = dMinRad * dMinRad + 2 * dMinRad * EPS_SMALL ;
+   double dSqSafeMaxRad = dMaxRad * dMaxRad - 2 * dMaxRad * EPS_SMALL ;
+
+   Point3d ptSXY( ptS.x, ptS.y, 0) ;
+
+   // Ciclo sui dexel.
+   for ( int i = nStartI ; i <= nEndI ; ++ i) {
+      for ( int j = nStartJ ; j <= nEndJ ; ++ j) {
+         Point3d ptC( ( i + 0.5) * m_dStep, ( j + 0.5) * m_dStep, 0) ;
+         Vector3d vtR = ptC - ptSXY ;
+         double dSqLenR = vtR * vtR ;
+         if ( dSqLenR > dSqSafeMinRad  &&  dSqLenR < dSqSafeMaxRad) {
+            double dMinZ = min( ptS.z, ptE.z) ;
+            double dMaxZ = max( ptS.z, ptE.z) ;
+            Vector3d vtMinN, vtMaxN ;
+            if ( ptE.z < ptS.z) {
+               vtMinN.z = 1 ;
+               vtMaxN;
+            }
+            else {
+               vtMinN;
+               vtMaxN.z = - 1 ;
+            }
+         }
+      }
+   }
+
+   return true ;
+}
 
 // Cilindro
 //----------------------------------------------------------------------------
@@ -5345,8 +5389,8 @@ VolZmap::SurfConus_ZDrilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
                double dDeltaH = dMinRad * dHei / ( dMaxRad - dMinRad) ;
                Point3d ptVertE = ptE - ( dHei + dDeltaH) * vtToolDir ;
                Point3d ptIntMinP( dX, dY, dMinZ) ;
-               Vector3d vtIntMinV = ptIntMin - ptVertE ;
-               double dCompLong = vtIntMin * vtToolDir ;
+               Vector3d vtIntMinV = ptIntMinP - ptVertE ;
+               double dCompLong = vtIntMinV * vtToolDir ;
                Vector3d vtIntMinLongV = dCompLong * vtToolDir ;
                Vector3d vtIntMinOrtV = vtIntMinV - vtIntMinLongV ;
                vtMinN = - vtIntMinOrtV + dCompLong * vtToolDir ;
@@ -5355,8 +5399,8 @@ VolZmap::SurfConus_ZDrilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
                double dDeltaH = dMinRad * dHei / ( dMaxRad - dMinRad) ;
                Point3d ptVertE = ptE - ( dHei + dDeltaH) * vtToolDir ;
                Point3d ptIntMaxP( dX, dY, dMaxZ) ;
-               Vector3d vtIntMaxV = ptIntMax - ptVertE ;
-               double dCompLong = vtIntMax * vtToolDir ;
+               Vector3d vtIntMaxV = ptIntMaxP - ptVertE ;
+               double dCompLong = vtIntMaxV * vtToolDir ;
                Vector3d vtIntMaxLongV = dCompLong * vtToolDir ;
                Vector3d vtIntMaxOrtV = vtIntMaxV - vtIntMaxLongV ;
                vtMaxN = vtIntMaxOrtV - dCompLong * vtToolDir ;
@@ -5373,8 +5417,8 @@ VolZmap::SurfConus_ZDrilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
                double dDeltaH = dMinRad * dHei / ( dMaxRad - dMinRad) ;
                Point3d ptVertE = ptE - ( dHei + dDeltaH) * vtToolDir ;
                Point3d ptIntMaxP( dX, dY, dMaxZ) ;
-               Vector3d vtIntMaxV = ptIntMax - ptVertE ;
-               double dCompLong = vtIntMax * vtToolDir ;
+               Vector3d vtIntMaxV = ptIntMaxP - ptVertE ;
+               double dCompLong = vtIntMaxV * vtToolDir ;
                Vector3d vtIntMaxLongV = dCompLong * vtToolDir ;
                Vector3d vtIntMaxOrtV = vtIntMaxV - vtIntMaxLongV ;
                vtMaxN = - vtIntMaxOrtV + dCompLong * vtToolDir ;
@@ -5383,8 +5427,8 @@ VolZmap::SurfConus_ZDrilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
                double dDeltaH = dMinRad * dHei / ( dMaxRad - dMinRad) ;
                Point3d ptVertE = ptE - ( dHei + dDeltaH) * vtToolDir ;
                Point3d ptIntMinP( dX, dY, dMinZ) ;
-               Vector3d vtIntMinV = ptIntMin - ptVertE ;
-               double dCompLong = vtIntMin * vtToolDir ;
+               Vector3d vtIntMinV = ptIntMinP - ptVertE ;
+               double dCompLong = vtIntMinV * vtToolDir ;
                Vector3d vtIntMinLongV = dCompLong * vtToolDir ;
                Vector3d vtIntMinOrtV = vtIntMinV - vtIntMinLongV ;
                vtMinN = vtIntMinOrtV - dCompLong * vtToolDir ;
@@ -5409,8 +5453,9 @@ VolZmap::SurfConus_Drilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
    // Vettore spostamento
    Vector3d vtDisp = ptE - ptS ;
 
-   if ( ( vtToolDir * vtDisp > 0  &&    bOuterCutter)  ||
-        ( vtToolDir * vtDisp < 0  &&  ! bOuterCutter))
+   bool bToolVecAndDispAreOpposite = vtToolDir * vtDisp < 0 ;
+   if ( ( ! bToolVecAndDispAreOpposite  &&    bOuterCutter)  ||
+        (   bToolVecAndDispAreOpposite  &&  ! bOuterCutter))
       return true ;
 
    // Vertici cono iniziale e finale
@@ -5436,7 +5481,7 @@ VolZmap::SurfConus_Drilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
          Vector3d vtN1, vtN2 ;
    
          // Intersezione con il cono in posizione iniziale
-         int nIntNum = IntersLineConeCuttedByPlanes( ptC, Z_AX, ptS, vtToolDir, dMaxRad, dHei, true,
+         int nIntNum = IntersLineConeCuttedByPlanes( ptC, Z_AX, ptS - dHei * vtToolDir, vtToolDir, dMaxRad, dHei, true,
                                                      vCutConePlaneVecSt, ptInt1, vtN1, ptInt2, vtN2);
          if ( nIntNum >= 1) {
             vParAndNormIntersVec.emplace_back() ;
@@ -5450,7 +5495,7 @@ VolZmap::SurfConus_Drilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
          }
    
          // Intersezione con il cono in posizione finale
-         nIntNum = IntersLineConeCuttedByPlanes( ptC, Z_AX, ptE, vtToolDir, dMaxRad, dHei, true,
+         nIntNum = IntersLineConeCuttedByPlanes( ptC, Z_AX, ptE - dHei * vtToolDir, vtToolDir, dMaxRad, dHei, true,
                                                  vCutConePlaneVecEn, ptInt1, vtN1, ptInt2, vtN2) ;
          if ( nIntNum >= 1) {
             vParAndNormIntersVec.emplace_back() ;
@@ -5464,7 +5509,7 @@ VolZmap::SurfConus_Drilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
          }
    
          // Intersezione con il cilindro esterno
-         nIntNum = IntersLineCylinderCuttedByPlanes( ptC, Z_AX, ptS, vtDisp * vtAx, dMaxRad, dHei, true,
+         nIntNum = IntersLineCylinderCuttedByPlanes( ptC, Z_AX, ptS, vtToolDir, dMaxRad, ( bToolVecAndDispAreOpposite ? - 1 : 1) * dHei, true,
                                                      vEmptyPlaneVec, ptInt1, vtN1, ptInt2, vtN2) ;
          if ( nIntNum >= 1) {
             vParAndNormIntersVec.emplace_back() ;
@@ -5478,7 +5523,7 @@ VolZmap::SurfConus_Drilling( int nGrid, const Point3d& ptS, const Point3d& ptE,
          }
    
          // Intersezione con il cilindro interno
-         nIntNum = IntersLineCylinderCuttedByPlanes( ptC, Z_AX, ptS - dHei * vtToolDir, vtToolDir, dMinRad, dHei, true,
+         nIntNum = IntersLineCylinderCuttedByPlanes( ptC, Z_AX, ptS/* - dHei * vtToolDir*/, vtToolDir, dMinRad, ( bToolVecAndDispAreOpposite ? - 1 : 1) * dHei, true,
                                                      vEmptyPlaneVec, ptInt1, vtN1, ptInt2, vtN2) ;
          if ( nIntNum >= 1) {
             vParAndNormIntersVec.emplace_back() ;