diff --git a/VolZmapVolume.cpp b/VolZmapVolume.cpp
index 291a068..48df158 100644
--- a/VolZmapVolume.cpp
+++ b/VolZmapVolume.cpp
@@ -1385,7 +1385,12 @@ SortGroupInters( PNTVEC3DVECTOR& vInters, INTINTVECTOR& vStartEnds, const Vector
 
 struct SurfBezForInters {
    SurfBezier sBez ;
-   BBox3d bbSurf ;
+   BBox3d bbSurfZ ;
+   BBox3d bbSurfX ;
+   BBox3d bbSurfY ;
+   Frame3d frZMainDim ;
+   Frame3d frXMainDim ;
+   Frame3d frYMainDim ;
    Vector3d a3, a2, a1, a0, b3, b2, b1, b0 ;
 };
 
@@ -1409,7 +1414,7 @@ IntersLineBezierSurfSet( const Point3d& ptLineStart, const Vector3d& vtLineDir,
       frRot.Set( ORIG, X_AX) ;
    if( bNeedToRotY)
       frRot.Set( ORIG, Y_AX) ;
-   if ( bNeedToRot ) {
+   if ( bNeedToRot) {
       r.ToLoc( frRot) ;
       q.ToLoc( frRot) ;
    }
@@ -1426,9 +1431,35 @@ IntersLineBezierSurfSet( const Point3d& ptLineStart, const Vector3d& vtLineDir,
          continue ;
 
       const SurfBezForInters& srf = vSurfBez[s] ;
-      BBox3d bbox = srf.bbSurf ;
-      if( bNeedToRot)
-         bbox.ToLoc( frRot) ;
+      BBox3d bbox ;
+      bool bNotValid = false ;
+      Point3d rLoc = r ;
+      if( ! bNeedToRot) {
+         bbox = srf.bbSurfZ ;
+         if( srf.frZMainDim.IsValid())
+            rLoc.ToLoc( srf.frZMainDim) ;
+      }
+      else if( bNeedToRotX) {
+         if( srf.frXMainDim.IsValid()) {
+            bbox = srf.bbSurfX ;
+            rLoc.LocToLoc(frRot, srf.frXMainDim) ;
+         }
+         else
+            bNotValid = true ;
+      }
+      else if( bNeedToRotY) {
+         if( srf.frYMainDim.IsValid()) {
+            bbox = srf.bbSurfY ;
+            rLoc.LocToLoc(frRot, srf.frYMainDim) ;
+         }
+         else
+            bNotValid = true ;
+      }
+
+      if( bNotValid) {
+         bbox = srf.bbSurfZ ;
+         bbox.ToLoc(frRot) ;
+      }
       INTDBLVECTOR vIntBoxBox ;
       bool bCalcInters = false ;
       int nInterv = -1 ;
@@ -1441,10 +1472,10 @@ IntersLineBezierSurfSet( const Point3d& ptLineStart, const Vector3d& vtLineDir,
             if( bCalcInters)
                nInterv = k ;
          }
-         bCalcInters = bCalcInters && bbox.SqDistFromPointXY( r) < EPS_ZERO ;
+         bCalcInters = bCalcInters && bbox.SqDistFromPointXY( rLoc) < EPS_ZERO ;
       }
       else
-         bCalcInters = bbox.SqDistFromPointXY( r) < EPS_ZERO ;
+         bCalcInters = bbox.SqDistFromPointXY( rLoc) < EPS_ZERO ;
 
       // verifico che lo spillone faccia interferenza con il box della superficie
       if ( bCalcInters) {
@@ -2123,10 +2154,10 @@ VolZmap::Comp_5AxisMilling( int nGrid, const PNTVECTOR& ptS, const PNTVECTOR& pt
                cArcTopStartBack2.SetC2PN( ptS.front(), vPntTopStartExB[2], vPntTopStartExB[1], vtLs.front()) ;
                PtrOwner<CurveBezier> cBezTopStartBack1( GetBasicCurveBezier(ArcToBezierCurve( &cArcTopStartBack1, nDegU, bRat))) ;
                PtrOwner<CurveBezier> cBezTopStartBack2( GetBasicCurveBezier(ArcToBezierCurve( &cArcTopStartBack2, nDegU, bRat))) ;
-               vvPtCtrl.emplace_back( PNTVECTOR{ ptS[s], ptS[s], ptS[s], ptS[s]}) ;
+               vvPtCtrl.emplace_back( PNTVECTOR{ ptS[0], ptS[0], ptS[0], ptS[0]}) ;
                PNTVECTOR vPntTopStartBack1 = cBezTopStartBack1->GetAllControlPoints() ;
                vvPtCtrl.back().insert( vvPtCtrl.back().end(), vPntTopStartBack1.begin(), vPntTopStartBack1.end()) ;
-               vvPtCtrl.emplace_back( PNTVECTOR{ ptS[s], ptS[s], ptS[s], ptS[s]}) ;
+               vvPtCtrl.emplace_back( PNTVECTOR{ ptS[0], ptS[0], ptS[0], ptS[0]}) ;
                PNTVECTOR vPntTopStartBack2 = cBezTopStartBack2->GetAllControlPoints() ;
                vvPtCtrl.back().insert( vvPtCtrl.back().end(), vPntTopStartBack2.begin(), vPntTopStartBack2.end()) ;
                if( n5AxisType != VolZmap::Move5Axis::ALONG_CONCAVE) {
@@ -2187,7 +2218,6 @@ VolZmap::Comp_5AxisMilling( int nGrid, const PNTVECTOR& ptS, const PNTVECTOR& pt
          vSurfBez[nSurfInd].sBez.SetControlPoint( 5, vvPtCtrl[z][5]) ;
          vSurfBez[nSurfInd].sBez.SetControlPoint( 6, vvPtCtrl[z][6]) ;
          vSurfBez[nSurfInd].sBez.SetControlPoint( 7, vvPtCtrl[z][7]) ;
-         vSurfBez[nSurfInd].bbSurf.Add( vvPtCtrl[z]) ;
 
          Vector3d A = vvPtCtrl[z][4] - vvPtCtrl[z][0] ;
          Vector3d B = vvPtCtrl[z][5] - vvPtCtrl[z][1] ;
@@ -2208,6 +2238,41 @@ VolZmap::Comp_5AxisMilling( int nGrid, const PNTVECTOR& ptS, const PNTVECTOR& pt
          vSurfBez[nSurfInd].b1 = -3*E + 3*F ;
          vSurfBez[nSurfInd].b0 = E ;
 
+         Vector3d vtDirX ;
+         Vector3d vtDir0 = vvPtCtrl[z][4] - vvPtCtrl[z][0] ;
+         Vector3d vtDir1 = vvPtCtrl[z][3] - vvPtCtrl[z][0] ;
+         if( vtDir0.Len() > vtDir1.Len())
+            vtDirX = vtDir0 ;
+         else
+            vtDirX = vtDir1 ;
+
+         // calcolo il box in un riferimento che usi come asse x la direzione P01 - P00 ( proiettata sul piano perperndicolare a Z)
+         if( vSurfBez[nSurfInd].frZMainDim.Set( ORIG, Z_AX, vtDirX)) {
+            // porto tutti i punti in quel riferimento e calcolo il box
+            PNTVECTOR vPtCtrlLoc = vvPtCtrl[z] ;
+            for( int p = 0 ; p < int( vPtCtrlLoc.size()) ; ++p)
+               vPtCtrlLoc[p].ToLoc( vSurfBez[nSurfInd].frZMainDim) ;
+            vSurfBez[nSurfInd].bbSurfZ.Add( vPtCtrlLoc) ;
+         }
+         else {
+            // in ogni caso definisco la box rispetto al rifemento di nGrid
+            vSurfBez[nSurfInd].bbSurfZ.Add( vvPtCtrl[z]) ;
+         }
+         if( vSurfBez[nSurfInd].frXMainDim.Set( ORIG, X_AX, vtDirX)) {
+            PNTVECTOR vPtCtrlLoc = vvPtCtrl[z] ;
+            // porto tutti i punti in quel riferimento e calcolo il box
+            for( int p = 0 ; p < int( vPtCtrlLoc.size()) ; ++p)
+               vPtCtrlLoc[p].ToLoc( vSurfBez[nSurfInd].frXMainDim) ;
+            vSurfBez[nSurfInd].bbSurfX.Add( vPtCtrlLoc) ;
+         }
+         if( vSurfBez[nSurfInd].frYMainDim.Set( ORIG, Y_AX, vtDirX)) {
+            PNTVECTOR vPtCtrlLoc = vvPtCtrl[z] ;
+            // porto tutti i punti in quel riferimento e calcolo il box
+            for( int p = 0 ; p < int( vPtCtrlLoc.size()) ; ++p)
+               vPtCtrlLoc[p].ToLoc( vSurfBez[nSurfInd].frYMainDim) ;
+            vSurfBez[nSurfInd].bbSurfY.Add( vPtCtrlLoc) ;
+         }
+         
 #ifdef TEST
             if ( nGrid == 0)
                vGeo.push_back( vSurfBez[nSurfInd].sBez.Clone()) ;
@@ -2218,7 +2283,7 @@ VolZmap::Comp_5AxisMilling( int nGrid, const PNTVECTOR& ptS, const PNTVECTOR& pt
 
 #ifdef TEST
    //debug
-   if ( nGrid == 0) {
+   if ( nGrid == 0  &&  false) {
       vector<Color> vCol( vGeo.size()) ;
       fill(vCol.begin(), vCol.end(), Color( 255,128,0)) ;
       SaveGeoObj( vGeo, vCol, "D:/Temp/VirtualMilling/5axisAdvanced/finalApprox.nge", 2) ;
@@ -2294,8 +2359,14 @@ VolZmap::Comp_5AxisMilling( int nGrid, const PNTVECTOR& ptS, const PNTVECTOR& pt
                if ( ! bForward  &&  vStartEnds.size() > 1) {
                   // salvo la prima intersezione dubbia e comincio a scorrere al contrario per trovare l'ultima e capire se è dello stesso tipo della prima
 
-                  if( ! bAllSameType  ||  false) {  // DEBUG  se a true !!!!!!!!!!!
+                  if( ! bAllSameType) {
                      bUseOnlyExtremes = false ;
+
+                     //debug
+                     string sOut = " calcoli addizionali per capire dentro/fouri" ; // debug
+                     LOG_INFO( GetEGkLogger(), sOut.c_str())
+                     //debug
+
                      // calcolo le intersezioni anche sugli altri due spilloni passanti per un punto a metà tra due dei vari intervalli
                      // ho almeno due intervalli; prendo un punto a metà tra la fine del primo e l'inzio del secondo
                      Point3d ptLineStart = (vInters[vStartEnds[0].second].first + vInters[vStartEnds[1].first].first ) / 2 ;
@@ -2340,12 +2411,6 @@ VolZmap::Comp_5AxisMilling( int nGrid, const PNTVECTOR& ptS, const PNTVECTOR& pt
                      // questo tipo e calcolare solo le intersezioni
                      if ( bUseOnlyExtremes == bFirstAmbiguousCaseType)
                         bAllSameType = true ;
-
-                     if ( bUseOnlyExtremes != bFirstAmbiguousCaseType && bAllSameType ) {
-                        string sOut = " Taglio multiplo ambiguo che avrebbe bisogno di più calcoli!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!" ; // debug
-                        LOG_INFO( GetEGkLogger(), sOut.c_str())
-                        return false ;
-                     }
                   }
 
                   if( ! bAllSameType)
@@ -2545,7 +2610,7 @@ bool
 VolZmap::MillingGeneralMotionStep( const Point3d& ptPs, const Vector3d& vtDs, const Vector3d& vtAs,
                                    const Point3d& ptPe, const Vector3d& vtDe, const Vector3d& vtAe)
 {
-#if true
+#if false
    #define OLD_LINEAR
 #endif