diff --git a/CurveComposite.cpp b/CurveComposite.cpp
index f293018..1c7c520 100644
--- a/CurveComposite.cpp
+++ b/CurveComposite.cpp
@@ -1056,9 +1056,13 @@ CurveComposite::GetIndSCurveAndLocPar( double dU, Side nS, int& nSCrv, double& d
   // determino la curva di appartenenza e il valore locale (ovvero nella curva) del parametro
    nSCrv = static_cast<int>( dU) ;
    dLocU = dU - nSCrv ;
-   if ( fabs( dLocU) < EPS_PARAM  &&  nSCrv > 0  &&  nS == ICurve::FROM_MINUS) {
+   if ( fabs( dLocU) < 5 * EPS_PARAM  &&  nSCrv > 0  &&  nS == ICurve::FROM_MINUS) {
       -- nSCrv ;
-      dLocU += 1 ;
+      dLocU = 1 ;
+   }
+   else if ( fabs( dLocU) > 1 - 5 * EPS_PARAM  &&  nSCrv < dMaxU  &&  nS == ICurve::FROM_PLUS) {
+      ++ nSCrv ;
+      dLocU = 0 ;
    }
      
    return true ;
diff --git a/Simple CDSurfFrMove.cpp b/Simple CDSurfFrMove.cpp
index e951b96..07b55b5 100644
--- a/Simple CDSurfFrMove.cpp	
+++ b/Simple CDSurfFrMove.cpp	
@@ -140,7 +140,7 @@ MySimpleCDSurfFrMove::Translate( const Vector3d& vtDir, double& dLen)
                if ( pLine1 == nullptr  ||  pLine2 == nullptr  ||
                     ! TranslateLineNoCollisionLine( pLine1, pLine2, vtDirL, dNewLenXY, scInfoCurr))
                   return false ;
-               if ( abs( dNewLenXY - dPrevLenXY) < EPS_SMALL  &&  dNewLenXY < dLenXY - EPS_SMALL  ) {
+               if ( abs( dNewLenXY - dPrevLenXY) < EPS_SMALL) {
                   if ( scInfoCurr.nType == SCI_LINE_LINE  ||  scInfoCurr.nType == SCI_PNT_LINE) {
                      m_SCollInfo = scInfoCurr ;
                      m_SCollInfo.nChunkM = j ;
@@ -363,10 +363,12 @@ MySimpleCDSurfFrMove::TranslateLineNoCollisionLine( const CurveLine* pLine1, con
       }
    }
   // confronto con movimento corrente
-   if ( abs( dNewLen) < EPS_SMALL)
+   if ( dNewLen > - 5 * EPS_SMALL  &&  dNewLen < EPS_SMALL)
       dLen = 0 ;
-   else if ( dNewLen > 0)
-      dLen = min( dLen, dNewLen) ;
+   else if ( dNewLen > 0  &&  dNewLen < dLen)
+      dLen = dNewLen ;
+   else     // non c'è collisione, reset Info
+      scInfo.nType = SCI_NONE ;
    return true ;
 }
 
@@ -460,12 +462,16 @@ MySimpleCDSurfFrMove::RotateLineNoCollisionLine( const CurveLine* pLine1, const
 
   // verifico se gli intervalli radiali si sovrappongono
    Vector3d vtDirS1 = ptS1 - ptCen ;
+   vtDirS1.z = 0 ;
    double dRadS1 = vtDirS1.LenXY() ;
    Vector3d vtDirE1 = ptE1 - ptCen ;
+   vtDirE1.z = 0 ;
    double dRadE1 = vtDirE1.LenXY() ;
    Vector3d vtDirS2 = ptS2 - ptCen ;
+   vtDirS2.z = 0 ;
    double dRadS2 = vtDirS2.LenXY() ;
    Vector3d vtDirE2 = ptE2 - ptCen ;
+   vtDirE2.z = 0 ;
    double dRadE2 = vtDirE2.LenXY() ;
 
   // ordino l'intervallo della prima linea secondo raggi crescenti