diff --git a/EgtGeomKernel.rc b/EgtGeomKernel.rc
index 5ee6bbf..ad05311 100644
Binary files a/EgtGeomKernel.rc and b/EgtGeomKernel.rc differ
diff --git a/OffsetCurveOnX.cpp b/OffsetCurveOnX.cpp
index 9ffc3ca..2e0cb5e 100644
--- a/OffsetCurveOnX.cpp
+++ b/OffsetCurveOnX.cpp
@@ -245,9 +245,9 @@ OffsetCurveOnX::Make( const ICurve* pCrv, double dDist)
    for ( auto iIter = m_CrvLst.begin() ; iIter != m_CrvLst.end() ;) {
       ICurve* pCrv = *iIter ;
      // distanza minima di alcuni punti interni della curva dalla curva originale
-      if ( ! SafeDist( dDist, 0.5, pCrv, &ccCopy)  ||
-           ! SafeDist( dDist, 0.25, pCrv, &ccCopy)  ||
-           ! SafeDist( dDist, 0.75, pCrv, &ccCopy)) {
+      if ( ! SafeDist( dDist, 0.53, pCrv, &ccCopy)  ||
+           ! SafeDist( dDist, 0.13, pCrv, &ccCopy)  ||
+           ! SafeDist( dDist, 0.89, pCrv, &ccCopy)) {
          delete pCrv ;
          iIter = m_CrvLst.erase( iIter) ;
          continue ;
@@ -452,15 +452,15 @@ SafeDist( double dDist, double dCoeff, ICurve* pCrv1, ICurve* pCrv2)
   // calcolo il punto e due vicini
    double dUStart, dUEnd ;
    pCrv1->GetDomain( dUStart, dUEnd) ;
-   double dU = dCoeff * dUStart + ( 1 - dCoeff) * dUEnd ;
+   double dU = ( 1 - dCoeff) * dUStart + dCoeff * dUEnd ;
    Point3d ptP ;
    pCrv1->GetPointD1D2( dU, ICurve::FROM_MINUS, ptP) ;
    Point3d ptPrev, ptNext ;
    Vector3d vtPrev, vtNext ;
-   pCrv1->GetPointTang( dU - 100 * EPS_PARAM, ICurve::FROM_MINUS, ptPrev, vtPrev) ;
-   pCrv1->GetPointTang( dU + 100 * EPS_PARAM, ICurve::FROM_PLUS, ptNext, vtNext) ;
-  // non si considerano i tratti orizzontali (tolleranza fino a 5deg)
-   const double SEN_ANG_LIM = 0.0872 ;
+   pCrv1->GetPointTang( dU - 100 * EPS_PARAM, ICurve::FROM_PLUS, ptPrev, vtPrev) ;
+   pCrv1->GetPointTang( dU + 100 * EPS_PARAM, ICurve::FROM_MINUS, ptNext, vtNext) ;
+  // non si considerano i tratti orizzontali (tolleranza fino a 1deg)
+   const double SEN_ANG_LIM = 0.0175 ;
    if ( abs( vtPrev.y) < SEN_ANG_LIM  ||  abs( vtNext.y) < SEN_ANG_LIM)
       return true ;
   // segmento orizzontale di prova centrato sul punto e lungo dDist + dDist