diff --git a/SurfBezier.cpp b/SurfBezier.cpp
index 70ebca4..70a730c 100644
--- a/SurfBezier.cpp
+++ b/SurfBezier.cpp
@@ -6520,12 +6520,12 @@ SurfBezier::CreateByIsoParamSet( const ICurve* pCurve0, const ICurve* pCurve1, c
          bool bSplitToAdd = true ;
          int c0 = 0, c1 = 0 ;
          while ( bSplitToAdd) {
-            if ( c0 > ssize( vdParamPos0) - 1 && c1 > ssize( vdParamPos1) - 1) {
+            if ( c0 > ssize( vdParamPos0) - 1 || c1 > ssize( vdParamPos1) - 1) {
                LOG_DBG_ERR( GetEGkLogger(), "Surf Bez Ruled Guided: error while reparametrizing some section") ;
                return false ;
             }
             // se ho una corrispondenza tra punti ( e non sono alla fine del tratto) allora non aggiungo split
-            if ( abs( vdParamPos0[c0] - vdParamPos1[c1]) < EPS_SMALL  &&  vdParamPos0[c0] < 1) {
+            if ( abs( vdParamPos0[c0] - vdParamPos1[c1]) < EPS_PARAM  &&  vdParamPos0[c0] < 1) {
                ++c0 ;
                ++c1 ;
                ++nLastParam0 ;
@@ -6535,14 +6535,17 @@ SurfBezier::CreateByIsoParamSet( const ICurve* pCurve0, const ICurve* pCurve1, c
             // se non ho corrispondenza allora aggiungo uno split sulla curva a cui manca il punto corrispondente
             else if ( vdParamPos0[c0] < vdParamPos1[c1]) {
                double dPar ; CrvU1.GetParamAtLength( dLenPrev1 + dLen1 * vdParamPos0[c0], dPar) ;
-               if ( abs( dPar - round( dPar)) > EPS_SMALL) {
-                  vdSplit1.push_back( dPar) ;
-                  nSplit1 = vdSplit1.size() ;
-               }
-               else if ( dPar = round( dPar) ;  dPar > nLastParam1){
-                  ++ c1 ;
-                  ++ nLastParam1 ;
+               if ( dPar > dLastParam1 + EPS_PARAM) {
+                  if ( abs( dPar - round( dPar)) > EPS_PARAM) {
+                     vdSplit1.push_back( dPar) ;
+                     nSplit1 = vdSplit1.size() ;
+                  }
+                  else if ( dPar = round( dPar) ;  dPar > nLastParam1){
+                     ++ c1 ;
+                     ++ nLastParam1 ;
+                  }
                }
+               dLastParam1 = dPar ;
                ++nLastParam0 ;
                vPairs.emplace_back( nLastParam0 + nSplit0, nLastParam1 + nSplit1) ;
                ++c0 ;
@@ -6550,14 +6553,17 @@ SurfBezier::CreateByIsoParamSet( const ICurve* pCurve0, const ICurve* pCurve1, c
             else if ( vdParamPos0[c0] > vdParamPos1[c1]) {
                double dPar ; CrvU0.GetParamAtLength( dLenPrev0 + dLen0 * vdParamPos1[c1], dPar) ;
                // se lo split non è in prossimità di una joint già esistente allora lo aggiungo
-               if ( abs( dPar - round( dPar)) > EPS_SMALL) {
-                  vdSplit0.push_back( dPar) ;
-                  nSplit0 = vdSplit0.size() ;
-               }
-               else if ( dPar = round( dPar) ;  dPar > nLastParam0){
-                  ++ c0 ;
-                  ++ nLastParam0 ;
+               if ( dPar > dLastParam0 + EPS_PARAM) {
+                  if ( abs( dPar - round( dPar)) > EPS_PARAM) {
+                     vdSplit0.push_back( dPar) ;
+                     nSplit0 = vdSplit0.size() ;
+                  }
+                  else if ( dPar = round( dPar) ;  dPar > nLastParam0){
+                     ++ c0 ;
+                     ++ nLastParam0 ;
+                  }
                }
+               dLastParam0 = dPar ;
                ++nLastParam1 ;
                vPairs.emplace_back( nLastParam0 + nSplit0, nLastParam1 + nSplit1) ;
                ++c1 ;