diff --git a/SurfFinishing.cpp b/SurfFinishing.cpp
index d34fb7b..3e2fe90 100644
--- a/SurfFinishing.cpp
+++ b/SurfFinishing.cpp
@@ -1391,9 +1391,9 @@ SurfFinishing::AddZigZag( ICAvToolSurfTm* pCAvTlStm, const Frame3d& frSurf,
                while ( currPU != vPntU.end()) {
                   auto nextPU = next( currPU) ;
                   bool bNext = ( nextPU != vPntU.end()) ;
-                  bool bNextDown = ( bNext ? nextPU->second > -10 * EPS_SMALL : true) ;
+                  bool bNextDown = ( bNext ? nextPU->second > -m_Params.m_dApprox : true) ;
                  // punto corrente è al minimo
-                  if ( currPU->second > -10 * EPS_SMALL) {
+                  if ( currPU->second > -m_Params.m_dApprox) {
                     // se precedente e successivo al minimo, cancello e basta
                      if ( bPrevDwn  &&  bNextDown) {
                         if ( ! ptPrev.IsValid()  ||  abs( currPU->first.y - ptPrev.y) > 10 * EPS_SMALL)