diff --git a/CDeCylClosedSurfTm.cpp b/CDeCylClosedSurfTm.cpp
index b9e6ca8..2f28a2e 100644
--- a/CDeCylClosedSurfTm.cpp
+++ b/CDeCylClosedSurfTm.cpp
@@ -27,10 +27,16 @@ CDeCylClosedSurfTm( const Frame3d& frCyl, double dH, double dR, double dSafeDist
       return false ;
   // recupero BBox del poliedro
    BBox3d b3Poly = Stm.GetAllTriaBox() ;
+  // sistemazioni cilindro
+   Frame3d frC = frCyl ;
+   if ( dH < 0) {
+      frC.Translate( dH * frC.VersZ()) ;
+      dH = - dH ;
+   }
   // calcolo il BBox del cilindro
-   BBox3d b3Cyl( ORIG, dR, dR, dH) ;
+   BBox3d b3Cyl( -dR, -dR, 0, dR, dR, dH) ;
    b3Cyl.Expand( dSafeDist) ;
-   b3Cyl.ToGlob( frCyl) ;
+   b3Cyl.ToGlob( frC) ;
   // confronto i due Box
    if ( ! b3Cyl.Overlaps( b3Poly))
       return false ;
@@ -40,7 +46,7 @@ CDeCylClosedSurfTm( const Frame3d& frCyl, double dH, double dR, double dSafeDist
    for ( int nT : vT) {
       Triangle3d Tria ;
       if ( Stm.GetTriangle( nT, Tria)) {
-         if ( CDeCylTria( frCyl, dH, dR, dSafeDist, Tria))
+         if ( CDeCylTria( frC, dH, dR, dSafeDist, Tria))
             return true ;
       }
    }
diff --git a/CDeCylTria.cpp b/CDeCylTria.cpp
index 1557e4f..1636cc2 100644
--- a/CDeCylTria.cpp
+++ b/CDeCylTria.cpp
@@ -44,7 +44,7 @@ CDeCylTria( const Frame3d& frCyl, double dH, double dR, double dSafeDist, const
   // Verifico che sia orientato verso l'alto
    if ( plyTria.GetVersN().z < - EPS_SMALL)
       plyTria.Invert() ;
-  // Determino la distanza con segno dei lati del poligono dall'origine del piano
+  // Determino la distanza con segno dei lati del poligono convesso dall'origine del piano
    const PNTVECTOR& vVert = plyTria.GetVertices() ;
    for ( int i = 0 ; i < int( vVert.size()) ; ++ i) {
       int j = ( i + 1) % vVert.size() ;
@@ -61,6 +61,6 @@ CDeCylTria( const Frame3d& frCyl, double dH, double dR, double dSafeDist, const
             return false ;
       }
    }
-
-   return false ;
+  // Non sta a destra di alcun lato, deve collidere
+   return true ;
 }
diff --git a/EgtGeomKernel.rc b/EgtGeomKernel.rc
index b9b5c63..aacde69 100644
Binary files a/EgtGeomKernel.rc and b/EgtGeomKernel.rc differ