diff --git a/EXE_GdbModifyVol.cpp b/EXE_GdbModifyVol.cpp
index f80c209..fa47142 100644
--- a/EXE_GdbModifyVol.cpp
+++ b/EXE_GdbModifyVol.cpp
@@ -510,7 +510,7 @@ ExeVolZmapAvoidBox( int nId, const Frame3d& frBox, const Vector3d& vtDiag, doubl
   // porto in locale il riferimento (il vettore è già in locale a questo stesso riferimento)
    Frame3d frBoxL = GetFrameLocal( pGeomDB, frBox, nRefType, frLoc) ;
   // recupero lo Zmap e calcolo collisione
-   IVolZmap* pVZM = GetVolZmap( pGeomDB->GetGeoObj( nId)) ;
+   const IVolZmap* pVZM = GetVolZmap( pGeomDB->GetGeoObj( nId)) ;
    bOk = bOk && ( pVZM != nullptr  &&  pVZM->AvoidBox( frBoxL, vtDiag, dSafeDist)) ;
   // se richiesto, salvo il comando Lua equivalente
    if ( IsCmdLog()) {
@@ -529,34 +529,6 @@ ExeVolZmapAvoidBox( int nId, const Frame3d& frBox, const Vector3d& vtDiag, doubl
    return bOk ;
 }
 
-//----------------------------------------------------------------------------
-bool
-ExeVolZmapAvoidSphere( int nId, const Point3d& ptCen, double dRad, double dSafeDist, int nRefType)
-{
-   IGeomDB* pGeomDB = GetCurrGeomDB() ;
-   VERIFY_GEOMDB( pGeomDB, false)
-  // recupero il riferimento locale
-   Frame3d frLoc ;
-   bool bOk = pGeomDB->GetGlobFrame( nId, frLoc) ;
-  // porto in locale il centro della sfera
-   Point3d ptCenL = GetPointLocal( pGeomDB, ptCen, nRefType, frLoc) ;
-  // recupero lo Zmap e calcolo collisione
-   IVolZmap* pVZM = GetVolZmap( pGeomDB->GetGeoObj( nId)) ;
-   bOk = bOk && ( pVZM != nullptr  &&  pVZM->AvoidSphere( ptCenL, dRad, dSafeDist)) ;
-  // se richiesto, salvo il comando Lua equivalente
-   if ( IsCmdLog()) {
-      string sLua = "EgtVolZmapAvoidSphere(" + IdToString( nId) + ",{" +
-                                               ToString( ptCen) + "}," +
-                                               ToString( dRad) + "," +
-                                               ToString( dSafeDist) + "," +
-                                               RefTypeToString( nRefType) + ")" +
-                    " -- Ok=" + ToString( bOk) ;
-      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
-   }
-  // restituisco risultato
-   return bOk ;
-}
-
 //----------------------------------------------------------------------------
 bool
 ExeVolZmapAvoidCylinder( int nId, const Frame3d& frCyl, double dL, double dR, double dSafeDist, int nRefType)
@@ -569,7 +541,7 @@ ExeVolZmapAvoidCylinder( int nId, const Frame3d& frCyl, double dL, double dR, do
   // porto in locale il riferimento
    Frame3d frBoxL = GetFrameLocal( pGeomDB, frCyl, nRefType, frLoc) ;
   // recupero lo Zmap e calcolo collisione
-   IVolZmap* pVZM = GetVolZmap( pGeomDB->GetGeoObj( nId)) ;
+   const IVolZmap* pVZM = GetVolZmap( pGeomDB->GetGeoObj( nId)) ;
    bOk = bOk && ( pVZM != nullptr  &&  pVZM->AvoidCylinder( frBoxL, dL, dR, dSafeDist)) ;
   // se richiesto, salvo il comando Lua equivalente
    if ( IsCmdLog()) {
@@ -589,6 +561,34 @@ ExeVolZmapAvoidCylinder( int nId, const Frame3d& frCyl, double dL, double dR, do
    return bOk ;
 }
 
+//----------------------------------------------------------------------------
+bool
+ExeVolZmapAvoidSphere( int nId, const Point3d& ptCen, double dRad, double dSafeDist, int nRefType)
+{
+   IGeomDB* pGeomDB = GetCurrGeomDB() ;
+   VERIFY_GEOMDB( pGeomDB, false)
+  // recupero il riferimento locale
+   Frame3d frLoc ;
+   bool bOk = pGeomDB->GetGlobFrame( nId, frLoc) ;
+  // porto in locale il centro della sfera
+   Point3d ptCenL = GetPointLocal( pGeomDB, ptCen, nRefType, frLoc) ;
+  // recupero lo Zmap e calcolo collisione
+   const IVolZmap* pVZM = GetVolZmap( pGeomDB->GetGeoObj( nId)) ;
+   bOk = bOk && ( pVZM != nullptr  &&  pVZM->AvoidSphere( ptCenL, dRad, dSafeDist)) ;
+  // se richiesto, salvo il comando Lua equivalente
+   if ( IsCmdLog()) {
+      string sLua = "EgtVolZmapAvoidSphere(" + IdToString( nId) + ",{" +
+                                               ToString( ptCen) + "}," +
+                                               ToString( dRad) + "," +
+                                               ToString( dSafeDist) + "," +
+                                               RefTypeToString( nRefType) + ")" +
+                    " -- Ok=" + ToString( bOk) ;
+      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
+   }
+  // restituisco risultato
+   return bOk ;
+}
+
 //-------------------------------------------------------------------------------
 bool
 ExeCutVolZmapPlane( int nId, const Point3d& ptOn, const Vector3d& vtN, int nRefType)
diff --git a/LUA_GdbModifyVol.cpp b/LUA_GdbModifyVol.cpp
index 69315f7..f516bb3 100644
--- a/LUA_GdbModifyVol.cpp
+++ b/LUA_GdbModifyVol.cpp
@@ -379,29 +379,6 @@ LuaVolZmapAvoidBox( lua_State* L)
    return 1 ;
 }
 
-//----------------------------------------------------------------------------
-static int
-LuaVolZmapAvoidSphere( lua_State* L)
-{
-  // 4 o 5 parametri : nId, ptCen, dRad, dSafeDist [, nRefType]
-   int nId ;
-   LuaCheckParam( L, 1, nId)
-   Point3d ptCen ;
-   LuaCheckParam( L, 2, ptCen)
-   double dRad ;
-   LuaCheckParam( L, 3, dRad)
-   double dSafeDist ;
-   LuaCheckParam( L, 4, dSafeDist)
-   int nRefType = RTY_DEFAULT ;
-   LuaGetParam( L, 5, nRefType) ;
-   LuaClearStack( L) ;
-  // verifico non interferenza
-   bool bOk = ExeVolZmapAvoidSphere( nId, ptCen, dRad, dSafeDist, nRefType) ;
-  // restituisco il risultato
-   LuaSetParam( L, bOk) ;
-   return 1 ;
-}
-
 //----------------------------------------------------------------------------
 static int
 LuaVolZmapAvoidCylinder( lua_State* L)
@@ -427,6 +404,29 @@ LuaVolZmapAvoidCylinder( lua_State* L)
    return 1 ;
 }
 
+//----------------------------------------------------------------------------
+static int
+LuaVolZmapAvoidSphere( lua_State* L)
+{
+  // 4 o 5 parametri : nId, ptCen, dRad, dSafeDist [, nRefType]
+   int nId ;
+   LuaCheckParam( L, 1, nId)
+   Point3d ptCen ;
+   LuaCheckParam( L, 2, ptCen)
+   double dRad ;
+   LuaCheckParam( L, 3, dRad)
+   double dSafeDist ;
+   LuaCheckParam( L, 4, dSafeDist)
+   int nRefType = RTY_DEFAULT ;
+   LuaGetParam( L, 5, nRefType) ;
+   LuaClearStack( L) ;
+  // verifico non interferenza
+   bool bOk = ExeVolZmapAvoidSphere( nId, ptCen, dRad, dSafeDist, nRefType) ;
+  // restituisco il risultato
+   LuaSetParam( L, bOk) ;
+   return 1 ;
+}
+
 //----------------------------------------------------------------------------
 static int
 LuaCutVolZmapPlane( lua_State* L)
@@ -467,8 +467,8 @@ LuaInstallGdbModifyVol( LuaMgr& luaMgr)
    bOk = bOk && luaMgr.RegisterFunction( "EgtVolZmapMillingStep", LuaVolZmapMillingStep) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtVolZmapGetDepth", LuaVolZmapGetDepth) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtVolZmapAvoidBox", LuaVolZmapAvoidBox) ;
-   bOk = bOk && luaMgr.RegisterFunction( "EgtVolZmapAvoidSphere", LuaVolZmapAvoidSphere) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtVolZmapAvoidCylinder", LuaVolZmapAvoidCylinder) ;
+   bOk = bOk && luaMgr.RegisterFunction( "EgtVolZmapAvoidSphere", LuaVolZmapAvoidSphere) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtCutVolZmapPlane", LuaCutVolZmapPlane) ;
    return bOk ;
 }
\ No newline at end of file