diff --git a/EXE_GdbCreateSurf.cpp b/EXE_GdbCreateSurf.cpp
index 530b0dd..962e87b 100644
--- a/EXE_GdbCreateSurf.cpp
+++ b/EXE_GdbCreateSurf.cpp
@@ -1082,7 +1082,7 @@ ExeCreateSurfTmByRevolve( int nParentId, int nCrvId,
 int
 ExeCreateSurfTmByScrewing( int nParentId, int nCrvId,
                            const Point3d& ptAx, const Vector3d& vtAx,
-                           double dAngRotDeg, double dMove, double dLinTol, int nRefType)
+                           double dAngRotDeg, double dMove, bool bCapEnds, double dLinTol, int nRefType)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
    VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
@@ -1098,7 +1098,7 @@ ExeCreateSurfTmByScrewing( int nParentId, int nCrvId,
    Point3d ptAxL = GetPointLocal( pGeomDB, ptAx, nRefType, frLoc) ;
    Vector3d vtAxL = GetVectorLocal( pGeomDB, vtAx, nRefType, frLoc) ;
   // calcolo la superficie
-   ISurfTriMesh* pSTM = ( bOk ? GetSurfTriMeshByScrewing( CrvLoc, ptAxL, vtAxL, dAngRotDeg, dMove, dLinTol) : nullptr) ;
+   ISurfTriMesh* pSTM = ( bOk ? GetSurfTriMeshByScrewing( CrvLoc, ptAxL, vtAxL, dAngRotDeg, dMove, bCapEnds, dLinTol) : nullptr) ;
   // inserisco la superficie nel DB
    int nNewId = ( bOk ? pGeomDB->AddGeoObj( GDB_ID_NULL, nParentId, pSTM) : GDB_ID_NULL) ;
    ExeSetModified() ;
@@ -1110,6 +1110,7 @@ ExeCreateSurfTmByScrewing( int nParentId, int nCrvId,
                                              ToString( vtAx) + "}," +
                                              ToString( dAngRotDeg) + "," +
                                              ToString( dMove) + "," +
+                                             ( bCapEnds ? "true" : "false") + "," +
                                              ToString( dLinTol) + "," +
                                              RefTypeToString( nRefType) + ")" +
                     " -- Id=" + ToString( nNewId) ;
diff --git a/LUA_GdbCreateSurf.cpp b/LUA_GdbCreateSurf.cpp
index 7792d28..0cf7cdd 100644
--- a/LUA_GdbCreateSurf.cpp
+++ b/LUA_GdbCreateSurf.cpp
@@ -529,7 +529,7 @@ LuaCreateSurfTmByRevolve( lua_State* L)
 static int
 LuaCreateSurfTmByScrewing( lua_State* L)
 {
-  // 6 o 7 o 8 parametri : ParentId, CrvId, ptAx, vtAx, dAngRotDeg, dMove [, dTol] [, nRefType]
+  // 6 o 7 o 8 o 9 parametri : ParentId, CrvId, ptAx, vtAx, dAngRotDeg, dMove [, bCapEnds] [, dTol] [, nRefType]
    int nParentId ;
    LuaCheckParam( L, 1, nParentId)
    int nCrvId ;
@@ -542,15 +542,19 @@ LuaCreateSurfTmByScrewing( lua_State* L)
    LuaCheckParam( L, 5, dAngRotDeg)
    double dMove ;
    LuaCheckParam( L, 6, dMove)
+   int nPar = 7 ;
+   bool bCapEnds = false ;
+   if ( LuaGetParam( L, nPar, bCapEnds))
+      ++ nPar ;
    double dLinTol = LIN_TOL_DEF ;
+   if ( LuaGetParam( L, nPar, dLinTol))
+      ++ nPar ;
    int nRefType = RTY_DEFAULT ;
-   if ( LuaGetParam( L, 7, dLinTol))
-      LuaGetParam( L, 8, nRefType) ;
-   else
-      LuaGetParam( L, 7, nRefType) ;
+   if ( LuaGetParam( L, nPar, nRefType))
+      ++ nPar ;
    LuaClearStack( L) ;
   // creo STM riempiendo un contorno piano
-   int nId = ExeCreateSurfTmByScrewing( nParentId, nCrvId, ptAx, vtAx, dAngRotDeg, dMove, dLinTol, nRefType) ;
+   int nId = ExeCreateSurfTmByScrewing( nParentId, nCrvId, ptAx, vtAx, dAngRotDeg, dMove, bCapEnds, dLinTol, nRefType) ;
   // restituisco il risultato
    if ( nId != GDB_ID_NULL)
       LuaSetParam( L, nId) ;