diff --git a/EgtMachKernel.rc b/EgtMachKernel.rc
index 5e80d3e..f55db0b 100644
Binary files a/EgtMachKernel.rc and b/EgtMachKernel.rc differ
diff --git a/MachineCalc.cpp b/MachineCalc.cpp
index 1a5cbb3..c0f15c5 100644
--- a/MachineCalc.cpp
+++ b/MachineCalc.cpp
@@ -93,17 +93,31 @@ Machine::SetCurrTool( const string& sTool, const string& sHead, int nExit)
    if ( pExit == nullptr)
       return false ;
   // recupero i dati dell'utensile
-   if ( ! LoadTool( sHead, nExit, sTool))
-      return false ;
-   int nToolId = m_pGeomDB->GetFirstNameInGroup( nExitId, sTool) ;
-   if ( nToolId == GDB_ID_NULL  ||  m_pGeomDB->GetGdbType( nToolId) != GDB_TY_GROUP)
-      return false ;
+   int nToolId = GDB_ID_NULL ;
    double dTLen = 0 ;
    double dTDiam = 0 ;
-   if ( ! m_pMchMgr->TdbSetCurrTool( sTool)  ||
-        ! m_pMchMgr->TdbGetCurrToolParam( TPA_LEN, dTLen)  ||
-        ! m_pMchMgr->TdbGetCurrToolParam( TPA_DIAM, dTDiam))
-      return false ;
+   // se definito
+   if ( ! sTool.empty()) {
+      if ( ! LoadTool( sHead, nExit, sTool))
+         return false ;
+      nToolId = m_pGeomDB->GetFirstNameInGroup( nExitId, sTool) ;
+      if ( nToolId == GDB_ID_NULL  ||  m_pGeomDB->GetGdbType( nToolId) != GDB_TY_GROUP)
+         return false ;
+      if ( ! m_pMchMgr->TdbSetCurrTool( sTool)  ||
+           ! m_pMchMgr->TdbGetCurrToolParam( TPA_LEN, dTLen)  ||
+           ! m_pMchMgr->TdbGetCurrToolParam( TPA_DIAM, dTDiam))
+         return false ;
+   }
+   // altrimenti casi speciali senza utensile
+   else {
+     // tolgo eventuale utensile dalla testa
+      if ( ! ResetHeadSet( sHead))
+         return false ;
+      nToolId = GDB_ID_NULL ;
+      dTLen = 0 ;
+      dTDiam = 0 ;
+      m_pMchMgr->TdbSetCurrTool( sTool) ;
+   }
   // assegno tutti i dati
    m_nCalcHeadId = nHeadId ;
    m_nCalcExitId = nExitId ;
diff --git a/MachineLua.cpp b/MachineLua.cpp
index 3fb36ba..5767828 100644
--- a/MachineLua.cpp
+++ b/MachineLua.cpp
@@ -352,9 +352,9 @@ Machine::LuaEmtStdHead( lua_State* L)
   // lettura campo 'TDir' dalla tabella
    Vector3d vtTDir ;
    LuaCheckTabFieldParam( L, 1, "TDir", vtTDir)
-  // lettura campo 'ADir' dalla tabella
+  // lettura eventuale campo 'ADir' dalla tabella
    Vector3d vtADir ;
-   LuaCheckTabFieldParam( L, 1, "ADir", vtADir)
+   LuaGetTabFieldParam( L, 1, "ADir", vtADir) ;
   // lettura eventuale campo 'Rot1W' dalla tabella (default 1)
    double dRot1W = 1 ;
    LuaGetTabFieldParam( L, 1, "Rot1W", dRot1W) ;
@@ -420,7 +420,7 @@ Machine::LuaEmtMultiHead( lua_State* L)
    }
   // lettura campo 'ADir' dalla tabella
    Vector3d vtADir ;
-   LuaCheckTabFieldParam( L, 1, "ADir", vtADir)
+   LuaGetTabFieldParam( L, 1, "ADir", vtADir) ;
   // lettura eventuale campo 'Rot1W' dalla tabella (default 1)
    double dRot1W = 1 ;
    LuaGetTabFieldParam( L, 1, "Rot1W", dRot1W) ;
diff --git a/ToolsMgr.cpp b/ToolsMgr.cpp
index 5efe195..91c8837 100644
--- a/ToolsMgr.cpp
+++ b/ToolsMgr.cpp
@@ -467,6 +467,11 @@ ToolsMgr::VerifyTool( int nFamily, string& sName, int& nType) const
 bool
 ToolsMgr::SetCurrTool( const std::string& sName)
 {
+  // se nome vuoto, faccio reset
+   if ( sName.empty()) {
+      m_bCurrTool = false ;
+      return false ;
+   }
   // recupero i dati dell'utensile
    const ToolData* ptData = GetTool( sName) ;
    if ( ptData == nullptr) {