diff --git a/MachiningsDbWindow/MachiningTreeView.vb b/MachiningsDbWindow/MachiningTreeView.vb
index 8cb9c95..3ab15fe 100644
--- a/MachiningsDbWindow/MachiningTreeView.vb
+++ b/MachiningsDbWindow/MachiningTreeView.vb
@@ -1765,6 +1765,10 @@ Public Class MachiningTreeViewItem
    Private Shared ReadOnly ValidatedProperties() As String = {"Speed", "NamePar"}
 
    Private Function GetValidationError(ByVal propertyName As String) As String
+
+      If Not EgtCAM5.MachiningsDbViewModel.m_bActive Then
+         Return Nothing
+      End If
       If Array.IndexOf(ValidatedProperties, propertyName) < 0 Then
          Return Nothing
       End If
diff --git a/MachiningsDbWindow/MachiningsDbViewModel.vb b/MachiningsDbWindow/MachiningsDbViewModel.vb
index b504ad6..afa6978 100644
--- a/MachiningsDbWindow/MachiningsDbViewModel.vb
+++ b/MachiningsDbWindow/MachiningsDbViewModel.vb
@@ -8,6 +8,8 @@ Namespace EgtCAM5
    Public Class MachiningsDbViewModel
       Inherits TabViewModel
 
+      Friend Shared m_bActive As Boolean = False
+
       Private m_Title As String
       Public ReadOnly Property Title As String
          Get
@@ -336,6 +338,8 @@ Namespace EgtCAM5
       ''' </summary>
       Sub New()
 
+         m_bActive = True
+
          LoadSelectedMachineMachinings()
 
          Application.Msn.Register(Application.REMOVEMACHINING, Sub(MachiningToRemove As MachiningTreeViewItem)
@@ -633,6 +637,7 @@ Namespace EgtCAM5
       ''' Manage the MachiningDb closing.  This method is invoked by the CloseMachiningDbCommand.
       ''' </summary>
       Public Sub CloseMachiningsDb(param As Object)
+         m_bActive = False
          ' Se selezionata una lavorazione, verifico salvataggio
          If TypeOf param Is MachiningTreeViewItem Then
             Dim CurrMachining As MachiningTreeViewItem = DirectCast(param, MachiningTreeViewItem)
diff --git a/ToolsDbWindow/ToolTreeView.vb b/ToolsDbWindow/ToolTreeView.vb
index cc6e016..5975cf7 100644
--- a/ToolsDbWindow/ToolTreeView.vb
+++ b/ToolsDbWindow/ToolTreeView.vb
@@ -1269,6 +1269,10 @@ Public Class ToolTreeViewItem
    Private Shared ReadOnly ValidatedProperties() As String = {"Draw", "MaxMat", "Thick", "Diam", "Len", "TotLen", "Speed", "NamePar"}
 
    Private Function GetValidationError(ByVal propertyName As String) As String
+
+      If Not EgtCAM5.ToolsDbViewModel.m_bActive Then
+         Return Nothing
+      End If
       If Array.IndexOf(ValidatedProperties, propertyName) < 0 Then
          Return Nothing
       End If
@@ -1374,7 +1378,7 @@ Public Class ToolTreeViewItem
             If Not IsNothing(m_MaxMat) Then
                Dim dMaxMat As Double = 0
                StringToLen(m_MaxMat, dMaxMat)
-               If (dDiam / 3) < dMaxMat Then
+               If (dDiam / 3) + EPS_SMALL < dMaxMat Then
                   Return EgtMsg(MSG_TOOLSERRORS + 19)
                End If
             End If
diff --git a/ToolsDbWindow/ToolsDbViewModel.vb b/ToolsDbWindow/ToolsDbViewModel.vb
index fff7914..d6c878c 100644
--- a/ToolsDbWindow/ToolsDbViewModel.vb
+++ b/ToolsDbWindow/ToolsDbViewModel.vb
@@ -10,6 +10,8 @@ Namespace EgtCAM5
    Public Class ToolsDbViewModel
       Inherits TabViewModel
 
+      Friend Shared m_bActive As Boolean = False
+
       Private m_Title As String
       Public ReadOnly Property Title As String
          Get
@@ -230,6 +232,9 @@ Namespace EgtCAM5
       ''' Constructor
       ''' </summary>
       Sub New()
+
+         m_bActive = True
+
          ' leggo direttorio toolmakers
          GetPrivateProfileString(S_MACH, K_TOOLMAKERSDIR, "", IniFile.m_sToolMakersDir)
 
@@ -561,6 +566,7 @@ Namespace EgtCAM5
       ''' Manage the MachiningDb closing.  This method is invoked by the CloseMachiningDbCommand.
       ''' </summary>
       Public Sub CloseToolsDb(param As Object)
+         m_bActive = False
          ' Imposto contesto di progetto
          EgtSetCurrentContext(IniFile.m_ProjectSceneContext)
          ' Se selezionata una lavorazione, verifico salvataggio