diff --git a/LuaLibs/WProcessLapJoint.lua b/LuaLibs/WProcessLapJoint.lua
index 16d1e63..7f55d70 100644
--- a/LuaLibs/WProcessLapJoint.lua
+++ b/LuaLibs/WProcessLapJoint.lua
@@ -1443,6 +1443,8 @@ local function MakeSideGrooveByMill( Proc, nFacet, nRawId, b3Raw, sCustomMach, d
       EgtOutLog( sErr)
       return false, sErr
    end
+   local dGrooveMinZ = max( b3Raw:getMin():getZ(), Proc.Box:getMin():getZ())
+   local dRawMaxZ = b3Raw:getMax():getZ()
    -- recupero i dati dell'utensile
    local dMillDiam = 20
    local dMillLen = 10
@@ -1472,8 +1474,6 @@ local function MakeSideGrooveByMill( Proc, nFacet, nRawId, b3Raw, sCustomMach, d
                dMaxDepthOnSide = EgtTdbGetCurrToolValInNotes( MCH_TP.USERNOTES, 'SIDEDEPTH', 'd')
             end
          end
-         local dGrooveMinZ = max( b3Raw:getMin():getZ(), Proc.Box:getMin():getZ())
-         local dRawMaxZ = b3Raw:getMax():getZ()
          -- se riesco a lavorare il sottosquadro senza arrivare alla parte larga del portautensile uso la sidedepth o il diametro stretto del portautensile come diametro del gambo
          if ( dMillTotLen - dMillLenTh) > ( abs( dRawMaxZ - dGrooveMinZ) + 1) then
             if dMaxDepthOnSide and dMaxDepthOnSide > 0 then
@@ -1497,7 +1497,13 @@ local function MakeSideGrooveByMill( Proc, nFacet, nRawId, b3Raw, sCustomMach, d
       return false, sErr
    end
    if Proc.Fct == 2 and Proc.Box:getMin():getZ() < b3Raw:getMin():getZ() + 100 * GEO.EPS_SMALL and dMaxMat > dThick + 10 * GEO.EPS_SMALL then
-       local sErr = 'Error : Tool thickness is too big'
+      local sErr = 'Error : Tool thickness is too big'
+      EgtOutLog( sErr)
+      return false, sErr
+   end
+   -- se la testa scende sotto al limite superiore del grezzo
+   if dMillTotLen < ( abs( dRawMaxZ - dGrooveMinZ) + 1) then
+      local sErr = 'Error : Tool too short, head will collide with rawpart'
       EgtOutLog( sErr)
       return false, sErr
    end