diff --git a/LuaLibs/BeamLib.lua b/LuaLibs/BeamLib.lua
index 5719ac6..37db86a 100644
--- a/LuaLibs/BeamLib.lua
+++ b/LuaLibs/BeamLib.lua
@@ -299,6 +299,7 @@ function BeamLib.CreateTempGroup()
    if not idTempGroup then
       idTempGroup = EgtGroup( GDB_ID.ROOT)
       EgtSetName( idTempGroup, "#TEMP_GROUP#")
+      EgtSetColor( idTempGroup, Color3d( 80, 160, 160, 1))
       EgtSetLevel( idTempGroup, GDB_LV.TEMP)
    end
    return idTempGroup
diff --git a/LuaLibs/PreCollisionLib.lua b/LuaLibs/PreCollisionLib.lua
index 63bf790..381fc78 100644
--- a/LuaLibs/PreCollisionLib.lua
+++ b/LuaLibs/PreCollisionLib.lua
@@ -86,11 +86,11 @@ local function GetMachiningPoints( Edge, dDepthToMachine)
 
    -- aggiunta punti
    -- inizio e fine solo se lato obliquo
-   if bIsEdgeParallelToMainDirection then
+   if not bIsEdgeParallelToMainDirection then
       table.insert( MachiningPoints, ptStart)
    end
    table.insert( MachiningPoints, ptMid)
-   if bIsEdgeParallelToMainDirection then
+   if not bIsEdgeParallelToMainDirection then
       table.insert( MachiningPoints, ptEnd)
    end
 
@@ -133,10 +133,6 @@ function PreCollisionLib.CheckCollisionAxisZ( Edge, vtNFace, vtHead, Part, Tool,
       { vtDirectionX = X_AX(), vtDirectionY = Y_AX(), vtDirectionZ = Z_AX(), sDirectionName = 'Z'}
    }
       
-   -- TEST
-   local Color = Color3d( math.random(0, 255), math.random(0, 255), math.random(0, 255))
-   -- TEST
-
    local bMoveAfterSplit = false
 
    -- nel singolo punto notevole si ha collisione se si trova intersezione in tutte le direzioni
@@ -162,9 +158,6 @@ function PreCollisionLib.CheckCollisionAxisZ( Edge, vtNFace, vtHead, Part, Tool,
          local CollisionCurvePoints = Tool.SetupInfo.GetAxisPoints( 'Z', sDirectionName)
          -- curva di collisione in riferimento locale
          local idCollisionCurve = EgtCurveCompoFromPoints( Part.idTempGroup, CollisionCurvePoints)
-         -- TEST
-         EgtSetColor( idCollisionCurve, Color)
-         -- TEST
          -- curva in riferimento globale
          local frReference = Frame3d( ptPivot, vtDirectionZ, vtDirectionX)
          EgtTransform( idCollisionCurve, frReference, GDB_RT.GLOB )
@@ -177,24 +170,16 @@ function PreCollisionLib.CheckCollisionAxisZ( Edge, vtNFace, vtHead, Part, Tool,
          local bCollisionFoundPiece = false
          if nCollisionCountPiece == j - 1 then
             local idPartSurfFr = GetPartSurfFrInPlane( Part, vtDirectionZ)
-            local bIntersectSuccess = EgtSurfFrIntersect( idPartSurfFr, idCollisionSurfFr)
-            if not bIntersectSuccess then
-               error( 'CheckCollision : intersect fail')
-            end
 
-            bCollisionFoundPiece = EgtExistsObj( idPartSurfFr)
+            bCollisionFoundPiece = not EgtSurfFrTestExternal( idPartSurfFr, idCollisionSurfFr)
          end
 
          -- check collisione con grezzo restante, se con il pezzo non c'è collisione
          local bCollisionFoundRestLength = false
          if not bCollisionFoundPiece then
             local idRestLengthSurfFr = GetRestlengthSurfFrInPlane( Part, vtDirectionZ)
-            local bIntersectSuccess = EgtSurfFrIntersect( idRestLengthSurfFr, idCollisionSurfFr)
-            if not bIntersectSuccess then
-               error( 'CheckCollision : intersect fail')
-            end
 
-            bCollisionFoundRestLength = EgtExistsObj( idRestLengthSurfFr)
+            bCollisionFoundRestLength = not EgtSurfFrTestExternal( idRestLengthSurfFr, idCollisionSurfFr)
          end
 
          -- se non trovata collisione si passa al punto successivo
@@ -262,31 +247,13 @@ function PreCollisionLib.CheckCollisionAxisAB( Edge, vtNFace, vtHead, Part, Tool
    -- flat region dal rettangolo
    local idHeadSurfFr = EgtSurfFlatRegion( Part.idTempGroup, idHeadRectangle)
 
-   -- intersezione tra pezzo e motore (se fallisce si inverte la flat region del motore, probabile normale opposta)
-   local bIntersectSuccess = EgtSurfFrIntersect( idPartSurfFr, idHeadSurfFr)
-   if not bIntersectSuccess then
-      EgtInvertSurf( idHeadSurfFr)
-      bIntersectSuccess = EgtSurfFrIntersect( idPartSurfFr, idHeadSurfFr)
-   end
-   if not bIntersectSuccess then
-      error( 'Check2DBladeCollision : intersect fail')
-   end
-
-   local bCollisionFoundPiece = EgtExistsObj( idPartSurfFr)
+   -- intersezione tra pezzo e motore
+   local bCollisionFoundPiece = not EgtSurfFrTestExternal( idPartSurfFr, idHeadSurfFr)
 
    -- intersezione tra grezzo restante e motore, se con il pezzo non c'è collisione
    local bCollisionFoundRestLength
    if not bCollisionFoundPiece then
-      bIntersectSuccess = EgtSurfFrIntersect( idRestlengthSurfFr, idHeadSurfFr)
-      if not bIntersectSuccess then
-         EgtInvertSurf( idHeadSurfFr)
-         bIntersectSuccess = EgtSurfFrIntersect( idRestlengthSurfFr, idHeadSurfFr)
-      end
-      if not bIntersectSuccess then
-         error( 'Check2DBladeCollision : intersect fail')
-      end
-
-      bCollisionFoundRestLength = EgtExistsObj( idRestlengthSurfFr)
+      bCollisionFoundRestLength = not EgtSurfFrTestExternal( idRestlengthSurfFr, idHeadSurfFr)
    end
 
    return bCollisionFoundPiece, bCollisionFoundRestLength