diff --git a/LuaLibs/PreSimulationLib.lua b/LuaLibs/PreSimulationLib.lua
index c4c75d6..7a6d6c0 100644
--- a/LuaLibs/PreSimulationLib.lua
+++ b/LuaLibs/PreSimulationLib.lua
@@ -41,20 +41,11 @@ local function LogOutstroke( sToolName, ptOnToolTipCenter, vtHead, OptionalParam
    local LinearAxesValues = OptionalParameters.LinearAxesValues
    local RotativeAxesValues = OptionalParameters.RotativeAxesValues
 
-   -- gruppo per geometrie temporanee
-   local idTempGroup = BeamLib.GetTempGroup()
-
-   -- si disegnano punto e vettore
-   local idPoint = EgtPoint( idTempGroup, ptOnToolTipCenter, GDB_RT.GLOB)
-   local idVector = EgtVector( idTempGroup, vtHead, ptOnToolTipCenter, GDB_RT.GLOB)
-   EgtSetColor( idPoint, RED())
-   EgtSetColor( idVector, RED())
-
    -- nome utensile
    EgtOutLog( 'Tool ' .. sToolName)
 
    -- si loggano valori di punto e vettore
-   EgtOutLog( ' Presimulation : OutStroke, Tip Point = ' .. tostring( ptOnToolTipCenter) .. ', id = ' .. idPoint .. ', vtHead = ' .. tostring( vtHead) .. ', id = ' .. idVector)
+   EgtOutLog( ' Presimulation : OutStroke, Tip Point = ' .. tostring( ptOnToolTipCenter) .. ', vtHead = ' .. tostring( vtHead))
 
    -- se disponibili, si loggano anche i valori calcolati degli assi
    if LinearAxesValues then
@@ -348,20 +339,23 @@ local function CheckCollisionPoint( sAxis, ptOnToolTipCenter, vtHead, vtAux, Par
       if not type( bCollisionFoundPiece) == "boolean" then
          error( 'Presimulation fail')
       end
-      if EgtGetDebugLevel() >= 3 and bCollisionFoundPiece then
-         EgtSetColor( CollisionSurfTmId[i], RED())
-      end
       if bCollisionFoundPiece then
          break
       end
    end
 
-      -- se trovata collisione con pezzo è inutile procedere con il grezzo
-      if bCollisionFoundPiece then
+   -- se trovata collisione con pezzo è inutile procedere con il grezzo
+   if bCollisionFoundPiece then
 
-         return true
+      for i = 1, #CollisionSurfTmId do
+         if CollisionSurfTmId[i] ~= idAddedCollisionSurfTm then
+            EgtErase( CollisionSurfTmId[i])
+         end
       end
 
+      return true
+   end
+
    -- check collisione con grezzo restante, se con il pezzo non c'è collisione e non è un taglio di testa o coda
    local bCollisionFoundRestLength = false
    if not ( bCollisionFoundPiece or bCannotSplitRestLength) then
@@ -372,14 +366,19 @@ local function CheckCollisionPoint( sAxis, ptOnToolTipCenter, vtHead, vtAux, Par
             if not type( bCollisionFoundRestLength) == "boolean" then
                error( 'Presimulation fail')
             end
-            if EgtGetDebugLevel() >= 3 and bCollisionFoundRestLength then
-               EgtSetColor( CollisionSurfTmId[i], ORANGE())
-            end
             if bCollisionFoundRestLength then
+               EgtErase( idRestLengthSurfFr)
                break
             end
          end
       end
+      EgtErase( idRestLengthSurfFr)
+   end
+
+   for i = 1, #CollisionSurfTmId do
+      if CollisionSurfTmId[i] ~= idAddedCollisionSurfTm then
+         EgtErase( CollisionSurfTmId[i])
+      end
    end
 
    return false, bCollisionFoundRestLength
@@ -429,6 +428,7 @@ local function CheckCollisionWithAxis( sAxis, MachiningParameters, OptionalParam
       if Tool.sType == 'SAW_FLAT' then
          local ptCenterFlange = PointsOnToolTipCenter[i] + vtHead * Tool.dThickness
          local frHead = Frame3d( ptCenterFlange, vtHead)
+         EgtErase( ptCenterFlange)
          local dExtraSafety = 2 -- valore empirico che serve nei casi molto inclinati, ci potrebbero essere casi in cui va aumentato
          local idFlangeCurve = EgtCircle( Part.idTempGroup, ORIG(), dExtraSafety + Tool.dDiameter / 2 - Tool.dMaxDepth, GDB_RT.GLOB)
          EgtTransform( idFlangeCurve, frHead, GDB_RT.GLOB)
@@ -440,10 +440,13 @@ local function CheckCollisionWithAxis( sAxis, MachiningParameters, OptionalParam
          
          local vtExtrusion = 15 * vtHead
          idAddedCollisionSurfTm = EgtSurfTmByRegionExtrusion( Part.idTempGroup, idFlangeCurve, vtExtrusion, 0.05, GDB_RT.GLOB)
+         EgtErase( idFlangeCurve)
       end
 
       local bCollisionFoundPiece, bCollisionFoundRestLength = CheckCollisionPoint( sAxis, PointsOnToolTipCenter[i], vtHead, vtAux, Part, bCannotSplitRestLength, sRestLengthSideForPreSimulation, idCheckCollisionTm, idAddedCollisionSurfTm)
 
+      EgtErase( idAddedCollisionSurfTm)
+
       -- se trovata collisione con pezzo è inutile controllare gli altri punti
       if bCollisionFoundPiece then
 
diff --git a/StrategyLibs/BLADETOWASTE.lua b/StrategyLibs/BLADETOWASTE.lua
index 2afb658..13b9a5c 100644
--- a/StrategyLibs/BLADETOWASTE.lua
+++ b/StrategyLibs/BLADETOWASTE.lua
@@ -992,6 +992,8 @@ local function CalculateDiceMachinings( vCuts, Parameters)
       end
    end
 
+   EgtErase( idCheckCollisionTm)
+
    return true, Machinings, bMoveAfterSplit
 end