diff --git a/LuaLibs/ProcessLapJoint.lua b/LuaLibs/ProcessLapJoint.lua
index d62c3ba..b4c35f7 100644
--- a/LuaLibs/ProcessLapJoint.lua
+++ b/LuaLibs/ProcessLapJoint.lua
@@ -775,6 +775,10 @@ function ProcessLapJoint.IsTailFeature( Proc, b3Raw)
          return false
       end
    end
+   -- se forzata lavorazione con lama e feature aperta sulla coda potrei lavorare anche dalla coda
+   if Proc.AffectedFaces.Left and ( EgtGetInfo( Proc.Id, Q_SAW_PLUS_CHAIN, 'i') or 0) > 0 then
+      return true
+   end
    -- deve avere la normale principale diretta verso la coda (oppure tunnel)
    Topology.Classify( Proc, b3Raw)
    local nFacInd, dElev, nFacInd2, dElev2 = BL.GetFaceWithMostAdj( Proc, nPartId)
@@ -4866,8 +4870,13 @@ function SawPlusChain.CalculateLeadInOut( Machining, EdgeToMachine)
       LeadOut.Type = MCH_MILL_LI.LINEAR
       LeadIn.TangentDistance = 0
       LeadOut.TangentDistance = 0
-      LeadIn.PerpDistance = EdgeToMachine.Elevation + BD.CUT_SIC
-      LeadOut.PerpDistance = EdgeToMachine.Elevation + BD.CUT_SIC
+      if EdgeToMachine.Elevation > -10 * GEO.EPS_SMALL then
+         LeadIn.PerpDistance = EdgeToMachine.Elevation + BD.CUT_SIC
+         LeadOut.PerpDistance = EdgeToMachine.Elevation + BD.CUT_SIC
+      else
+         LeadIn.PerpDistance = BD.CUT_SIC
+         LeadOut.PerpDistance = BD.CUT_SIC
+      end
       LeadIn.Elevation = 0
       LeadOut.Elevation = 0
       LeadIn.CompLength = 0
@@ -5057,6 +5066,9 @@ function SawPlusChain.Saw.CalculateMachiningParameters( Proc, FaceToMachine, Edg
       Cutting.Workside = MCH_MILL_WS.LEFT
       Cutting.Invert = false
    end
+   if EdgeToMachine.Elevation < -10 * GEO.EPS_SMALL then
+      Cutting.Invert = not Cutting.Invert
+   end
    -- TODO gestire lama da sotto e lama downUp
    if FaceToMachine.VtN:getZ() < - 10 * GEO.EPS_SMALL then
       Cutting.ToolInvert = true
@@ -5065,14 +5077,22 @@ function SawPlusChain.Saw.CalculateMachiningParameters( Proc, FaceToMachine, Edg
       Cutting.ToolInvert = false
    end
    -- profondità e offset radiale
-   -- TODO gestire elevazione negativa (determina come devo lavorare)
    if Cutting.Tool.MaxDepth > abs( EdgeToMachine.Elevation) - 10 * GEO.EPS_SMALL then
+      -- TODO la depth dovrebbe essere quella del machining
       Cutting.Depth = abs( EdgeToMachine.Elevation)
-      Cutting.RadialOffset = 0
+      if EdgeToMachine.Elevation > -10 * GEO.EPS_SMALL then
+         Cutting.RadialOffset = 0
+      else
+         Cutting.RadialOffset = EdgeToMachine.Elevation
+      end
    else
       Cutting.Depth = Cutting.Tool.MaxDepth
-      Cutting.RadialOffset = abs( EdgeToMachine.Elevation) - Cutting.Depth
-      if SawPlusChain.ApplyOnlySawblade then
+      if EdgeToMachine.Elevation > -10 * GEO.EPS_SMALL then
+         Cutting.RadialOffset = EdgeToMachine.Elevation - Cutting.Depth
+      else
+         Cutting.RadialOffset = -Cutting.Depth
+      end
+      if EdgeToMachine.Elevation > -10 * GEO.EPS_SMALL and SawPlusChain.ApplyOnlySawblade then
          Cutting.Message = 'Feature '.. Proc.FeatureId .. ' : sawblade elevation (' .. EgtNumToString( EdgeToMachine.Elevation, 1) .. ') bigger than max tool depth (' .. EgtNumToString( Cutting.Depth, 1) .. ')'
          EgtOutLog( Cutting.Message)
       end
@@ -5264,6 +5284,7 @@ end
 
 
 function SawPlusChain.Make( bOnlySaw, Proc, nRawId)
+   SawPlusChain.ApplyOnlySawblade = bOnlySaw
    local b3Raw = EgtGetRawPartBBox( nRawId)
 
    -- TODO per implementare la strategia con lapjoint lunghe bisogna prima riconoscere le topologie che arrivano