diff --git a/LuaLibs/MachiningLib.lua b/LuaLibs/MachiningLib.lua
index 8f10250..4b097e8 100644
--- a/LuaLibs/MachiningLib.lua
+++ b/LuaLibs/MachiningLib.lua
@@ -241,6 +241,10 @@ local function FindMachining( MachiningType, sType, Params, bTopHead, bDownHead,
       bExcludeH3 = false
    end
    SetCurrMachineHeadType()
+   -- verifico se non richiesta testa sopra e macchina ha solo teste sopra
+   if not bTopHead and MachineHeadType ~= TWO_UP_DOWN_HEADS and not BD.TURN then
+      return nil
+   end
    -- verifico se testa attiva va bene
    local sH1Mach = ''
    local sH1Tool = ''
diff --git a/LuaLibs/ProcessLapJoint.lua b/LuaLibs/ProcessLapJoint.lua
index 136929b..4dd05e0 100644
--- a/LuaLibs/ProcessLapJoint.lua
+++ b/LuaLibs/ProcessLapJoint.lua
@@ -3683,13 +3683,17 @@ local function MakeByPockets( Proc, nPhase, nRawId, nPartId, nChamfer, dDepthCha
             sNotes = sNotes .. 'VMRS=0;'
             EgtSetMachiningParam( MCH_MP.USERNOTES, sNotes)
             -- eseguo
-            if not ML.ApplyMachining( true, false) then
+            if not ML.ApplyMachining( true, false) or EgtIsMachiningEmpty() then
                -- provo ad allargare leggermente la tasca
                EgtSetMachiningParam( MCH_MP.OFFSR, -0.1)
                if not ML.ApplyMachining( true, false) then
                   local _, sErr = EgtGetLastMachMgrError()
                   EgtSetOperationMode( nMchFId, false)
                   return -1, sErr
+               elseif EgtIsMachiningEmpty() then
+                  EgtRemoveOperation( nMchFId)
+                  local sErr = 'Impossible to machine (empty toolpath)'
+                  return -3, sErr
                end
             end
             -- se posso applicare la svuotatura sul lato opposto
@@ -5238,7 +5242,9 @@ local function MakeMoreFaces( Proc, nPhase, nRawId, nPartId, dOvmHead, bSinglePa
                            end
                            nOk, sErr, dDimMin, dDimMax, dDepth, vtOrtho, nLundIdFace, dDiamTool, bDoubleSide, nPathInt, nSurfInt, bOneShot, bMillDown, nFirstMachId, 
                            bOrthoFaces = MakeByPockets( Proc, nPhase, nRawId, nPartId, nChamfer, dDepthCham, nAddGrpId, sMyMchFind, bIs3Faces, b3Solid, bOrthoFacesMaster, bMillDown, bSetOpenBorders, bIsU, bIsL)
-                           if nOk == -2 then
+                           if nOk == -3 then
+                              bTryWithBlades = true
+                           elseif nOk == -2 then
                               if not sMchFind then 
                                  sMchFind = sMchFindBackUp 
                               end
diff --git a/LuaLibs/ProcessSplit.lua b/LuaLibs/ProcessSplit.lua
index 3737905..a7354bd 100644
--- a/LuaLibs/ProcessSplit.lua
+++ b/LuaLibs/ProcessSplit.lua
@@ -453,9 +453,9 @@ function ProcessSplit.Make( Proc, nPhase, nRawId, nPartId, nOrd, sDownOrSideOrSt
          local dSawRad = dSawDiam / 2
          local dKL = dSawRad - dMaxDepth + b3Raw:getDimY() / 2 + BD.CUT_EXTRA_MIN
          if BD.C_SIMM then
-            dAccEnd = sqrt( dSawRad * dSawRad - dKL * dKL)
+            dAccEnd = sqrt( max( dSawRad * dSawRad - dKL * dKL, 0))
          else
-            dAccStart = sqrt( dSawRad * dSawRad - dKL * dKL)
+            dAccStart = sqrt( max( dSawRad * dSawRad - dKL * dKL, 0))
          end
       end
       -- se necessari tagli in doppio, eseguo gli opposti