diff --git a/LuaLibs/ProcessDrill.lua b/LuaLibs/ProcessDrill.lua
index cf836ab..04d512a 100644
--- a/LuaLibs/ProcessDrill.lua
+++ b/LuaLibs/ProcessDrill.lua
@@ -394,7 +394,8 @@ function ProcessDrill.Make( Proc, nPhase, nRawId, nPartId)
    EgtSetMachiningParam( MCH_MP.SCC, nSCC)
    -- aggiusto l'affondamento
    local sMyWarn
-   local dMaxElev = dLen
+   local dMaxElev = dDepth
+   local dToolAddLength = 0
    -- se c'è un taglio precedente di testa o coda posso impostare MaxElev per allungare il percorso
    -- considero solo i fori "entranti" in testa o coda
    if ( Proc.MachineAfterHeadCutId and vtExtr:getX() > 0) or ( Proc.MachineAfterTailCutId and vtExtr:getX() < 0) then
@@ -408,14 +409,15 @@ function ProcessDrill.Make( Proc, nPhase, nRawId, nPartId)
          elseif dHoleToCutDistance < 0 then
             dMaxElev = -dHoleToCutDistance
          end
+         dToolAddLength = dLen - dMaxElev
       end
    end
-   local dToolAddLength = dLen - dMaxElev
    if dDepth - dToolAddLength > dMaxDepth + 10 * GEO.EPS_SMALL then
       sMyWarn = 'Warning in drill : depth (' .. EgtNumToString( dDepth - dToolAddLength, 1) .. ') bigger than max tool depth (' .. EgtNumToString( dMaxDepth, 1) .. ')'
-      if dMaxDepth == 0 then
-         dDepth = 0
-      else
+      if dMaxDepth == 0 or dToolAddLength == 0 then
+         dDepth = dMaxDepth
+         dMaxElev = dDepth
+      elseif abs( dMaxElev - dDepth) > GEO.EPS_SMALL then
          dDepth = dLen
       end
       EgtOutLog( sMyWarn)