diff --git a/LuaLibs/ProcessLapJoint.lua b/LuaLibs/ProcessLapJoint.lua
index 013c64e..fcecf32 100644
--- a/LuaLibs/ProcessLapJoint.lua
+++ b/LuaLibs/ProcessLapJoint.lua
@@ -5730,14 +5730,14 @@ local function MakeStaircaseStep( Proc, nRawId, b3Raw, b3Solid)
    end
 
    -- fresatura pedata per fare spazio alla lama
-   local dMillingDepth = dVTread - dSawMaxDepth + dMillDiam/2 - 10
+   local dMillingDepth = dVTread - dSawMaxDepth + 10
    -- divido in passate orizzontali
-   local nHorizontalStepMilling = ceil( ( dMillingDepth - 100 * GEO.EPS_SMALL) / ( dMillDiam * 0.6))
-   local dHorizontalStepMilling = 0
-   if nHorizontalStepMilling > 1 then
-      dHorizontalStepMilling = ( dMillingDepth - dMillDiam * 0.6) / ( nHorizontalStepMilling - 1)
+   local nMillHorizontalSteps = ceil( ( dMillingDepth - 100 * GEO.EPS_SMALL) / ( dMillDiam * 0.6))
+   local dMillHorizontalStep = 0
+   if nMillHorizontalSteps > 1 then
+      dMillHorizontalStep = ( dMillingDepth - dMillDiam * 0.6) / ( nMillHorizontalSteps - 1)
    end
-   for i = nHorizontalStepMilling, 1, -1 do
+   for i = nMillHorizontalSteps, 1, -1 do
       -- inserisco la lavorazione
       local sName = 'Mill_' .. ( EgtGetName( Proc.Id) or tostring( Proc.Id))
       local nMchFId = EgtAddMachining( sName, sMilling)
@@ -5777,7 +5777,7 @@ local function MakeStaircaseStep( Proc, nRawId, b3Raw, b3Solid)
          EgtSetMachiningParam( MCH_MP.LOPERP, 0)
       end
       -- imposto eventuale offset
-      EgtSetMachiningParam( MCH_MP.OFFSR, dVTread - dMillingDepth + i * dHorizontalStepMilling)
+      EgtSetMachiningParam( MCH_MP.OFFSR, dVTread - dMillingDepth + ( i - 1) * dMillHorizontalStep)
       -- se step verticale non presente, lo setto
       local dVerticalStepMilling = EgtGetMachiningParam( MCH_MP.STEP, 'd')
       if not dVerticalStepMilling or dVerticalStepMilling <= 10 * GEO.EPS_SMALL then