diff --git a/LuaLibs/ProcessLapJoint.lua b/LuaLibs/ProcessLapJoint.lua
index a649113..689bd1b 100644
--- a/LuaLibs/ProcessLapJoint.lua
+++ b/LuaLibs/ProcessLapJoint.lua
@@ -5673,7 +5673,6 @@ end
 local function MakeStaircaseStep( Proc, nRawId, b3Raw, b3Solid)
    -- angolo tra le facce
    local _, _, _, dAng = EgtSurfTmFacetsContact( Proc.Id, 0, 1, GDB_ID.ROOT)
-   local _, _, _, dAng2 = EgtSurfTmFacetsContact( Proc.Id, 1, 0, GDB_ID.ROOT)
    -- l'angolo tra le facce deve essere compreso tra 80 e 90.5 deg
    if ( dAng > -89.5 + 10 * GEO.EPS_ANG_SMALL) or ( dAng < -100 - 10 * GEO.EPS_ANG_SMALL) then return false end
    -- normali delle facce
@@ -5721,16 +5720,24 @@ local function MakeStaircaseStep( Proc, nRawId, b3Raw, b3Solid)
    local dSawMaxDepth = 0
    local dSawDiam = 400
    local dSawRotationSpeed = 0
+   local dSawThick = 5
    if sCutting then
       if EgtMdbSetCurrMachining( sCutting) then
          local sTuuid = EgtMdbGetCurrMachiningParam( MCH_MP.TUUID)
          if EgtTdbSetCurrTool( EgtTdbGetToolFromUUID( sTuuid) or '') then
             dSawMaxDepth = EgtTdbGetCurrToolMaxDepth() or dSawMaxDepth
-            dSawRotationSpeed = EgtMdbGetCurrMachiningParam( MCH_MP.SPEED)or dSawRotationSpeed
+            dSawRotationSpeed = EgtTdbGetCurrToolParam( MCH_MP.SPEED) or dSawRotationSpeed
+            dSawThick = EgtTdbGetCurrToolParam( MCH_TP.THICK) or dSawThick
          end
       end
    end
 
+   -- calcolo riduzione profondità lama in caso di angolo inferiore a 90deg
+   local dCutExtraSaw = 0
+   if dAng < -91 and dAng > -179 then
+      dCutExtraSaw = - dSawThick / tan( 180 + dAng)
+   end
+
    -- fresatura della pedata per fare spazio alla lama
    local dMillingDepth = dVTread - dSawMaxDepth + 10
    -- divido in passate orizzontali
@@ -5809,10 +5816,10 @@ local function MakeStaircaseStep( Proc, nRawId, b3Raw, b3Solid)
    end
    for i = 2, 1, -1 do
       -- inserisco la lavorazione della faccia
-      local dCutRadialOffsetTread = ( i - 1) * dSawMaxDepth / 2
+      local dCutRadialOffsetTread = - dSawMaxDepth / 2 * ( i - 1)
       -- componente limite del vettore Z per lama downUp; impostata a -2 per non farla mai rientrare in quel caso
       local dVzLimDwnUp = -2
-      local bOkSawTread, sErr = Fbs.MakeOne( Proc.Id, nFacetTread, sCutting, dSawDiam, nFaceUseTread, dVzLimDwnUp, -dCutRadialOffsetTread, 0, 0, 0, 0, nil, b3Raw)
+      local bOkSawTread, sErr = Fbs.MakeOne( Proc.Id, nFacetTread, sCutting, dSawDiam, nFaceUseTread, dVzLimDwnUp, dCutRadialOffsetTread + dCutExtraSaw, 0, 0, 0, 0, nil, b3Raw)
    end
 
    -- taglio di lama dell'alzata
@@ -5826,10 +5833,10 @@ local function MakeStaircaseStep( Proc, nRawId, b3Raw, b3Solid)
    end
    for i = nSawStepsRiser, 1, -1 do
       -- inserisco la lavorazione della faccia
-      local dCutRadialOffsetRiser = ( i - 1) * dSawStepRiser
+      local dCutRadialOffsetRiser = - dSawStepRiser * ( i - 1)
       -- componente limite del vettore Z per lama downUp; impostata a -2 per non farla mai rientrare in quel caso
       local dVzLimDwnUp = -2
-      local bOkSawRiser, sErr = Fbs.MakeOne( Proc.Id, nFacetRiser, sCutting, dSawDiam, nFaceUseRiser, dVzLimDwnUp, -dCutRadialOffsetRiser, 0, 0, 0, 0, nil, b3Raw)
+      local bOkSawRiser, sErr = Fbs.MakeOne( Proc.Id, nFacetRiser, sCutting, dSawDiam, nFaceUseRiser, dVzLimDwnUp, dCutRadialOffsetRiser + dCutExtraSaw, 0, 0, 0, 0, nil, b3Raw)
    end
 
 end