diff --git a/LuaLibs/FeatureTopology.lua b/LuaLibs/FeatureTopology.lua
index 03dbd55..5a3a09d 100644
--- a/LuaLibs/FeatureTopology.lua
+++ b/LuaLibs/FeatureTopology.lua
@@ -199,9 +199,12 @@ function FeatureTopology.Classify( Proc, b3Raw)
    elseif Proc.Fct == 2 and bAllAnglesConcave and #vTriangularFaces == 1 then
       sFamily = 'Bevel'
       bIsThrough = false
-   elseif Proc.Fct == 2 and bAllAnglesConcave then
+   elseif Proc.Fct == 2 and bAllAnglesConcave and ( Proc.AffectedFaces.Left or Proc.AffectedFaces.Right) and ( Proc.AffectedFaces.Front or Proc.AffectedFaces.Back) then
       sFamily = 'Rabbet'
       bIsThrough = true
+   elseif Proc.Fct == 2 and bAllAnglesConcave then
+      sFamily = 'Groove'
+      bIsThrough = true
    elseif Proc.Fct == 2 and not bAllAnglesConcave and bIsAnyDimensionLongAsPart then
       sFamily = 'DoubleBevel'
       bIsThrough = true
diff --git a/LuaLibs/ProcessLapJoint.lua b/LuaLibs/ProcessLapJoint.lua
index b1d4d58..4057728 100644
--- a/LuaLibs/ProcessLapJoint.lua
+++ b/LuaLibs/ProcessLapJoint.lua
@@ -151,6 +151,7 @@ local function AssignQIdent( Proc)
    Q_SIDE_ROUGH_TOOL    = ''
    Q_ANTISPLINT_TYPE    = ''
    Q_MAX_ELEVATION      = 'Q10'
+   Q_STAIRCASE          = ''
 
    if ( Proc.Grp == 3 or Proc.Grp == 4)  and  Proc.Prc == 16 then
       Q_FORCE_BLADE         = 'Q01' -- i
@@ -164,7 +165,8 @@ local function AssignQIdent( Proc)
       Q_USE_MILL            = 'Q02' -- i
       Q_USE_ROUGH_TOOL      = 'Q03' -- i
       Q_SIDE_ROUGH_TOOL     = 'Q04' -- i
-      Q_BORE_ON_CORNER      = 'Q06' -- i  
+      Q_BORE_ON_CORNER      = 'Q06' -- i
+      Q_STAIRCASE           = 'Q09' -- i 
    elseif ( Proc.Grp == 3 or Proc.Grp == 4)  and  Proc.Prc == 25 then
       Q_BORE_ON_CORNER      = 'Q01' -- i  
    elseif ( Proc.Grp == 3 or Proc.Grp == 4)  and  Proc.Prc == 30 then
@@ -5665,6 +5667,23 @@ local function TestTwoFacesDownHead( Proc)
    return bDownHead
 end
 
+---------------------------------------------------------------------
+local function MakeStaircaseStep( Proc)
+   -- angolo tra le facce
+   local _, _, _, dAng = EgtSurfTmFacetsContact( Proc.Id, 0, 1, GDB_ID.ROOT)
+   -- se l'angolo tra le facce è maggiore di 90.5 o minore di 80 esco
+   if ( dAng > -80 + 10 * GEO.EPS_ANG_SMALL) or ( dAng < -90.5 - 10 * GEO.EPS_ANG_SMALL) then return false end
+   -- normali delle facce
+   local vtNRiser = EgtSurfTmFacetNormVersor( Proc.Id, 0, GDB_ID.ROOT)
+   local vtNTread = EgtSurfTmFacetNormVersor( Proc.Id, 1, GDB_ID.ROOT)
+   -- identifico quale faccia è l'alzata e quale la pedata
+   local nFaceRiser, nFaceTread = 0, 1
+   if vtNRiser:getZ() > vtNTread:getZ() then
+      nFaceRiser, nFaceTread = 1, 0
+   end
+
+end
+
 ---------------------------------------------------------------------
 -- Applicazione della lavorazione
 ---------------------------------------------------------------------
@@ -5821,6 +5840,10 @@ function ProcessLapJoint.Make( Proc, nPhase, nRawId, nPartId, dOvmHead)
          end
       -- due facce
       elseif Proc.Fct == 2 then
+         -- se V passante e attiva Q per lavorazione speciale scala
+         if Q_STAIRCASE == 1 and Proc.Topology == 'Groove' and Proc.IsThrough == true then
+            return MakeStaircaseStep( Proc)
+         end
          -- se praticamente è lunga come la trave e sono due facce lunghe
          local b3Fac1 = EgtSurfTmGetFacetBBoxGlob( Proc.Id, 0, GDB_BB.STANDARD)
          local b3Fac2 = EgtSurfTmGetFacetBBoxGlob( Proc.Id, 1, GDB_BB.STANDARD)