diff --git a/LuaLibs/WProcessLapJoint.lua b/LuaLibs/WProcessLapJoint.lua
index 3ce03ef..0d4d3cc 100644
--- a/LuaLibs/WProcessLapJoint.lua
+++ b/LuaLibs/WProcessLapJoint.lua
@@ -1,4 +1,4 @@
--- WProcessLapJoint.lua by Egaltech s.r.l. 2021/04/20
+-- WProcessLapJoint.lua by Egaltech s.r.l. 2021/04/22
 -- Gestione calcolo mezzo-legno per Pareti
 
 -- Tabella per definizione modulo
@@ -1130,10 +1130,11 @@ local function MakeByMill( Proc, nFacet, nOthFac, nRawId, b3Raw, dSideDist)
    -- aggiungo geometria
    EgtSetMachiningGeometry( {{ Proc.Id, nFacet}})
    -- sistemo i parametri di attacco e uscita
-   EgtSetMachiningParam( MCH_MP.STARTADDLEN, -dMillDiam/2 + WD.MID_GAP - WD.MID_SIC)
+   local dAddLen = ( WD.MID_GAP or 50) - ( WD.MID_SIC or 5)
+   EgtSetMachiningParam( MCH_MP.STARTADDLEN, -dMillDiam/2 + dAddLen)
    EgtSetMachiningParam( MCH_MP.LITANG, 0)
    EgtSetMachiningParam( MCH_MP.LIPERP, dSideDist + WD.CUT_SIC)
-   EgtSetMachiningParam( MCH_MP.ENDADDLEN, -dMillDiam/2 + WD.MID_GAP - WD.MID_SIC)
+   EgtSetMachiningParam( MCH_MP.ENDADDLEN, -dMillDiam/2 + dAddLen)
    EgtSetMachiningParam( MCH_MP.LOTANG, 0)
    EgtSetMachiningParam( MCH_MP.LOPERP, dSideDist + WD.CUT_SIC)
    -- imposto posizione braccio porta testa