diff --git a/EgtMachKernel.rc b/EgtMachKernel.rc
index 4165e71..3c8b343 100644
Binary files a/EgtMachKernel.rc and b/EgtMachKernel.rc differ
diff --git a/Operation.cpp b/Operation.cpp
index 177edff..3b2c772 100644
--- a/Operation.cpp
+++ b/Operation.cpp
@@ -1065,8 +1065,9 @@ Operation::ApproxWithArcsIfUseful( ICurveComposite* pCompo, bool bCareTempProp)
   // limito l'approssimazione alle curve piane
    Frame3d frRef ;
    frRef.Set( ORIG, vtExtr) ;
+   Frame3d frInvRef = frRef ; frInvRef.Invert() ;
    BBox3d b3Crv ;
-   if ( ! pCompo->GetBBox( frRef, b3Crv)  ||  abs( b3Crv.GetMax().z - b3Crv.GetMin().z - dThick) > 100 * EPS_SMALL)
+   if ( ! pCompo->GetBBox( frInvRef, b3Crv)  ||  abs( b3Crv.GetMax().z - b3Crv.GetMin().z - dThick) > 100 * EPS_SMALL)
       return true ;
   // porto la curva nel suo piano perchè ApproxWithArcsEx funziona bene solo nel piano XY (all'uscita va ripristinato il rif. originale)
    pCompo->ToLoc( frRef) ;