diff --git a/Drilling.cpp b/Drilling.cpp
index c31df87..5bae156 100644
--- a/Drilling.cpp
+++ b/Drilling.cpp
@@ -1219,11 +1219,20 @@ Drilling::GetHoleData( SelData Id, Hole& hole)
    const ICurveArc* pArc = GetCurveArc( m_pGeomDB->GetGeoObj( Id.nId)) ;
    if ( pArc == nullptr) {
       const ICurveComposite* pCompo = GetCurveComposite( m_pGeomDB->GetGeoObj( Id.nId)) ;
-      if ( pCompo == nullptr)
+      Point3d ptCen ;
+      Vector3d vtN ;
+      double dRad ;
+      bool bCCW ;
+      if ( pCompo == nullptr  ||  ! pCompo->IsACircle( 100 * EPS_SMALL, ptCen, vtN, dRad, bCCW))
          return false ;
-      const ICurveArc* pArcTmp = GetCurveArc( pCompo->GetFirstCurve()) ;
-      if ( pArcTmp == nullptr  ||  ! pMyArc.Set( pArcTmp->Clone()))
+      pMyArc.Set( CreateCurveArc()) ;
+      if ( IsNull( pMyArc)  ||  ! pMyArc->Set( ptCen, vtN, dRad))
          return false ;
+      //if ( pCompo == nullptr)
+      //   return false ;
+      //const ICurveArc* pArcTmp = GetCurveArc( pCompo->GetFirstCurve()) ;
+      //if ( pArcTmp == nullptr  ||  ! pMyArc.Set( pArcTmp->Clone()))
+      //   return false ;
       Vector3d vtExtr ; pCompo->GetExtrusion( vtExtr) ;
       pMyArc->SetExtrusion( vtExtr) ;
       double dThick = 0 ; pCompo->GetThickness( dThick) ;
diff --git a/Operation.cpp b/Operation.cpp
index f2ba688..b0c0b11 100644
--- a/Operation.cpp
+++ b/Operation.cpp
@@ -1952,7 +1952,7 @@ Operation::TestCollisionAvoid( const DBLVECTOR& vAxStart, const DBLVECTOR& vAxEn
       pMch->LinkFixtureToGroup( nFxtId, sTable) ;
   // distanza di sicurezza
    double dSafeDist = m_pMchMgr->GetCurrMachiningsMgr()->GetSafeZ() ;
-   dSafeDist = max( 0.9 * dSafeDist, dSafeDist - 10.0) ;
+   dSafeDist = min( dSafeDist, max( 0.5 * dSafeDist, 10.0)) ;
   // Vado nelle posizioni da controllare
    const int COLL_STEP = 16 ;
    bool bCollide = false ;
diff --git a/Pocketing.cpp b/Pocketing.cpp
index 012ead6..d1e00ff 100644
--- a/Pocketing.cpp
+++ b/Pocketing.cpp
@@ -2565,7 +2565,7 @@ Pocketing::CalcSpiral( const ICurveComposite* pCompo, bool bSplitArcs,
 
   // se circonferenza, chiamo la funzione specializzata
    Point3d ptCen ; Vector3d vtN ; double dRad ; bool bCCW ;
-   if ( pCompo->IsACircle( 10 * EPS_SMALL, ptCen, vtN, dRad, bCCW)) {
+   if ( pCompo->IsACircle( 100 * EPS_SMALL, ptCen, vtN, dRad, bCCW)) {
       double dIntRad = 0 ;
       if ( m_Params.m_nSubType == POCKET_SUB_SPIRALOUT  &&  GetLeadInType() == POCKET_LI_HELIX) {
          dIntRad = min( 0.5 * min( m_Params.m_dLiTang, m_TParams.m_dDiam), dRad - dOffs) ;