diff --git a/OpenNest.Core/Geometry/ArcFit.cs b/OpenNest.Core/Geometry/ArcFit.cs
index edf3b7b..758af4d 100644
--- a/OpenNest.Core/Geometry/ArcFit.cs
+++ b/OpenNest.Core/Geometry/ArcFit.cs
@@ -56,6 +56,60 @@ namespace OpenNest.Geometry
             return (new Vector(cx, cy), radius, MaxRadialDeviation(points, cx, cy, radius));
         }
 
+        /// <summary>
+        /// Fits a circular arc constrained to be tangent to the given directions at both
+        /// the first and last points. The center lies at the intersection of the normals
+        /// at P1 and Pn, guaranteeing the arc departs P1 in the start direction and arrives
+        /// at Pn in the end direction. Uses the radius from P1 (exact start tangent);
+        /// deviation includes any endpoint gap at Pn.
+        /// </summary>
+        internal static (Vector center, double radius, double deviation) FitWithDualTangent(
+            List<Vector> points, Vector startTangent, Vector endTangent)
+        {
+            if (points.Count < 3)
+                return (Vector.Invalid, 0, double.MaxValue);
+
+            var p1 = points[0];
+            var pn = points[^1];
+
+            var stLen = System.Math.Sqrt(startTangent.X * startTangent.X + startTangent.Y * startTangent.Y);
+            var etLen = System.Math.Sqrt(endTangent.X * endTangent.X + endTangent.Y * endTangent.Y);
+            if (stLen < 1e-10 || etLen < 1e-10)
+                return (Vector.Invalid, 0, double.MaxValue);
+
+            // Normal to start tangent at P1 (perpendicular)
+            var n1x = -startTangent.Y / stLen;
+            var n1y = startTangent.X / stLen;
+
+            // Normal to end tangent at Pn
+            var n2x = -endTangent.Y / etLen;
+            var n2y = endTangent.X / etLen;
+
+            // Solve: P1 + t1*N1 = Pn + t2*N2
+            var det = n1x * (-n2y) - (-n2x) * n1y;
+            if (System.Math.Abs(det) < 1e-10)
+                return (Vector.Invalid, 0, double.MaxValue);
+
+            var dx = pn.X - p1.X;
+            var dy = pn.Y - p1.Y;
+            var t1 = (dx * (-n2y) - (-n2x) * dy) / det;
+
+            var cx = p1.X + t1 * n1x;
+            var cy = p1.Y + t1 * n1y;
+
+            // Use radius from P1 (guarantees exact start tangent and passes through P1)
+            var r1 = System.Math.Sqrt((cx - p1.X) * (cx - p1.X) + (cy - p1.Y) * (cy - p1.Y));
+            if (r1 < 1e-10)
+                return (Vector.Invalid, 0, double.MaxValue);
+
+            // Measure endpoint gap at Pn
+            var r2 = System.Math.Sqrt((cx - pn.X) * (cx - pn.X) + (cy - pn.Y) * (cy - pn.Y));
+            var endpointDev = System.Math.Abs(r2 - r1);
+
+            var interiorDev = MaxRadialDeviation(points, cx, cy, r1);
+            return (new Vector(cx, cy), r1, System.Math.Max(endpointDev, interiorDev));
+        }
+
         /// <summary>
         /// Computes the maximum radial deviation of interior points from a circle.
         /// </summary>
diff --git a/OpenNest.Tests/GeometrySimplifierTests.cs b/OpenNest.Tests/GeometrySimplifierTests.cs
index 8f891e8..385e2a4 100644
--- a/OpenNest.Tests/GeometrySimplifierTests.cs
+++ b/OpenNest.Tests/GeometrySimplifierTests.cs
@@ -1,4 +1,7 @@
 using OpenNest.Geometry;
+using OpenNest.IO;
+using System.IO;
+using System.Linq;
 using Xunit;
 
 namespace OpenNest.Tests;
@@ -127,4 +130,52 @@ public class GeometrySimplifierTests
         // Index 6 is the fitted arc replacing the second run
         Assert.IsType<Arc>(result.Entities[6]);
     }
+
+    [Fact]
+    public void Apply_DynaPanDxf_NoGapsAfterSimplification()
+    {
+        var path = @"C:\Users\aisaacs\Desktop\Sullys Q29 DXFs\SULLYS-031 Dyna Pan.dxf";
+        if (!File.Exists(path))
+            return; // skip if file not available
+
+        var importer = new DxfImporter();
+        var result = importer.Import(path);
+        var shapes = ShapeBuilder.GetShapes(result.Entities);
+
+        var simplifier = new GeometrySimplifier { Tolerance = 0.004 };
+
+        foreach (var shape in shapes)
+        {
+            var candidates = simplifier.Analyze(shape);
+            if (candidates.Count == 0) continue;
+
+            var simplified = simplifier.Apply(shape, candidates);
+
+            // Check for gaps between consecutive entities
+            for (var i = 0; i < simplified.Entities.Count - 1; i++)
+            {
+                var current = simplified.Entities[i];
+                var next = simplified.Entities[i + 1];
+
+                var currentEnd = current switch
+                {
+                    Line l => l.EndPoint,
+                    Arc a => a.EndPoint(),
+                    _ => Vector.Invalid
+                };
+                var nextStart = next switch
+                {
+                    Line l => l.StartPoint,
+                    Arc a => a.StartPoint(),
+                    _ => Vector.Invalid
+                };
+
+                if (!currentEnd.IsValid() || !nextStart.IsValid()) continue;
+
+                var gap = currentEnd.DistanceTo(nextStart);
+                Assert.True(gap < 0.005,
+                    $"Gap of {gap:F4} between entities {i} ({current.GetType().Name}) and {i + 1} ({next.GetType().Name})");
+            }
+        }
+    }
 }
diff --git a/OpenNest/Forms/CadConverterForm.cs b/OpenNest/Forms/CadConverterForm.cs
index 112212b..c104896 100644
--- a/OpenNest/Forms/CadConverterForm.cs
+++ b/OpenNest/Forms/CadConverterForm.cs
@@ -494,13 +494,30 @@ namespace OpenNest.Forms
 
             using var dlg = new SaveFileDialog
             {
-                Filter = "DXF Files|*.dxf",
+                Filter = "DXF 2018 (*.dxf)|*.dxf|" +
+                         "DXF 2013 (*.dxf)|*.dxf|" +
+                         "DXF 2010 (*.dxf)|*.dxf|" +
+                         "DXF 2007 (*.dxf)|*.dxf|" +
+                         "DXF 2004 (*.dxf)|*.dxf|" +
+                         "DXF 2000 (*.dxf)|*.dxf|" +
+                         "DXF R14 (*.dxf)|*.dxf",
                 FileName = Path.ChangeExtension(item.Name, ".dxf"),
             };
 
             if (dlg.ShowDialog() != DialogResult.OK) return;
 
-            var doc = new ACadSharp.CadDocument();
+            var version = dlg.FilterIndex switch
+            {
+                2 => ACadSharp.ACadVersion.AC1027,
+                3 => ACadSharp.ACadVersion.AC1024,
+                4 => ACadSharp.ACadVersion.AC1021,
+                5 => ACadSharp.ACadVersion.AC1018,
+                6 => ACadSharp.ACadVersion.AC1015,
+                7 => ACadSharp.ACadVersion.AC1014,
+                _ => ACadSharp.ACadVersion.AC1032,
+            };
+
+            var doc = new ACadSharp.CadDocument(version);
             foreach (var entity in item.Entities)
             {
                 switch (entity)