... the mm DXF in inches. Consequently the saved STL is 25.4 times too big, and it's not surprising Slice3r finds it easy to slice. However, if I export the DXF in inches, which seems to be the only option TurboCAD is happy with, the resulting saved STL file is actual model size. Slice3r then reports "no layers found" in the STL. Clearly I need to change some settings in Slic3r. Over to Andy. Here attached is a current 3D DXF file, and the STL to follow: 2_050855_460000000.png You might like to try them in your CAD program. cheers, Martin. Attachment: attach_2723_2734_test_3d_printing _18_08_05_1326_41_mm.dxf 226 posted: 5 Aug 2018 14:06 from: Martin Wynne And here's the STL. Note that if you open the STL in TurboCAD, the rectangles from the DXF have all been split along a diagonal into triangles. I find that makes the wireframe view very confusing. I think this STL is actually 25.4 times too big. It started life in EM gauge (4mm/ft). Martin. Attachment: ...