=== modified file '3d-viewer/3d_draw.cpp'
--- 3d-viewer/3d_draw.cpp	2013-10-04 08:42:09 +0000
+++ 3d-viewer/3d_draw.cpp	2013-10-05 19:12:36 +0000
@@ -460,9 +460,14 @@
     {
         int copper_thickness = g_Parm_3D_Visu.GetLayerObjectThicknessBIU( LAYER_N_BACK );
         int zpos = g_Parm_3D_Visu.GetLayerZcoordBIU( LAYER_N_BACK );
-        int thickness = g_Parm_3D_Visu.GetLayerZcoordBIU( LAYER_N_FRONT )
-                        - g_Parm_3D_Visu.GetLayerZcoordBIU( LAYER_N_BACK );
-        zpos += (thickness/2) + (copper_thickness/2);
+
+		// reduce substrate thickness by 1% to avoid graphics error 
+        int thickness = (g_Parm_3D_Visu.GetLayerZcoordBIU( LAYER_N_FRONT )
+                        - g_Parm_3D_Visu.GetLayerZcoordBIU( LAYER_N_BACK )) * 0.99;
+
+		// place the substrate right in the middle between FRONT and BACK layer
+        zpos += (thickness/2) + (thickness/0.99*.01/2);
+
         thickness -= copper_thickness;
         EDA_COLOR_T color = g_ColorsSettings.GetLayerColor( EDGE_N );
         SetGLColor( color, 0.8 );