... edge at the top of the tip, with the running edge dead straight all through the filing aid. The filed length is the same as for the back of the blade, running out to nothing at 2. Some more ink on the rail may help to see it. Finally fettle it with abrasive paper to make a smooth top edge against the stock rail for the wheel flanges. This will cause the knife edge at the end to be reduced a little below the top of the stock rail in the prototype manner. 2_010613_550000000.png That makes a left-hand point blade. Now print a right-hand version and repeat the whole process to make a right-hand blade. For "A" blades make the template a 9ft straight switch and 1:24 crossing angle. The planing length is 22mm. If you are careful these filing aids should be good for several blades. But cost next to nothing if you need to replace them. More about planing lengths and the stock gauge here: http://templot.com/companion/real_track.php ...