This is a wooden grade crossing designed for O gauge tubular track. The design consists of two OpenSCAD programs, one makes a crossing for straight track and the other makes a crossing for O-31, O-42, O-54 and O-72 curved track. OpenSCAD generates an STL file which can be sliced for your 3D Printer.
The top of each piece represents wooden boards that are bolted together to make the crossing. Each crossing consists of four pieces. The two center pieces go along side of
the center rail and the other two go on the outside of the outer rails. The curved crossing pieces are accurately curved to match the actual track. If you look in the OpenSCAD program, you can see what values I used for the diameters of the four different curves supported. I used the RR-Track program to measure the center rail to center rail diameter of a loop. This seemed to work pretty well as the finished curved crossing pieces can be glued directly to the center rail and to the outer rails.
Each piece of the crossing has a diagonal side to clear the ties and the center rail insulator.
The difficult dimension in this project was the 'space' left on the inside edges of the outer rails for the wheel flanges. I measured a bunch of track and there is about 0.55 inches between the inside edges of the rails. I ended up making the gap about 0.15 inches - which made the crossing pieces 0.4 inches wide. This seems to work on my layout with my mostly MTH rolling stock. You might need to make this dimension smaller to have a larger flange gap.
The grade crossing pieces should fall about 0.07 inches below the tops of the tubular rail.
In the OpenSCAD program, you select the length of the crossing. I found that 4.5 inches works well for rural (1 lane) roads and 6.0 inches works for town (2 lane) roads.
Even with the diagonal side, you should be able to print this without using support.
With this grade crossing, you end up with a grade that is many feet above the road painted on the plywood layout. You will have build up the road grade and start to get a more realistic layout.
Full details and the OpenSCAD program available on Thingiverse :
