Ace posted:A loop-to-loop O27 layout can fit on a 30" x 79" door and has much more interesting action than a plain oval. Non-derailing switches provide an automatic "random-route" feature, so the train runs through the central junction in different directions.
I currently have a temporary layout set up with this plan. I use standard-O switches (#O22 switches with O31 curves) which have a superior non-derailing function. Non-derailing O27 switches might overheat with the train going over them so frequently.
Standard-O track is easily connected to O27 track simply by forcing standard track pins into the O27 rails. It may help to spread the rail web slightly with a screwdriver before inserting the larger pins. The O27 track needs some shimming to get up to the height of the switches. The O27 curves allow this plan to fit on a standard-size 30" x 79" door.
conventional tubular track
The track overhangs the table ends slightly; you could tack 1x2 strips on the ends to extend the table. Some track is cut to fit. The 5.8" straight sections relieve the S-curves and require only a little extra length in the plan. Add spurs and more track if you like.
I built a layout in o27 using more or less this schematic for my office. The difference was that the return loops were separated and placed at opposite corners of my office cube atop the walls. They were connected by two tangents of track and a 90 degree curve at the corner of the cube.
Using the non derailing feature of the switches, the train went the opposite direction through each loop each time.
