Sitting looking at a sunny but smoggy Beijing morning, here are a few ideas on PECO track.
The PECO range of points offer a consistent geometry and make track planning and laying all too easy. However, one track configuration caused problems on my second board. The diamond crossing that carries a siding and the main short line is fed by two points, as the picture below shows.
The PECO fine scale code-55 range has a lovely short crossing, that would fit between two large or medium radius code-55 points, all fitting perfectly. At least, until one wires it up (oh no, not more wiring problems). The crossing is live frog, and the frog polarities need to be changed according to the leg that is carrying the train.
Now, the code-55 crossing is ready wired, with four connections for the four crossing frogs. As I thought about it, I realised that although a live frog crossing can be linked to the point frog polarity for, say, a double junction, the polarity of the crossing will depend on the setting of the two points, and cannot be unique. To use live frogs, one needs to have an additional switch for the crossing (or go DCC, which I’m not.)
Of course, there would be no problem with a dead frog crossing. And PECO make a code-80 universal short crossing. Using the heavier rail is not a problem – if anyone notices it, remind them that prototype crossings often had heavier rail than the track on either side, due to the heavy wear at a diamond. But just to annoy us, the geometry and angles of the universal range is slightly different from the code-55 fine scale range. So although code-80 joins well with code-55 with a normal fishplate, perhaps with a tiny bit of tidying with a file, the geometry doesn’t work.
Not to be denied, I got out all my points and tried to get the geometry to work. I soon came up with the lash up shown below. The code-55 small radius point has a larger frog angle than medium and large radius points. If I used a short Y point on the other leg of the diamond, the angles were spot on through the junctions.
There was one catch, of course. The large radius / short Y point combination gave a track spacing of about 40mm. This was easily reduced to 27mm or so (the PECO standard spacing) by taking one sleeper and about 10mm of track off the two points and the crossing. Take care doing this – take too much off and the short frog rail will probably have inadequate support and drop out (as my first crossing did – fortunately I had a second one in the rail box.)
The end result is not only one with the correct geometry, it will also look interesting on the layout – breaking away from the standard PECO geometry. Now to lay it and wire it up.