The last instalment and the final details: checks and gaps. Check rails are the smallest part and the most important; stopping the wheelset sliding down the wrong road by holding them over to the stock rail as they approach the nose. Nothing but a short length of rail cranked slightly at each end. The length is determined as below: the LH end slightly beyond or level with the wing rail on the crossing, the RH end beyond or level with the gap in the rails. Here my generous Triang friendly clearances means they are set at about 1.5mm in, finescalers would want to be 1mm or less. P4 is about half a mill or something, but then if that's your thing, then you won't bother with all this rubbish. Solder your CLEAN rail to the CLEAN sleepers. Gaps are a bit personal. I mentioned Laurie Maunder in part one. Laurie's system is to gap down between the blade and the stock rail thus connecting the stock rail to the middle and changing its polarity to either side. I tend now to use the EM Gauge society gapping suggestion with a couple of mod's: From the right gap down the middle to the arrow where the rails should be cut. with a disc or saw. Beyond the arrow gap down the middle of each road. This means the 'frog' to the right of the arrow is dead and needs a switch to change the polarity, but the blade is live to its own side all the time.