Could someone please tell me exactly what the point rail gap is and how to measure it as to meeting specs? Thanks, Jim
The space between the point rail and the stock rail (for the point which isn't going to rode on)? An NMRA gauge is the best tool for that.
between the stock rail and the points. This gap prevents a short between the wheel and the points, or a derailment due to hitting the points when the turnout is not aligned for the route.
At the throwbar, the points the moving rails, the stock rails are the two outer fixed rails. Depending on the position of the switch, one point will be against its stock rail, the other will be away from its. The gap is the open space between that point and stock rail (I.e. the space where the wheel goes when following the stock rail)
It’s the width of an S Scale 2x4, the standard wood tie used in hand laying track ( it matches the PC tie thickness). We place one of these ties in the gap while soldering, as it keeps the solder out of the gap while also holding the point at the correct angle.
A picture surely is worth a thousand words. Thanks for sending. I have one more question: Then if the gauge fits within this gap the gap is correct, but does it matter if the gap is slightly larger than the gauge points?
http://mrr.trains.com/videos/expert-tips/2011/09/video-how-to-use-an-nmra-gauge https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-3.2_2010.05.08.pdf
If your points are hinged, a bit extra shouldn't be a problem, but if you are just bending the rail, as in a handlaid turnout, you shouldn't let it get too much bigger. Just don't let it get huge. The wider the gar the harder to actuate.
At the point rails it wouldn't hurt if they were a little wide other than travel and flex as has been pointed out. The clearance at the guard rails, on the other hand, is actually important. NMRA has specs for each scale.
Gap is part of the problem, but you can still mess up a point if the approach angle is wrong. This is why we use wood ties, it sets the gap AND the approach angle when soldering.