... down below the top of the stock rail to fit under the head of the stock rail (undercut). This is in order to have sufficient strength at the tip. Such a blade acts only as a guide to the wheel flanges for the first part of its length and does not actually support the weight of wheels running onto it until they have reached some way along it. Undercut switches can often be identified in photographs because the shiny top of the open blade stops some way short of the tip. joggle-3.gif 2_152258_310000000.png 2_152258_310000001.png Here are some photos of an undercut switch. You can see from the shiny marks on the top of the blade that it starts to take some part of the wheel load at about the position of the second stretcher bar. Up until that point it is simply guiding the wheel flange, and is dull on top: 2_171152_120000001.jpg 2_171152_120000000.jpg You can see that the tip is very thin, and if continued up to the top of the stock rail it would be a knife edge. The way to model this is to ...