Page 7 - March April 2000

􏰁􏰁
Point switches
􏰀 Kadee 308 operating cord
Well the following are mine and the accompanying design (Fig. 1) is based on them...
1. Choose appropriate materials for the purpose.
2. Put material where it contributes and remove it where it doesn’t. (All modern bridges use hollow sections for this reason). For example a 20mm X 8mm rib underneath a 2 in. wide track bed in 4mm ply reduced its deflection under load by a factor of 70; this arrangement is 2.5 times better than the same track bed in 12mm chipboard. Also it is much better at holding its shape against time and damp. The positions of the ribs needs to be chosen to suit the track plan and to avoid point motors/drives and uncouplers.
3. Glue and screw (or at least glue and pin) all joints (usually 3/4in. X No 6 screws)
4. Select any timber for straightness and freedom from knots, particularly important for small sections. (You might get some funny looks but it is OK if you do it discreetly and don’t block the aisles in the DIY store or poke other customers in the eye.)
5. Try to ensure that all exposed surfaces are coated with some form of sealer (paint, varnish etc.) to minimise moisture entering the material and causing distortion.
Clamps holding reinforcing rib for glueing
􏰂
APRIL 2000 7
Photo 1 (above)
Access for point switches, etc.
Photo 2 (left)
Boards under construction