Friday 2 January 2015

Welcome to Signals Branch

Welcome to Signals Branch, a blog that I will be using to support my release of a number of NSWGR signal 'kits' and other items through an online shop at Shapeways, an on demand 3D printing company located in both Eindhoven, The Netherlands and also New York, USA. Australian print orders have recently been allocated to the New York facility.

Please note that the prices on the Shapeways site are in US$ not Australian so there will be a conversion to AU$ based on when your order is placed.

The signal posts have been designed to be printed in the Shapeways White Strong and Flexible material (WSF).

The White Strong and Flexible material is a laser sintered nylon which has a low print resolution but is quite strong and flexible. The flexibility is of advantage for a signal on a layout as it will actually bend a bit if knocked or if it is caught by clothing when someone reaches over the layout.

One disadvantage of 3D printing is that for each material there are minimum tolerances for printing, such as minimum wall thickness, minimum supported wire (rods or other small cross sections), minimum unsupported wires, minimum detail size, etc. As a result the finer details sometimes have to be enlarged to be printable and for that matter, even to be seen.

By choosing to use the White Strong and Flexible material the ladder and railings are thicker than would be found in an etched signal kit. If wire railings are preferred then the printed ones may be cut off and wire ones substituted in fine holes that will need to be drilled at the previous signal attachment points. Similarly, the existing ladders could be cut away and etched ladders may also be added. Be aware though that the nylon is tough and doesn’t cut easily even with a sharp hobby knife. A pair of new transistor snips could be used where there is access. Transistor snips are ground flat on one side of the cutting edges so they can be pressed against a surface to give a reasonably smooth flat cut.

The upside of the printing process is that other parts may be of a more correct thickness and have detail such as the cast iron support under the beams of a bracket signal. In an etched signal this support is usually just a thin brass shape. You will also find that there are individual boards on the platforms with gaps that can be seen through.

The White Strong and Flexible material is nylon which doesn’t normally glue or take paint well, in this case however, due to the laser sintered fine particles there is a very good key for both glue and paint. The preferred glue is Super Glue (ACC – cyanoacrylate) and acrylic water based paints also work well, enamels can be used as well but the acrylics are usually a bit thicker which can assist in sealing and smoothing the surface of the White Strong and Flexible material.

The signal arms and other detail parts of the signals are printed in the Shapeways Frosted Ultra Detail material (FUD). The Frosted Ultra Detail material is an acrylic resin which is printed by using a ultra-violet light to set the resin layer by layer. This material will give a high print resolution but is hard and somewhat brittle in thin sections, a disadvantage when knocked. It is also much higher priced which can restrict its use for larger items.

Well, I hope you find something of value among the things I have designed, enjoy.


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