Monday, December 29, 2014

3D Printed NSWGR Lower Quadrant Signals

In my last post I mentioned that I will be releasing a number of NSWGR signal 'kits' 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.

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, a disadvantage when knocked.

The Signal Posts

I have uploaded 3D models for the following signals:

16' post - 1 Signal arm.
18' post - 1 Signal arm
18' post - 2 Signal arms
23' post - 1 Signal arm
23' post - 2 Signal arms
23' post - 3 Signal arms
27' post - 1 Signal arm
27' post - 2 Signal arms
27' post - 3 Signal arms
27' post - 1 Signal arm + Lamp above (Distant Signal)
27' post Bracket Signal - Right Hand lower Signal arm
27' post Bracket Signal - Left Hand lower Signal arm
27' post Bracket Signal - Right Hand - Even height Signal arms
27' post Bracket Signal - Left Hand - Even height Signal arms
Centre post Bracket Signal - Right Hand lower Signal arm
Centre post Bracket Signal - Left Hand lower Signal arm
Centre post Bracket Signal - Even height Signal arms
Offset Bracket - Right Hand 1 Signal arm
Inverted Bracket - Right Hand 1 Signal arm
27' post Triple Bracket - Centre post highest - Left and Right lower at same height.

Some example renders of signals:

Close up of detail on bracket signal

Coloured left hand bracket

27' post with 3 signal arm positions

Centre post bracket with even height dolly posts

Right hand offset bracket

Triple bracket
 
Inverted bracket
To overcome some problems printing the ladders I have had to add some ladder supports which will need to be removed with transistor nippers as shown in the following image.

The 'Y' shaped ladder supports are to be removed.
Detail Parts
 
To complement the above signal selection I have designed and uploaded a number of signal arm and detail part 'sprues'.

I have tried to cover various combinations of signal arms with these 'sprues'.

The following signal arms will be available in various combinations:

39 1/4" arms - Main line
36" arms - Main line
30" arms - Passing and crossing loops
Siding arms
Shunt Ahead arms
Wrong Road arms


Standard Bracket set

Distant set

Siding and Shunt Ahead set

39" and 36" arms set

Inverted Bracket set
Centre post Bracket set
Spares set
Siding and Wrong Road
Some of the above are also available as double sets.
 
The above detail sets will come with a frame around them to hopefully stop any parts breaking off the sprue during cleaning and handling post-printing. If a part does break off the sprue it usually means that the print is rejected as the person handling the item doesn't know that the part has just broken away from a sprue, they think that the item is broken. Shapeways will re-print the item at their cost in this case which can delay the delivery. Unfortunately, if the item keeps breaking they will reject the item and withdraw it from sale. At this point I will be notified to correct the design. Hopefully the frames will stop this from happening.
 
2 x 30" Arms and 2 x Siding Arms set in frame
Extra Items
 
I have also designed a few items that might be of assistance to the modeller:
 
Operating mechanism for use with other signals such as made by Uneek

Type 1 SG90 servo mounting (for servos as used by Tam Valley) - Can be used for points

Type 2 SG90 servo mounting (for servos as used by Tam Valley)

Type 3 SG90 servo mounting (servos as used by Tam Valley) with 'wire in tube' mounting

'Wire in tube' bracket designed to be screwed to any signal operating mechanism
 
Fascia mounting for Tam Valley Singlet control board in white, green or black
Well, that's about the range so far and I am still hoping to open a Shapeways shop in early January.
 
I have been asked about upper quadrant and the tubular lower quadrant signals and I haven't made any decision about those as yet as there are some very different challenges with the tubular posts but who knows.
 
 

3 comments:

Lance said...

Fabulous Ray!
Looks like a great variety of MUCH needed models. I guess I'll start setting $ aside. I'm sure you'll let us know when / where we will be able to order

Lance

Ray P said...

Thanks Lance.

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