3D-Printed Sn3½ Flexible Track

As an experiment, I recently tried 3D printing some sleepers for correct-scale Sn3½ track, using a similar principle to commercial flexible track.  I used the Makerbot Replicator printer which we currently have at home on loan, using a chocolate brown filament so the basic colour is about right.

It seems to work fairly well, although it would be a bit time-consuming printing sleepers for a basement-size layout.  For a modest layout, though, it appears to be a feasible proposition.  

The photos show the track with Code 70 rail (weathered, from MicroEngineering) but code 83 would fit too as the dimensions of the base of the rail are the same.  The tops of the sleepers have a textured finished from the printing process rather than the fake woodgrain on commercial track.

3D printed track with handlaid track in the background.
Note: I don't recommend use of unsupported MDF as trackbed
as it will inevitably sag - this is just a temporary arrangement.

The longest length which will fit in the printer is 18 sleepers @ 12 mm spacing which equates to 216 mm of track, so about 4 lengths would be required for a yard of track.  Printing each length takes just under one hour.  It may well be possible to print several lengths at one time side-by-side which wouldn't save much time but would save on trips back and forth to the printer.

Computer rendering of the sleepers.

As for cost, the cost of the plastic material works out to about $6 per yard, plus the cost of the rail of course (not including any costs for the 3D printer itself).  As a comparison, the NorthEastern scale lumber which I have used in the past for handlaid track costs about the same.

I also 3D-printed a jig to make it easier to insert the rail by keeping the sleepers parallel to each other so the rail slides in relatively easily.  So far, I have made about 1.5 metres of track.  

The 3D design could be changed to print straight track or fixed curves of any desired radius rather than having "flexible" track.  For example, if laying parallel tracks in a yard it could be easier to lay lengths of straight track to avoid the inevitable "wobbles" with flexible track.

WAGR Rail Heights in S Scale

Rail size Weight (lbs) Per Yard	Height in Inches (HT)	Height in Millimeters (HT)	S Scale in Thou’s (HT)	Nearest Code Equivalent	Manufacturers (I’m Sure There’s Plenty More)
45	3 11/16	94	.057	55	Micro-Engineering
58	4 7/16	113	.069	70	Micro-Engineering
63	4 5/8	117	.072	70 OR 75	Micro-Engineering Peco
82	5 3/8	136	.084	83	Micro-Engineering Peco

The 82 lbs data sourced from The S Scale Model Railway Society at www.s-scale.org.uk/rails.htm

During a recent visit to the Railway Museum at Bassendean, one of the tasks that I set myself was to find and measure the height of various weights of rails on site so I could find their equivalents in S Scale when I returned home.

Why.? Because when fellow modellers would discuss codes in rail sizes, I had no idea of what they were talking about, so it was an exercise in understanding what rail to codes was all about.

I am not claiming that the above table is 100% accurate as wear has an impact on the height but I did try and find several examples of each weight of rail to get the best readings.

 

The modeller will need to research the station or line in which it is to be modelled to determine rail codes to use, the State Records Office and Rail Heritage WA have large collections of track diagrams which clearly show the weight of rails used within station yard layouts.

The S Scale Model Railway Society on the UK also has a comprehensive list of prototype rail data on its web site at www.s-scale.org.uk/rails.htm together with conversions to S scale.

Thanks to Richard Stallard in giving guidance in this piece. Richard had previously wrote an article in ASNM regarding the same subject but in greater detail (unknown to me when I started my research).

RC