GW Auto Trailers ..... almost more varieties than Heinz!

[John Candy]

GWR Auto Trailers

Preamble/Overview.

When it comes to push-pull trains, the GWR was a pioneer and possibly operated more than any other railway.
The majority of branchlines (and many mainline stopping services) were operated in this fashion and a vast number of driving /auto trailers were constructed.

So, you have a 48XX (later 14XX) 0-4-2T, either electric (most likely from a GRS kit) or live steam from Kingscale, but no autotrailer to haul/propel.

At one time GRS did offer a kit for an auto trailer (based on diagram A10) but it is many years since that was deleted from their range. Occasionally, a ready-built example may pop up in an auction catalogue but usually in poor condition (these kits did not age well, a weakness of the design, using thin resin castings which warped). If you do come across one of these, they are not beyond rescue but it will require confidence and drastic action : The result of a well-executed rebuild is an impressive vehicle.

Failing a "rescue" project, your only option is to scratchbuild.

This is to be a guide to building a GWR auto trailer. The fact they were built over a very long period, from the turn of the 20th century until the early 1950s (and many were converted from even older Steam Railmotors) resulted in a multitude of carriage diagrams with varying configurations .
There were, however, groups of diagrams which shared common parts, so a "family" likeness was a thread running through the designs.
When it comes to modelling these trailers, advantage can be taken of this by producing modules suited to multiple diagrams.

The particularly"fiddly bits" are the inset doorways, toplight windows and the angled ends but these suit themselves to modular construction, since they are common to a range of diagrams.

For my first project I have selected diagrams "Q" and "U" but several of the 3D printed modules suit a wider range of diagrams. These two chosen diagrams are both 70ft trailers with gangway connectors at one end (only a few diagrams included gangways to the adjacent coach to enable the guard to issue tickets to passengers boarding at unstaffed halts).

Diagram "Q" has no luggage compartment and entrance doors at each end only , whereas "U" has a luggage compartment, a central passenger entrance and a driver's compartment.  "Q" was originally designed as an intermediate trailer (no driving compartment) but were later fitted with control apparatus at one end, while"U" was built as a driving trailer.

The first stage of the project is to 3D print all those components which are best-suited to that method of production. A large amount of time will be involved in the printing process and I will split the process into stages. The files to produce the subjects are provided as STL files.

Part One : To Begin .... The Windows.

There were two basic patterns of window used with wooden panelled autotrailers : The original type had a main glazed light enclosed in a bolection moulding, with separate toplights above (as seen in the A10 diagram which was the basis of the GRS kit). The final version (used in diagrams "Q","R","T" and "U" only) were of a design where the toplight was part of a unitary window unit enclosed within the overall bolection moulding, giving a more modern appearance.

I have chosen to model diagrams "Q" and "U" to take advantage of this simplified construction as it will enable each 3D printed unit to be inserted into a single cutout in the carriage side.



I am providing three widths of window module to suit diagram "U", two of which also suit diagram "Q". 
gauge3.info/downloads/largewindow.stl
gauge3.info/downloads/mediumwindow.stl
gauge3.info/downloads/smallwindow.stl
The requirements are:
Diagram "Q" .... 14 x medium plus 16 x small
Diagram "U" .... 10 x large plus 8 x medium plus 8 x small

Books Recommended : Great Western Auto Trailers Part One (John Lewis / Wild Swan) and Great Western Coaches Part 2 (Jim Russell / OPC)

COMING NEXT : Door/entrance Modules.

[Nick]

John,

Excellent. So glad you are doing this. Let's hope it will encourage others to start scratch building in G3, in the same way as Mike's small tank engine project when that gets going. I'll be following this series with interest.

Nick

[LankyTank]

A 'coach' that is on my to-do list - one day, so will be following this with great interest.

Thanks
Barry

[John Candy]

Part 2 : The Door Modules

These two modules are standard parts, suiting many diagrams other than those being described here.
The  central passenger/wider doorway module is also used at the ends of some diagrams but for the purposes of this project, it is used at both ends of diagram "Q" and forms the central entrance of diagram "U".
The narrower (driver's) doorway is here being used for diagram "U".
The "wings" attached to the modules are to locate the main side components and are to be trimmed to suit the application/orientation.

   

gauge3.info/downloads/passgrdoor.stl
gauge3.info/downloads/driverdoor.stl
Diagram "Q" requires 4 x passgrdoor.stl
Diagram "U" requires 2 x passgrdoor.stl plus 2 x driverdoor.stl

NEXT UP : The Headstocks

(General Note : The parts are being presented here in no particular sequence .... there is a queue for the printer time and parts are sequenced to suit availability and only listed here when a part has been prepared to be photographed. The material being used is black PLA and it is impossible to successfully photograph before priming in a photo-friendly colour).

[IanT]

Very interesting 'hybrid' approach to scratch carriage building John, combining traditional modelling methods with printed detail parts if I understand correctly. Makes a lot of sense to 'nervous' printers (e.g. myself) who aren't so keen on extremely large prints that take forever to actually print.

Thank you for sharing...

Regards,

IanT 

[John Candy]

Thank you for the expressions of support for my efforts.

The idea is, as Ian has said, to combine a variety of techniques and materials.

The most intricate parts are being 3D printed whilst others are to be laser cut and die-cut from timber, card  and sheet plastic.
The four machines at my disposal are the Snapmaker 2 A350 (3D FDM printer/low power laser cutter/ CNC mill combo), Elegoo Mars2 Pro (3D resin printer), Cricut "Maker" (die-cutter for card/paper/plastic sheet) and (newly arrived) the XTool M1 (a combined laser cutter and die-cutter).

Traditional modelling methods will be confined to the use of metal for some of the load-bearing components.

The files provided will cover 3D print/laser cutting/die-cutting as appropriate. The manual aspects will be covered in the construction notes.

Regards,
John.

[John Candy]

Part 3 : The Headstocks

This module applies to all diagrams of the conventional type auto trailers with open internal layout  EXCEPT A6 which had flat ends (also excluded are the various compartment stock conversions e.g. the "Clifton Downs" and similar stock).

gauge3.info/downloads/hstock.stl



The "upstands" are provided to locate and fix the body end panels.
The holes for buffers will need to be drilled. I have not yet decided on how to source the buffers, so the hole size is not yet known. I will very probably 3D print a pattern and have them cast.

NEXT UP : The Gangway End

[LankyTank]

I keep looking for the 'LIKE' button......

John, for those of us who are not, and unlikely to be, 3D printer enabled - can you advise if these printed items are going to be made available for coin of the realm?

I've got an idea that if I use the Jenkinson techniques ('flat' plastikard sides/ends) allied with the Candy bits, it might just be do-able - maybe....?!?

Keep going, I'm liking what I'm seeing.

Barry

[John Candy]

Barry,
I had already been thinking about how those without the necessary equipment would participate in the project.
I don't have the time/machine capacity to produce items to sell but, with the necessary files being provided, there are companies which will print/laser cut to the customer's requirements.
It may be that one (or more) of the G3S members who already produce items to sell would be willing to add the components to their inventory.
Regards,
John.

[John Candy]

Interlude : Here, while the printer munches its way  through the queue, are some I made earlier!

Bogies : GWR Equalised (frequently referred to as the "American" bogie).

Introduced by Churchward (after a visit to the USA) and used under a wide range of GWR coaches  (both as original fitments and as replacements for older designs when undergoing repairs) they were made in both 8ft and 9ft wheelbase versions.

Diagram "Q" and "U" auto trailers were among those fitted with the 9ft type from new.

The item produced here is a 3D-printed cosmetic overlay for the bogie (details of structural components will be covered later).

http://gauge3.info/downloads/GWRAmerican9ft.stl

 

and the axlebox

http://gauge3.info/downloads/GWRaxlebox.stl

 

I have also prepared files to produce the 8ft "American" and 7ft "Collett" types and these will be made available as other GWR coach types are introduced during this series of articles. A 59ft 6ins "matchboarded" auto trailer (to diagram "Z") is also in the pipeline and this will require the Dean 8ft 6ins bogie.

I am looking at "Dreadnought", "Concertina" and "Toplight" corridor stock as future projects.

John.

[Nick]

There are indeed plenty of companies that will manufacture parts from a supplied solid model file. An internet search will find them. That is what I did when I was looking for laser cut steel parts and 3D model parts in "hard" plastics. Focus your attention on those that allow you to upload a file and give you (almost) instant feedback on cost and any potential manufacturing concerns or problems. Avoid those that ask you to make a phone call or email first. The idea of talking to a human is attractive to some, but it adds to their overheads and means they are likely only interested in large company orders, not small orders from hobbyists. Everyone offers discounts for quantity, so consider if you can share an order or just stock up on enough parts to build a whole train. Oh, and avoid those who make parts and ship from abroad. You will get caught for VAT and import duties and will probably face several weeks delay (don't ask how I know).

Nick

[John Candy]

Part 4 : The Gangway Connector End.

This module applies to all the diagrams with a gangway connector (note the maximum permitted length of a "set" was two cars, so no trailer was fitted with connectors at both ends). When a train consisted of more than two cars, the loco was  "sandwiched" between  a maximum of two trailers either end (the reason being that the regulator linkage was mechanical and would otherwise become too heavy for the driver to operate).

There are three files (LH/centre/RH)

gauge3.info/downloads/gwayendLH.stl
gauge3.info/downloads/gwayendcentre.stl
gauge3.info/downloads/gwayendRH.stl

IMPORTANT NOTE : Although the LH and RH components may look identical to the driving end components THEY ARE SLIGHTLY NARROWER since the centre section was wider than at driving end to accommodate the gangway .... so mark when you have printed so as not to get them muddled during assembly.

The photos show the three panels as printed (not yet fettled) and test-fitted to the headstock.




Prototype Note : Although built with end windows in the non-driving ends, many had the end windows plated over in later years (see photos of your chosen trailer).

NEXT UP : The Non-gangwayed End (driving/luggage compartment)

[John Candy]

Part 5 : The Non-gangwayed End (driving/luggage compartment)

This module applies to numerous diagrams with panelled ends and was fitted to both driving cab ends and luggage compartments.  Although built with windows in the non-driving ends, some had the luggage end windows plated over in later years (see photos of your chosen trailer).

There are three files (LH/centre/RH)
gauge3.info/downloads/drivingendLH.stl
gauge3.info/downloads/drivingendcentre.stl
gauge3.info/downloads/drivingendRH.stl

IMPORTANT NOTE : Although the LH and RH components may look identical to the gangwayed end components THEY ARE SLIGHTLY WIDER .... so mark when you have printed so as not to get them muddled during assembly.

The photo shows the three panels as printed.



Diagrams "Q" and "U" each require one end of this type (either end in "Q" and driving end in "U").

NEXT UP : The Internal Partitions

[hornbeam]

Coming along nicely John, it's a 'gap' in my fleet so will watch with interest.

[John Candy]

Part 6 : The Internal Partitions.

This is where it becomes a little complicated!
There were partitions with a single sliding door and others with double sliding doors.
To make matters more confusing, whereas the planking on the passenger saloon side of partitions was always horizontal, that on the driver's side of the same partitions was, in some cases, vertical!

There are three files:-
gauge3.info/downloads/passengerpartition.stl
gauge3.info/downloads/luggagepartition.stl
gauge3.info/downloads/driverpartition.stl

While the drawings and narrative/ photos are not particularly clear on the precise internal arrangements, I believe the following is a reasonable interpretation of what is available.

Diagram "Q" requires 4 x passengerpartition.stl
These are glued back-to-back to form two partitions (separating end vestibules from the completely open single passenger saloon).

Diagram "U" requires 5 x passengerpartition.stl + 1x driverpartition.stl + 2 x luggagepartition.stl
These are paired/glued back-to-back as follows:-
(a) driverpartition+passengerpartition (dividing driver's cab from passenger saloon)
(b) + (c) passengerpartition+passengerpartition (providing two partitions separating centre entrance vestibule from the two adjacent passenger saloons)
(d) luggagepartition+luggagepartition (dividing passenger saloon and luggage compartment)

The photos shows the three types of panels as printed (sequence : passenger/luggage/driver)



 



NEXT UP : "Walkover" seating.