The ‘tilt wagon’ seems to have been a popular design in early broad gauge (BG) history but I hadn’t got round to building a model before now. A very few of these wagons were converted to standard gauge and I did model one of those back in 2014, regarding it as an interesting curiosity!

 

In the early days, it seems that most goods (and 3rd class passengers) were carried in open wagons but a growing need for weather protection led to the addition of canvas covers, known as ‘tilts’ (from an Old English word ‘teld’ meaning tent). Hoops were fitted, to support the canvas, and some wagons had raised ends to provide a more enclosed structure. The late Eddy Brown collected information about these early wagons, which is contained in the Data Sheets available to Broad Gauge Society (BGS) members. A review of early BG wagons appeared in the BGS Journal ‘Broadsheet’ no 34 (Autumn 1995), including the following sketches by J.C.Bourne:

 

 

Over the following years, many different variants of the same basic style appeared, produced by several makers, of wood or iron construction, most with 4 wheels, although larger ones with 6 wheels were also built.

 

These wagons became very popular and were used for many different purposes, including carriage of livestock. Evidence of this usage is seen in the lime-washed wagons photographed in the Swindon ‘dump’ after the broad gauge ended in 1892. Overall, the following photograph shows that there was a great range from which to choose, for model-making!

 

Broad Gauge Wagons at Swindon ‘Dump’ 1892

 

Several ‘standardised’ wagons, of all-iron construction except for a wooden planked floor, were built in two batches between 1853 and 1854 by various builders. The wagons were generally l7ft. long with side-doors. The inside width was either 9’ 9” or two inches wider. The wheelbase was 9’ 9” in all cases. They had 3’ long springs, set behind the axleguards, with 3’ 6” wheels and Normanville high-filler patent axleboxes. Drawing NRM 4832, below, does not show brakes but they may have been fitted at some stage.

 

 

This old drawing is rather distorted but there is a better version in Alan Prior’s book ‘19th Century Railway Drawings’. Thus, I had the basis for constructing a model by following my usual method of copying over a printed drawing using ‘Fusion 360’ software.

 

My 3D-model of an 1850s Tilt Wagon

 

The chassis was a direct copy of the one I designed previously for my 12-ton coal wagon, of which the prototype was built to the same specification as the tilt wagons of the period. I had to lengthen the ends a little, to match the body of the tilt wagon, but this was a simple adjustment in ‘Fusion 360’.

 

My 3D-model of the Underframe

 

Although these wagons used smaller (3’ 6”) diameter wheels than the 4’ wheels of earlier versions, it was still necessary to provide apertures in the floor, for the tops of the wheels to protrude into wheel boxes.

 

 

Printing my Model

 

As I reported in my previous post, I am now using a ‘Prusa Mini+’ printer to create my models. As well as learning about the printer itself, I have been learning how to use the associated ‘Prusa Slicer’ software, which has several differences from the ‘Cura’ software that I used previously.

 

‘Fine Tuning’ the printer

 

Fortunately, the printer itself is so smooth and quiet in operation that it seems to encourage experimentation, so I have been trying out various software settings in order to improve the performance, particular in respect of ‘stringing’ and ‘oozing’ of filament, as the print head moves between different areas of the print.

 

Filament stringing around printed edges

 

Although, when using my E180 printer, I frequently saw straight lengths of filament along lines where the nozzle had transited between different parts of a model, I have not seen this gossamer-like ‘fluff’ before and shall be interested to receive any comments from others who may have experienced this problem.

 

It’s fairly easy to remove, by rubbing with fingers and an old toothbrush but, although I have reduced it considerably by adjustments to temperature and retraction distance, I have not yet eliminated it entirely.

 

Tilt Wagon on Printer Bed before Cleaning

 

I found that a useful tool for removing the ‘gossamer’, without damaging rivet detail, is a silicone rubber shaper, intended for controlling painted edges.

 

Artists Silicone Colour Shaper as a Cleaning Tool

 

Incidentally, during the course of my experiments, I suffered a break in the filament, as it loaded from the spool. The sensor, which I had bought as an optional extra for the printer, immediately detected the break and paused the print. The LCD screen displayed instructions for re-loading the filament and the print then re-started from where it had paused, without a hitch.

 

Print ‘Quality’ Settings

 

The layers of print produced by the Mini+ were noticeably more even than those from the E180. This very even-ness, however, made them more noticeable under close examination. At the 0.15mm ‘QUALITY’ setting for layer height, the layers are clearly visible in the close up photos below. There is also noticeable ‘trailing’ of filament around raised details. By changing to the 0.1mm ‘DETAIL’ setting in the slicer software, the printed layers blended together and, perhaps more importantly, the rivet detail was more cleanly defined. There is still a little ‘trailing’ but this is not noticeable under normal viewing conditions. These are unpainted surfaces with no additional surface smoothing after printing, apart from removal of the ‘gossamer’ referred to above.

 

Close-up Comparison of Two Quality Levels

 

 

Preparing the Model for printing

 

I often like to break a model down into separate components, both to reduce individual print durations and to allow optimum positioning of components on the printer bed, to reduce the need for additional support structures.

 

This particular model presented difficulties in adopting this approach, because there are very few flat surfaces, apart from the floor, while the ‘bonnets’ at the ends have substantial overhangs under the curved canopies at the top. I did initially try printing the sides and ends separately but it proved awkward to assemble the resulting parts neatly, so I thought I would risk printing the body all in one piece and see how well my new printer coped with the overhangs.

 

I should not have worried, since the body printed cleanly and accurately. This, in the end, was by far the simplest and most satisfactory solution! There was still some fine ‘stringing’ of filament, appearing rather like spider webs between isolated structures, such as the ‘strouters’ (posts) that support the iron sides of the prototype. These fine strands of filament were easy to remove but I am hoping that further adjustments to the printing parameters will eliminate this minor problem.

 

When I placed two models together, one printed with 0.15mm layer height and one with 0.1mm height, the quality difference is barely visible and would probably disappear under a coat of primer and a final coat of paint. There are still some whiskers of filament that need to be cleaned off before painting.

 

Two models printed to different ‘quality’ standards

 

There is a significant difference in the times taken for these two models to print. The 0.15mm resolution print took 1h 30m whereas the 0.1mm resolution tool 2h 40m. Whether this difference is significant depends, perhaps, on the overall size of the model and for small items such as these, I did not feel it was any hardship to adopt the finer quality.

 

The following picture shows the complete model, with both body and chassis printed at 0.1mm ‘Fine’ quality. I have added wire rails between the ‘strouters’ or posts.

 

My 3D-Printed Tilt Wagon + Chassis before painting

 

Mike