How I drew and 3D printed a Southwold Railway van

The majority of the goods rolling stock on my railway has been bashed from LGB or HLW wagons and chassis to make them look more UK-based. As a consequence, most of my wagons are only vaguely representative of stock which would have run on an English three foot narrow gauge railway.

 

Since buying a (very) cheap 3D printer (under £80 new on eBay), ...

 

  ... I have been steadily developing my skills at drawing my own designs using TinkerCAD (see How I drew and 3D printed some window frames) which covers most of the basic techniques used in TinkerCAD. After having replicated the open wagons (see How I drew and 3D printed my own design of open wagon - pending) which I had constructed from my own resin castings (see How I made my third batch of open wagons) and a luggage van similar to those on the County Donegal Railway (see How I designed and 3D printed a luggage van), I decided to try something more challenging and, more importantly, based on a real prototype.

Drawings of the rolling stock on the Southwold Railway are reproduced in most of the books about the railway. I used those in The Southwold Railway 1879-1929 by David Lee, Alan Taylor and Rob Shorland-Ball, which I photocopied and enlarged. Using a couple of the known measurements on the drawing, I was able to convert all the dimensions into 15mm/1ft scale (1:20.3).

The first job was to draw the solebars for the chassis. The main beam was just an elongated cuboid.

The brackets at each end of the main beam were a couple more cuboid with domed rivet heads strategically attached.

Once one bracket had been drawn it was duplicated and 'Mirrored'. The brackets were then moved to the ends of the solebar beam and grouped to make a single unit. I find grouping objects at regular intervals to be useful as it means the unit can be moved or even re-sized easily.

 The W-irons were a couple of cuboid grouped together, one being rotated (by around 22 degrees I seem to remember). Once one was drawn it was duplicated and then mirrored. The axle box was drawn from four shapes; a (blue) cuboid, a (green) trapezoid (on page 10 of the Shape Generators tab), a (orange) cylinder and a (red) cuboid with smoothed edges. A short 3.5mm diameter vertical hole was formed in the back of the axle box using a cylindrical 'hole' shape for the end of the 3mm axle.

The leaf springs were overlapping 'ring' shapes which were bisected (with an cuboid hole).

The brackets for the leaf spring were made from an elliptical cylinder with a couple of domed rivet heads attached.

Once all the components had been assembled, additional ironwork was drawn on the solebar beam. The solebar was then duplicated and a brake lever added to one of them. This was constructed from a long thin trapezoid, whittled away with various curved hole shapes. The brake shoe plus its actuating arm was drawn separately so it could be glued in place once the wheelsets had been added.

Two spacers were then drawn to ensure the distance between the solebars was accurate for the Lilliput/Bachmann metal wheelsets I'd be using (60mm long for 45mm gauge and 44mm long for similar 32mm gauge wheelsets).

I tackled the sides of the van next - as these are basically a series of oblong boxes joined together. A cuboid formed the side, to which a couple of beams were added, top and bottom.

The divisions between the planking were created by placing a series of thin cuboid 'holes' at regular intervals (using the Duplicate and Repeat tool) across the side and then grouping them with the side to make the indentations.

The vertical beams were then added, together with the sliding door.

The planking on the door was then inscribed as above, ......

 ..... after which, the vertical beams on the door were added.

Angled sections were created above the bottom horizontal beam using wedge shapes, ....

.... and the bevels in the upper beams were made by cutting holes with cuboids which had had their corners rounded.

Finally, the ironwork was added in the form of corner plates and runners for the sliding door, rivets and a triangular canopy over the doorway.

The end of the wagon was created in a similar way, except that the curved section for the roof was made by slicing off a chunk from a large circular disk, made from a flattened cylinder.

 

 The edges of the end were shaped to allow the sides to be slotted into them.

 

Once all the pieces had been drawn, they were exported from TinkerCAD as .STL files and then imported into Cura to be sliced. They were then loaded into the printer and printed out.

Some wedge-shaped corner pieces were also drawn and printed, together with some curved roof supports (created by copying then van end into a new design and slicing its top off ).

The ends and sides were then glued together using thick superglue from the ToolStation website. The roof supports were also glued across the middle of the wagon.

The corner pieces were then glued into a place to act as supports for the floor, which was cut from a piece of 2mm thick plasticard (I could have drawn and printed it, but feel that it's a waste of filament to print out a piece of plain plastic sheet).

One of the solebars was then glued in place, having carefully measured its position (30mm from the centre line of of the floor)

Lilliput 32mm diameter spoked metal wheelsets were slotted into the axleboxes and the other solebar glued into place.

One of the spacer pieces was then glued across the middle of the wagon.

The brake block and hanger assembly was then glued to the floor of the wagon so it aligned with the relevant wheel behind the end of the brake lever.

10mm wide planks cut from 2mm thick plasticard were then glued to the roof. NOTE: I started from the outside edges and worked my way to the middle, so that I could be sure the overlap at the edges was correct. The final plank was cut to the correct size to fill the gap.

A 0.5mm sheet of plasticard was then glued to the roof to give it a smooth finish. NOTE: I cut the sheet larger than was needed and glued it carefully into place by applying liquid poly cement, starting at one side and then gluing the sheet into place in stages. Once the solvent had set, the excess plastic was trimmed off.

3D printed centre buffers were added to the headstocks.

The wagon still needs to have a paint-job (Halfords grey primer as the livery with black acrylic for the solebars).

I addition, I will attach my wire versions of LGB style hook and loop couplings - and then the van will be ready to enter service.

I must admit, I really like the compact nature of this van. It's much smaller than the vans which already run on my railway but I anticipate making a few more of these and steadily replacing my existing stock.

As you can see from the photos, I have done very little smoothing, filling and sanding on the parts. Considering the cost of the printer, I don't think the finish is too bad. 

For those interested in short-cutting the process and making their own models, I have uploaded the all the parts to Thingiverse.

Happy printing

To be continued ........