Constructed in brass from a single 1926 photograph

It is 1st of June 1926, and a brand-new tippler empties a coal wagon at the Portsea Island Gaslight Company, Portsmouth, while local dignitaries look on from clean coal wagons.

Note the elevated control box and the lack of railings around the platforms and ladder, which runs from the door to the access above.

In operation a loaded wagon is either pushed by a locomotive or pulled by a land-mounted positioning/indexing system into a cylinder called the barrel. The barrel then rotates the wagon to an inverted position, which empties the wagon’s contents. The barrel next returns the wagon to the upright position and the positioner feeds the next wagon into the barrel.

There are many videos on YouTube of tipplers (US: rotary dumpers) in operation, both model and full size. Tipplers are preferred to hopper cars due to their lower center of gravity, more thorough emptying, no complicated bottom openings and less costly construction. The only hopper in the system is the land mounted one beneath the tippler deck.

Starting the project, it was obvious that a printout to approximately O scale dimensions would be a good thing. I fired up the iMac and put my trust in WYSIWIG to give reasonable results. I printed off a copy and used it to lift off all the angles and measurements.

The drawing summarizes the dimensions of the tippler barrel based on the photo and some Internet searches. It represents the choices made which, while they reflect most on the design decisions of the bespoke tippler, they also reflect on my budget; namely, K&S tubing comes in 12-inch lengths and my choice of barrel length was 5 ½ inches. Therefore, there is very little waste. Furthermore, the rounded corner rectangular tubing is not available to the modeller, but round tubing is easy to obtain and install. Again, 12 inches long for two lengths of 5 ½ inch.

Four end rings are needed. The holes are drilled, and the brass sheet is secured with a screw through every hole, all the way around. This prevents the ring buckling while it is being machined.

Prior to cutting out a ring in the lathe, the brass square sheet is painted with Layout Dye, a blue-coloured alcohol-based dye. This is also known as Marking Blue. A spirit-based felt-tip marker makes a suitable alternative for occasional use. The solvent evaporates rapidly after brushing on and then I scribe it with a sharp, pointy rod. Mistakes are easily fixed with a new coating of dye. For some strange reason, the dye washes off rapidly from the metal but not out of clothing. When all four rings were cut out, I remounted them on the faceplate jig and turned them all to the same diameter.

Above are four rings, drilled and ready. The hole positions are estimated from the photo at the beginning of this article and as can be seen above, the centre disk bears the radial scribe marks.

• Inner Diameter: ID = 3.50 inch (89mm)
• Outer Diameter: OD = 4.25 inch (108mm)
• Ring Width: 3/8 inch (19mm)
• Thickness: 1⁄16 inch (1.0 mm) or so.

The next step is to build a jig to keep the ends square and concentric. The overall length is 5½ inches and the length between inside of the end rings is 4 ¾ inches. The jig needs to be square, level and parallel. I worked towards tolerances of 0.010 inch and 0.1 degree. These are easily obtainable with most DIY equipment and patience. Any inaccuracy at this stage results in a frame which may not work smoothly, as errors compound errors.

Sliding a strut tube into two matching end ring holes, I tucked the tube into the corner, fixed the ring to the jig face and soldered. If the jig is square, then the ends are square. I continued inserting in an opposite ring hole pattern, soldering up the job square as I went. Note in the photo the use of large washers to hold the end rings in place for squareness. Once the inside rings were in then the Outside end rings were offered up and soldered.

The threaded rod rotates inside two small pillow blocks, represented by ¼ inch lengths of round tubing. To achieve proper alignment of the tubes between struts, I used a length of dowel socketed into the tubing.

I made the first two clamps freehand. What a mess. I “shoulda” made a jig. I have a lot of “shoulda’s” in my life and this was another of them.

Here is the jig, a wood cutoff from module making, measuring ¾ x 5 x 2½ inches. The layout dye contrasts nicely for the saw cut accuracy wanted here. The slots are wide enough and deep enough to hold the brass tubing snugly during assembly, but loose enough to allow easy removal of the finished article. Here the parts are laid up dry prior to soldering:

Another feature of the barrel not seen in the prototype photo would be access to a wagon or track in the barrel. A reasonable amount of safety would expect something other than an employee balancing on a strut tube, so for my little people I have installed two micro mesh walkways. These are etched mesh, about 25 holes per inch or 625 holes per square inch.

I used a magnetic clamp system to prevent the wagon from losing contact with the rails while tipping. This was tested with a Slater’s wagon and Lee Valley cylindrical super magnets, ¼ x ¼ inch (6x8mm Amazon).

I spent way too much time thinking the clamping system through, and this magnet idea certainly won’t work with anything other than steel wheels, but it works a charm with Slater’s wheels. As the wagon enters the barrel, the magnets grab its wheels, pull it in and stop it right under the clamps, giving automatic indexing.

Two of the four magnets are visible under the walkway in the photo. I soldered in place two short pieces of brass tubing and glued the magnets inside them. The solder and tubing protect the magnets and don’t let them run away but they do not interfere with the magnet action and strength.

Finally, the finished barrel is ready for the painters. I washed it thoroughly with an old toothbrush, using non-scented detergent and very hot water. I rinsed it with isopropyl alcohol and allowed it to dry in a warm area. I used an etching base primer for the first paint coat. </WRAP>

There we have it, all ready for the Great British Train Show earlier this year in Toronto, Canada.