How to adapt Hornby's Salt PGA wagons

25 June 2021
When a model isn't available in kit form, or produced by manufacturers, a similar RTR wagon is a good base for heavy modifications, as Michael Russell elaborates.

Sometimes when modelling a specific location, you need items that aren’t available off-the-shelf or in kit form. This is where more advanced modelling skills are required because you either have to scratch-build or adapt existing products. The bulk salt wagons required for the BRM 'Runcorn Salt Union' project layout are a good example – nothing is available RTR.

For this project, the starting point is the Hornby (ex-Lima) PGA stone wagons, which are adapted to make Procor 51T PGAs. Some lengthening is required and the wheels, end platforms, couplings, ribbing and buffers all need attention.

There are three ways of making the wagons. You can use fewer cuts to make one wagon out of two, although this is wasteful of material. You can also make three wagons out of four, if you retain the centre hopper divider of the Hornby models. However, I have chosen to make two wagons out of three, by removing the centre hopper divider and replacing it with a piece of plain hopper from a donor, extending the body at the same time.

Shopping List

Hornby (R6829) hopper
wagons and (R8097) three-hole disc wheels

MJT (2352) BR cast wagon buffers

Accurascale (AC2016) Instanter couplings

Phoenix Precision Superstrip 2 paint stripper

Master Prime and Modeller’s Prep-Set

Plastruct (90501) 1.2mm angle and 0.8mm styrene sheet, Evergreen (120) 0.5mm square, (242) 2mm half round, (102) 0.25mm x 1mm strip and (132) 1mm x 0.75mm square

Slater's Plastikard 0.020in and 0.060in plastic rod

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Take the wagons apart to component level and save all the pieces. The chassis is separated from the body by inserting a flat-bladed screwdriver and levering gently from either end to break the glue. Remove the two metal weights.


Use Phoenix Precision Superstrip to remove the paint from the models by immersion. Ensure that you observe all the health and safety advice on the website. Leave the model in the mixture only for the minimum time required to strip the paint.

Lengthening the bodies


The bodies are cut to remove the divider from one hopper, replacing this with a plain hopper section from another wagon. The body needs to be 8mm longer than before.


Cut the hopper divider section so that 10mm of material is removed. Cut the other two pieces to be 18mm long, so that you get the length correct when they are spliced into position.


The wagon bodies were too tall for my mitre box, so I made a jig from timber to start the cuts off. Swap to a mitre box as soon as the cut is of sufficient depth.


Remove mounting lugs from the bottom of the donor section and ensure all cut ends are square. You may have to spend time filing the surfaces so they mate together well.


Cut and file off all traces of pipework from the outside of the hoppers. Use a rotary tool with a router bit for the hopper ends, ensuring that you wear eye protection.


Glue the hopper pieces together using Poly Cement and clamp the sides so that they are straight. Work on a flat surface to keep the body aligned correctly.


You will have to do some filling. I used Finescale Model World Master Prime and its Modellers Prep-Set. It is not easy to achieve a perfect finish on a shape like this, especially at the hopper ends where the access is limited.

Chassis changes


Use a razor saw to remove the coupling housing and the buffers, being careful not to damage the steps. File the buffer beam flat and smooth.


Cut a chassis into three parts and place on a lengthened, inverted hopper. Cut out two pieces from a second chassis to fill in the two gaps. Glue together, ensuring you don’t stick the chassis to the body.


Drill and cut out the plastic surrounding the discharge mechanisms. Be careful as these are delicate items and are easy to break. This is worth doing as it makes a big improvement to the appearance.


Mark out and drill holes in the buffer beams for the buffers and couplings. Tidy the buffers with a file to remove seam lines.


The brake wheels are in a higher position than the stone PGAs. Drill the new location and fit a piece of 0.060in plastic rod ready to take the wheel after painting. Fill in the old location with filler.

Body detail


Cut away the platforms ends moulded into the body. The existing platforms are extended to fit into the space created.


Remove the handrails from the end platforms. Use one platform as a donor by cutting it into four and using these pieces to extend the other two platforms.


Glue the original handrails in their new position. Use 0.5mm square styrene to make new centre handrails to match the height of the other handrails and to fit into the space between the ladders.


Add the ribbing at the end of each body using Plastruct 1.2mm angle. You will need three pieces for each end and they should line up with the existing ribbing.


Glue a piece of 0.75mm x 1mm plastic square along the top of each wagon body side, positioned just below the bevel. Mark out the five places on the body for the external ribbing.


Add the Plastruct angle on the body sides. You will need to file a notch about 2mm from the end of each lower piece to cover the change in the body side profile.


Cut small 3mm x 1mm right-angled triangles to fit at the bottom of each rib using 0.25mm x 1mm styrene strip. Glue in place with Poly cement.


Cut 0.8mm plastic sheet the same width as the internal wagon hopper. Then, cut the four stepped shapes out for the top ribbing. They need to be 4mm tall. Glue two back-to-back and file the square profile round.


Mark the position of the top cover ribs on the inside of the wagon hopper. There are four and they are equally spaced. Be sure that these are upright when you glue them in place.


Using the same profile as the top ribs, cut 0.8mm styrene sheet to make the wagon ends. Use 2mm half round styrene to form the edging.


Glue the ends in place. Make new hopper edging from 0.020in styrene sheet, 3mm deep. It is best to measure each wagon individually to take account of variance from the cut and shut process.


Make triangular pieces to cover the wagon ends from 0.020in styrene sheet. Glue in place and file flat with the wagon sides once the glue has set.


Cut the saved end components in two and remount them on the wagon ends. They need to go back on the same ends they originally came from. Fill in the holes from the old mounting positions with rod and filler.


Make 4mm square mounting pad pieces from 0.8mm styrene sheet. Glue a piece along one edge from the same material so that the pieces lie parallel to the solebars when glued.


Take measurements from a wagon and draw a simple template on paper to make the piping. Use 0.020in plastic rod and employ the same material as spacers between the pieces, mounted on pieces of 4mm square 0.020in plastic sheet.


Glue the pipe assemblies to the mounting pads. You can also glue the piping to the ribs for extra strength, taping them in place to ensure consistent spacing until dry. Add 4mm square covers made from 0.020in styrene sheet.

More information

If you enjoyed this practical feature, you'll find a whole host of great practical advice and step-by-step guides in our Techniques section here.

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