Model Railways: How to make a pre-grouping coach

13 September 2021
These four-wheel coaches are in plentiful supply, though can be upgraded with little expense to make detailed layout-ready models.

The Hornby four-wheel coach is a popular model that is still in production. They are generic in appearance and their design of three doors per side was rare. We had several left over from being used as toys once part of the Thomas the Tank range and decided to see if we could upgrade them to run on a scale model railway. Some drastic surgery was required to make a coach that could pass muster alongside more modern rolling stock, albeit still generic in nature.

It’s quicker to produce several carriages in one sitting by carrying out each stage on a number of examples, rather than producing one finished carriage at a time. However, you may like to produce one example to start with to gain confidence. The axleboxes used were from ABC Models, but similar items are available elsewhere.

Shopping List

  • Hornby (R4673) RailRoad coach
  • Humbrol Poly Cement
  • Humbrol 250 enamel, Humbrol acrylic 33,186 & 67
  • ABC Models axleboxes
  • DMR Products buffers
  • Romford couplings
  • Torpedo vents Wizard Models (51L)
  • Styrene sheet and strips, PVA adhesive, Cyanoacrylate adhesive


Remove the undercarriage by levering the tabs out from underneath with a flat-bladed screwdriver. Remove the weight and the wheels. And then remove the roof by squeezing the ends of the carriage and pulling it off.
How to make a pre-grouping coach


Using a sharp knife and light cuts, score down the body repeatedly to separate each coach into two halves. You can join up the two cuts from underneath using a set square to complete the separation. Patience is required.
How to make a pre-grouping coach


You should be left with these parts. Retain the two larger pieces for this project. Using a sharp knife, remove the body location tags from the underfloor.
How to make a pre-grouping coach


Tidy up the cut ends with a file, add 1.5mm strips of 0.010in styrene sheet and glue the two halves together using the roof as a spacing guide. Use 0.050in styrene sheet to strengthen the floor joint.
How to make a pre-grouping coach


Use a file initially and then 600 grit sandpaper to clear away detail from the carriage ends. Again, patience is needed here to achieve a clean result.
How to make a pre-grouping coach


Reduce the carriage side height by paring away the top 1mm using a knife and then a file. Take your time to avoid taking off too much material.
How to make a pre-grouping coach


Make the roof profile shallower by using the roof from a brake van, or something similar, as a template. Pare the excess away carefully and finish the profile with a file.
How to make a pre-grouping coach


Make three compartment partitions per coach using 31mm x 31mm pieces of 0.050in styrene sheet. Taper these to match the coach interior profile, removing only a little from each side at a time and testing frequently for fit.
How to make a pre-grouping coach


Use the carriage end to get the partition profile correct. Reverse the partitions and place them all together to ensure uniformity. Glue the partitions into place using Humbrol Poly Cement where the large panels between the doors are situated.
How to make a pre-grouping coach


Cut out the pieces for the new frame from 0.040in styrene. You’ll need two side pieces 114mm x 4.5mm. The five cross members are 26mm wide.
How to make a pre-grouping coach


Glue the two sides and two of the cross members together using Humbrol Poly Cement' ensuring that it is square.
How to make a pre-grouping coach


Glue one end in place using a clamp and ensure that it is positioned centrally and at the end of the carriage. When dry, do the same for the other side. Then glue in all the cross members.
How to make a pre-grouping coach


When dry, sand the carriage bottom carefully to ensure that it is level. Do this on 600 grit paper and over a flat surface such as a mirror.
How to make a pre-grouping coach


Glue the brake gear onto the axleboxes and then the bearings into the latter using cyanoacrylate.
How to make a pre-grouping coach


Glue the axleboxes into place using cyanoacrylate after carefully marking the positions beforehand. You must ensure that the bearings are exactly opposite each other.
How to make a pre-grouping coach


Use 0.020in styrene sheet for the roof. Bend the roof to shape by using a former – we found a metal biscuit tin that was the correct diameter. Dip into boiling water for 90 seconds using rubber bands as clamps.
How to make a pre-grouping coach


Make two end pieces to give the roof rigidity and to hold it in place. If you cut these to give an interference fit, your roof will stay in place without glue and can be removed in future for access.
How to make a pre-grouping coach


Add roof detailing. We used torpedo vents from Wizard Models (51L). We also made some oil lamps from styrene and rain strips from Evergreen 0.25mm x 0.5mm strip.
How to make a pre-grouping coach


Cut strips of 0.010in styrene sheet into 1mm strips and add to the carriage ends. Add steps made from the same material. I think four is an ideal number.
How to make a pre-grouping coach


Make or extend the brake ‘V’ hangers and fit a shaft between them using 1mm styrene rod. Use 0.010in styrene strip to represent the brake pull/push rods.
How to make a pre-grouping coach


Add detailing to the solebars by using a 0.010in styrene overlay. You can use a blunt tool to impress rivet detail from the reverse side before fitting.
How to make a pre-grouping coach


Make step supports from 0.45mm brass rod. Make an ‘L’ shape 11.5mm long and solder another piece on 5mm down. Then snip both pieces off about 2mm in length.
How to make a pre-grouping coach


Glue the step supports to the solebars using cyanoacrylate. In general, you need to have a support under each door and one extra at either end of the carriage.
How to make a pre-grouping coach


Make steps 3mm wide from 0.020in styrene sheet and glue to the supports using cyanoacrylate. File cut-outs to go around axleboxes.
How to make a pre-grouping coach


Add a buffer beam made from 0.030in styrene sheet, couplings of your choice and buffers. We used some buffers from DMR Products and couplings from Romford.
How to make a pre-grouping coach


Make handrails from 0.3mm brass rod using a handrail bending jig such as the one depicted from Bill Bedford. The door handles are made by soldering 0.45mm brass rod into a ‘T’ shape.
How to make a pre-grouping coach


Spray with a primer and when dry, hand-paint the carriage interiors. We used Humbrol 250 enamel. Mask couplings beforehand.
How to make a pre-grouping coach


Spray the top coat, but mask the windows to avoid overspray inside. We used Humbrol acrylics 33, 186 and 67 for the undercarriage, carriage sides and roof respectively.
How to make a pre-grouping coach


Drill holes and add the handrails and door handles using cyanoacrylate. Also add the buffer heads as per the supplied instructions.
How to make a pre-grouping coach


Cut the glazing into sections of three windows and glue into place with PVA glue after cleaning with a file. Ensure they don’t foul the roof before gluing.
How to make a pre-grouping coach

How to make a pre-grouping coach

To finish, add weight to the space between the solebars. A product such as Deluxe Materials’ Liquid Gravity is ideal for this. Upgrade to metal wheels if the coaches formerly had plastic ones. Making these carriages is an enjoyable project if you’re not looking for strict accuracy. By looking at photographs of the real thing you can model carriages from many regions and give the look of many pre-grouping companies. There are many sources of parts too; try Wizard Models, Alan Gibson, Phoenix Precision and MJT from Dart Castings. To improve the coaches further, add seating, passengers and lights. These coaches are rather sombre in colour, being intended for industrial use, however, there is scope for some lovely pre-grouping liveries. If you can’t wait for off-the-shelf items to become available and you’re tempted to try a weekend project, why not have a go?

Need more advice? Some of the below articles may help. Also, take a look at the BRM Techniques page for all our latest guides and advice articles.

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