How I constructed a Hunslet loco from a Rail-Road cardboard kit

It does sound counter-intuitive to construct rolling stock for an outdoor railway from cardboard, but cardboard modelling has a long history and, provided the stock is not subjected to prolonged periods of damp, it should survive quite well.

The kits currently being sold by Rail-Road Models have been around for several years, being formerly sold by LocoLines. They have a range of models available in both steam and diesel outlines. The kits are available as body shells only or as complete kits with a basic motorised chassis. I opted for their Hunslet loco kit with a chassis which is available in four different liveries.

The kit arrived, comprising five sheets of pre-printed card (attached to 1.5mm mounting board) and a bag of bits containing additional parts such as stripwood for strengthening the model and the motor, battery box, switch, wheels and other items needed for the motorised chassis. There was also a well-detailed instruction sheet.

Although I have constructed kits from wood and plastic and designed and built my own models from plasticard and 3D printed parts, I've never made one from cardboard and so decided to follow the instructions to the letter.

The first step was to spray all the cardboard sheets with varnish to give them a waterproof coating. Plasticote varnish was recommended. I discovered I had an aerosol of this to hand but as it was probably several years old, after spraying one sheet, I switched to my stock of Halfords aerosols. Both seemed to work satisfactorily, though the Plasticote was still tacky after 24 hours and so was given a second coat of Halfords Gloss varnish. Maybe the Plasticote was past its Best Before date!

Once the varnish had fully dried (another 24 hours), I was ready to start construction.

It was reassuring that, as with my own scratchbuilds, the starting-point was the running plate. This was cut out from the sheet, using a Stanley knife with a new blade.

The edges were then blackened using a permanent Sharpie marker pen. I did try using black acrylic paint but found the felt pen was easier to control.

Next, the sides of the running plate were cut from the sheet and their edges blackened.

The were glued to lengths of 5mm square stripwood included in the kit. UHU was recommended, but I decided to use thick (High Viscosity) superglue from Tool Station.

The stripwood was then cut to length, ....

.... before the sides were glued to the underside of the running plate.

So far, so good! Incidentally, the hole for the motor in the middle of the running plate was cut out by stabbing the blade of the Stanley knife into the cardboard around the outline of the hole and then carefully joining the stabs together with more stabs and careful cutting.

The next job was to cut out the front and rear of the cab. As far as I could see they were identical.

The spectacles were cut out in the same way as the hole in the running plate, using a series of stabs with the blade and joining them together.

Although this produced a slightly ragged hole .......

.... once the edges were blackened, it was hardly noticeable. If I was going to make another model using card, I would invest in a 17mm diameter leather punch (I see they are available on eBay and elsewhere).

The sides and associated reinforcing strips were then cut out.

Reinforcing strips were glued to the front edge of each side, leaving a 1.5mm gap between then strip and the edge.

An offcut of card was used to ensure the gap was the right width.

The sides were then glued to the cab front, ......

..... and reinforcing strips added to the inside of the cab rear.

Two short pieces of 5mm square stripwood were then glued to the inside upper edge of the cab sides, ....

..... before the front and sides of the cab were glued to the running plate, .....

..... using the dotted line on the running plate to ensure it was in the correct position.

The front and rear of the firebox was then cut out, plus two reinforcing pieces. The reinforcement pieces were glued to the back of the outer parts.

The side of the firebox was also cut out before being curved to fit on to the front and rear.

The excess at the base was then trimmed off. 

It was suggested at this stage that the firebox should be glued into place, but I decided to leave it unglued until I was sure I wouldn't need to create access to the cavity inside it for electronic equipment at a later stage.

Attention was now switched to the boiler and saddle tank. Firstly, the sides of the tank support were cut out and corner reinforcements glued into place.

The sides were then linked by spacers glued between them.

The sides and top of the saddle tank were cut out..... 

..... then two pieces of 5mm x 5mm stripwood and two pieces of quadrant stripwood were cut to the length of the saddle tank.

These were then glued together to form the curved edges of the tank.

The sides ........

..... and the top were then glued to the wooden battens.

Before the ends of the tank were glued on, I decided to do my own modification. The ends were supposed to protrude slightly above the top and sides. I decided they should be flush with the sides and end. I therefore shortened the saddle tank assembly by 3mm to make it the same length as the saddle tank wrapper (see below).

The ends were also trimmed and glued to the saddle tank assembly.

The saddle tank wrapper was then glued, firstly to the top of the tank, .......

.... and then to the sides. I used Pritt Stick adhesive for this operation so it would allow me to manoeuvre the wrapper into the exact location needed. I had to extend the ends and sides with offcuts of mounting board by a further 7mm to support the lower edge of the wrapper. I can't figure out if this was because of my modifications or if the lower part of the wrapper is supposed to be unsupported. 

NOTE: On reflection, I would postpone gluing the wrapper to the saddle tank structure until the loco was finished. It's all too easy for the wrapper to be marked with a sticky finger during the construction process (guess how I know this.....).

Two linking plates were cut out and glued to the ends of the saddle tank base to allow the tank to be glued to the tank to be glued to the base. I postponed joining them together until the smokebox was finished, in case some tweaking was required.

The ends of the smokebox were then cut out ........

...... and the supports for the top and sides glued on. I had to trim the sides of the supports to ensure they would fit with a 1.5mm gap all round. Again, I'm not sure if this was down to some mistake on my part.

The top and sides piece of the smokebox was cut and gently curved between fingers ......

..... before being glued into place. The excess at the base was trimmed off once the glue had hardened. Incidentally, I quite often use a Superglue Activator spray during this sort of construction to speed up the gluing process.

The saddle tank was then glued to its base and the smokebox glued to the front of the tank.

The instructions then switched to making four leaf springs. It was suggested that these could be made form card or whitemetal versions could be purchased from Garden Railway Specialists. I decided to make my own using the parts provided.

These were cut out .........

.... and the springs formed from four separate pieces.

The front plates were then glued on ........

...... followed by the end support struts.

The black marker pen was then used to colour all the cut edges/

I decided to wait until the loco was almost completed before attaching them, as they are quite delicate and hence vulnerable to accidental damage.

The rear of the cab was now glued into place.

The cab roof was cut out next and curved between fingers. 

Instead of gluing it to the to the cab walls as instructed, I decided to make it removable. I like to retain access to the cab interiors of my locos so I can add further details, including a driver.

Supports for the roof were drawn on a spare piece of mounting board using the offcut from the cab front as a template.

These were cut out and glued to the underside of the cab roof.

The various parts were now test-fitted to check everything was OK.

Although the body shell wasn't quite complete, I decided to turn my attention to the powered chassis which was supplied with the kit. The piece of plasticard which came with the kit was marked out, following the instructions. This would form the sides of the chassis.

The two side pieces were taped together and the 4mm holes for the axles were carefully drilled to ensure the axle holes were identically positioned on both sides.

The other parts of the chassis were cut out.

The side wings of the gearbox housing were trimmed to fit between the side walls of the chassis and two wooden blocks shaped and glued to the upper side of the gearbox to enable it to be glued to underside of the top of the chassis, ......

The various parts of the chassis were glued together.

.... and the wheels fitted.

The chassis was then test fitted. 

Before giving the loco a test-run I needed to find a way of fixing the boiler and firebox to the running plate. The instructions suggested they should be glued into place, but I wanted them to be removable so I could access the battery pack and any electronics I might want to install in the future.

I cut a couple of pieces of 5mm square stripwood and glued one at the front underside of the smokebox .......

...... and another at the opposite end of the boiler support.

A third piece of stripwood was glued across the middle of the firebox.

Screws were then screwed through the underside of the running plate into the wooden battens to fix the firebox and boiler in place.

The Plastruct tube supplied for the chimney was painted black and loosely fitted into the top of the smokebox.

The leaf springs were also glued into place.

The motor was wired-up to the battery pack. Instead of the SPDT slide switch supplied with the kit, I wired in a DPDT toggle switch to act as a reversing switch.

The battery pack was placed in the boiler and the boiler .....

..... and the switch mounted on the side of the boiler support.

The motorised chassis was connected to the wiring inside the body with a 2-pin JST connector to allow the two to be separated easily.

The motor was then slotted into the hole in the running plate, .....

..... and the loco was given a test run.

The buffer beams .........

..... and cylinder covers were cut out.

The buffer beams were glued to the front .......

...... and rear of the running plate.

And the cylinder covers were glued to the front underside of the running plate.

The parts of the toolbox were cut out and constructed. An additional lid was cut out from scrap mounting board and painted in the same colours as the rest of the toolbox. It was then glued to the front of the running board.

The kit was now complete.

And it was given a run.

As you can see, the loco is a little unsteady. The wheelbase is quite short and, with only one powered axle, the front tends to 'hunt' a little when the loco is travelling forwards. I doubt the loco will be able to pull much of a load, even when she has been ballasted with lead strip.

The motorised chassis is the same as that used in Rail-Road's Wickham Trolley kit. I would imagine it will be well suited for this kit - with its short wheelbase and limited potential for pulling a load. It does seem surprising to me that the same chassis has been used for this loco. The wheels are too small and the wheelbase too short. I could redesign the chassis - extend it to lengthen the wheelbase and use some larger metal wheels with 4mm axle holes which I acquired from Essel Engineering. However, the 3v motor and gearbox will still impose limits on the loco's pulling power and so, instead, I will probably utilise a spare Bachmann motor block which I have to hand - if I can make it fit.

Conclusion

I am in two minds about pre-printed cardboard as a construction material for garden railway locos and rolling stock. The advantages are that it is a familiar and fairly easy material to work with though having the parts pre-printed is, to my mind, a bit of a mixed blessing. It saves a lot of work in finishing off the loco and does provide some very finely finished triple lining, but it makes the construction process somewhat more complicated. Considerable care needs to be taken to ensure that glue is not accidentally smeared on the outside surfaces of the model during the construction process. I do tend to be a bit of a messy modeller and so I'm probably not the best person to use this approach.

During the construction process, I had to make some modifications. In part, this was to make sections of the model more accessible after construction was completed but also there were some parts which didn't seem to fit together cleanly without some adjustment. There are also some sections of the loco which are quite flimsy - the support for the saddle tank, for example. I would feel a lot happier if this had some extra reinforcement - something which I will add in my planned rebuild.

I found the construction process to be informative. Having constructed this kit from card, I think I might now be able to make a better one. I just can't decide whether the advantages of being able to pre-print the final livery on card outweighs the sturdiness of my preferred loco construction material - plasticard.

This month's Garden Rail magazine (Feb 2023) includes an article from a contributor describing the process he goes through in constructing his locos from card. He describes using a computer controlled cutter and then laminating several layers. He also spray paints his models once they are completed. This approach would appear to overcome some of my reservations in terms of finish and robustness. I have been fortunate enough to buy a secondhand card-cutter on eBay and am in the process of figuring how to use it (it came without a manual - but it was very cheap!). Fortunately, it will also cut thin plasticard so, if I run into problems with card, I do have an alternative use for the cutter.

As they say, watch this space!