Background

Dougal is a small 0.4.0 wing tank built by Andrew Barclay in 1946. It formerly worked at the Provan gasworks in Glasgow and now resides on the Welshpool and Llanfair railway (W&L). Compared to other locomotives on the railway it is tiny but this doesn’t prevent it from hauling occasional passenger and freight trains during special event. Indeed, a trip behind Dougal is always a highlight of the gala for me. From the balcony of the Zillertalbahn coaches, the chimney is actually below you resulting in an interesting trip when running bunker first!

The model

Having grown up in Llanfair Caereinion, I have a great interest in all things W&L and have always wanted a modell of Dougal but as far as I’m aware none has ever been commercially produced in 16mm scale. I’m a member of the Cardiff Model Engineering Society (CMES) which has a small garden railway group. We meet every week and either work on the club track or convene at master builder Tony Bird’s house  where we all have individual projects.  Since I joined I haven’t had a project as such but after having a few discussions with Tony and others, it seemed that a model of Dougal would be an ideal project.

A few options were looked at. Scratchbuilding the whole thing was a possibility and with Tony’s help, eminently achievable but as we only meet for 2 hours a week it would take a long time to complete. I then looked at using a steam motor and building the model around that but the work involved in constructing the rest of the loco was time consuming and being impatient I wanted something I could be running relatively quickly.

So, my thoughts turned to using a commercially available model as a basis. I discovered that the Accucraft Ruby had almost the same wheelbase and wheel diameter as Dougal and being relatively cheap appeared to be just what I wanted. I didn’t realise however, how hard it was to get hold of a reasonably priced Ruby. No retailers in the UK seemed to stock Ruby’s and very few came up secondhand  and tended to go for more than I was willing to pay. So I looked abroad and discovered that I could buy a Ruby from the USA including postage for less than they were lifted in the UK. The new Ruby’s have the added bonus of being fitted with the larger Edrig style cylinders resulting in much improved performance.

One of these was duly purchased and arrived after a couple of weeks. I soon had it unwrapped and running on blocks in my garage. Everything seemed ok so I headed outside for a test run on my line. Being manually controlled the run wasn’t very relaxing but it showed that Ruby was free steaming, powerful and easily capable of hauling the sort of trains that Dougal runs with in real life. 

I also took it down to the CMES track at Heath Park during a public open day where it ran impeccably with running times nudging 30mins and the equivalent of a full length W&L train on the drawbar. Satisfied that it worked ok, I started to dismantle the loco to get a better feel for its size.

The Build

I had prepared a number of drawings a varying scales in an effort to get the right look with the finished model. At 16mm scale the Ruby wheelbase was slightly too long so rather than have a larger wheelbase and scale body which to my eyes looked wrong, I scaled the whole drawing up to 18mm scale to suit the wheelbase. This made the whole machine larger but not so large that it looked out of proportion. This wasn’t intended to be a scale model as such, but getting the proportions right was important.

The next step was a simple cardboard mockup of the tanks and bunker to 18mm scale. To me this looked right and when positioned next to my Accucraft Countess, it still looked suitably diminutive. So, enthused that I had a plan, I headed down to Tony’s house one evening.

Comparing the chassis to the drawing, it was clear that a few things would have to be either moved or replaced. The gas tank was way too tall and the regulator fixing was far too large. The boiler design was most unfortunate however. It had two take offs, one for filling and the other for the safety valve, both of these being disguised by large domes. Unfortunately neither of these domes matched the location of those on Dougal and I had resigned myself to the fact that this was something I would have to live with. Tony however, having studied loco and drawing for a while, proclaimed, “we’ll just make a new boiler, it won’t take too long”. Having no experience of this, I obviously hadn’t planned anything on this scale but Tony assured me that it would be far easier to build a new boiler than try to modify the turreted take offs on Ruby’s boiler. So it was decided this was the way forward and dismantling of the loco began in earnest.

The loco was completely taken apart until just the frames and wheels remained. Dougal is a very simple looking locomotive, with everything fixed top the same running plate. It is also all at the same level so the first thing to do was to construct this. A piece of steel was found and marked out to match the width of the cylinders and the length of the drawing.  The actual Ruby frames are slightly too long but removing a short piece of these from the rear would have no structural effect so the frames will eventually be shortened.

On Ruby the steam pipe runs from the regulator to the cylinders underneath the boiler, there is no superheating. The piston reversing valve is situated directly below the steam pipe which restricts the amount of adjustment that can be made to the position of either of these. The centre section of the footplate was removed to allow for the steam pipe and reversing rod to remain in place.

A pair of frame spacers were machined from steel, tapped to accept the screws through the frame and were fitted front and back. This sounds simple but it was the first time I’d used a lathe since school and therefore took a lot longer to produce than I expected. It’s a tremendous feeling to actually produce something though so it was definitely worth the effort. The Ruby frames were slightly too long compared to the drawing of Dougal so about 10mm was cut off the rear of the frames and brad new buffer beams fitted front and back. Accucraft choppers were fitted by being screwed straight through the buffer beams into the frame spacers.

As Ruby is a bar frame loco, the chassis is very see through compared to the chassis on Dougal. Therefore, the final job to do on the chassis was to fit a couple of pieces of sheet steel at the rear to represent the frames of the loco. Once this was done, the chassis was essentially finished.

Whilst this work was going on, I bought the equipment necessary to fit the loco with radio control. Two micro servos, a mini receiver and AAA batteries were purchased and these were trial fitted to ensure that radio controlling is feasible. Luckily Dougal has two water tanks and two bunkers, essentially four boxes in which to put things like servos and the like so fitting them in shouldn’t be a problem and they should also be pretty invisible.    

With the work on the chassis finished, attention turned to the boiler. Building a boiler is something I have never done before, in fact I hadn’t even contemplated it so I was completely in Tony’s hands at this stage. A design was drawn up that provided as much water space as possible in order to prolong the running time. One interesting result of this is that the loco will have a steam dome where the regulator take off will be, exactly like a full size loco, it looks complicated but I’m assured it will work! A piece of copper pipe of suitable dimensions was found along with a smaller piece of copper pipe for the flue.

The first job was to cut the boiler to the right length and then square the ends off. So it was onto the lathe again to get this done. Next, the tubeplates were formed. This was done using copper sheet, cut into a circle and then bashed into the correct shape around a wooden former, the copper having to be annealed a few times to get the correct shape. Again, it sounds pretty simple but cutting two circles of copper, making the former then shaping the metal took the best part of three weeks. 

Here's a shot of Dougal with the sloping water tanks. Not sure when this was exactly but I would guess around 1993ish? I think it looks better with the square tanks.