Raymond Walley
In the third instalment of the description of his build of MOK’s highly detailed kit, Raymond completes the loco body, applies the brakes, then concludes with a successful run on the test-track
See also Part 1 and Part 2
Ian Rathbone concludes the series where he describes painting the finished model in Part 4

The cab goes together very easily and, as usual, all the parts fit first time. The unit then slides into the footplate from underneath. The tabs allow precise positioning and a trial fit before finally soldering together. Once the two units are assembled they are then ready for the cosmetic sides to be fitted, which are also tabbed for precise alignment. Suspension parts

Preparing all the parts for the hornguides takes a little while since there are many holes to be opened up and tapped. The springs come with the hangers cast in place and are a little too fat to take the dampers.

I decided that I wanted the dampers to be removable anyway, not glued in place, so I cut off the hangers, carefully drilled out the spring leaf ends and soldered in some 1mm nickel rod threaded14BA instead.

This is not nearly as difficult as it sounds. The picture left shows all the parts bolted into place. It is important to ensure that the springs go in the right place, those at the rear have more leaves and bigger dampers that those at the front.

After several weeks break due to other commitments I got to grips with the smokebox and firebox, both relatively simple, and the boiler, which required several annealings to persuade it to fit together. The instructions for the firebox are to remove the two lower tabs at the rear where it fits to the cab front because otherwise it is almost to impossible to fit due to the tabs on the bottom of the fire box needing to be seated first. I did not cut them off completely but left a vestige, which helps to seat the unit on the cab front and gives a positive ‘click’ once it is seated correctly. Boiler, firebox and smokebox components

Pictured above are the three units ready for the next stage:

• The boiler has the saddle fitted to take the dome, which is secured with a 6BA bolt.
• The firebox has the safety valve fitted on to which is pegged the safety valve bonnet,held in place with a sliver of Blu Tack, as is the lubricator on top of the dome.
• The brass disc is fitted between the firebox and boiler and is removable for polishing.

David at MOK rang me the day after I had restarted work to warn me that the holes in the cab front where the handrails enter the cab were probably in the wrong place. The holes are too high by 3.5mm. Fortunately I had not yet fitted the splasher tops or altering the holes could have been a little problematic.

The holes were filled and new ones drilled at the correct height. No doubt, future versions will be corrected. The handrail knobs were all replaced with nickel silver ones from Markits.

The picture at the below of the page shows the boiler now soldered to the firebox, the chimney soldered in place and the dome and safety valve bonnet polished and fitted along with the brass ring between the smokebox and boiler (the safety valve is incorrectly aligned, corrected later). At this stage the lower portion of the boiler between the centre splashers is removed but not the base of the transition ring. Assembled boiler, firebox, smokebox

An area of some little concern was the smokebox. For the brass disc to be removable, the 6BA bolt between the smokebox and boiler needs also to be removable. Leading on from a method on the Piercy J27 I built recently, I considered that it ought to be relatively easy to arrange for the door to be removable. Well it was; by carefully drilling out the rear of the boss of the dart to take a 12BA bolt, soldered in place with the head cut off and the end dressed. Then a substantial piece of brass, suitably drilled and tapped, was soldered in behind the door. There is sufficient flexibility to ensure that the dart will always be correctly aligned when tightened. It is now possible to remove the door for access to the 6BA bolt joining the smokebox and boiler.

These are intended to be glued in after painting but the joint will depend only on the junction between the seat of the valve and the boiler side. The instructions also suggest using some tube to mount the clacks and the Roscoe valves.

Not having any suitable tube to hand, I used some 3mm rod cut a fraction longer than the width of the boiler and drilled out the ends 1.7mm in the lathe. Valves in place on boiler

This made a nice firm fit for the spigots. It was then soldered in across the boiler after opening out the boiler mounting holes, and the ends dressed. Both clacks now fit firmly without glue. The Roscoe lubricators could not be done this way as the tube across the smoke box would have made removing the holding bolt impossible to get at so I soldered some 2mm brass square section rod across the holes inside the smoke box. Then, very carefully, the hole was drilled 0.8mm to take the spigot on the lubricators. The Proxxon drill press came in very handy.

The picture above shows the splashers ready to be fitted, having been through the rolling bars along with some of the beading. The beading needs to be the exact length of the splasher so I measured the brass wire against the splasher edge that faces outward and then ran them through the rollers.

However, that did not work well because when I came to offer up the wire later, it was a fraction short so it was back to trial and error to get the length right. It is important also to file the ends at an angle to fit flush with the footplate.

Were I to build another I would file notches in the footplate where the beading meets it so that the pre-rolled wire could simply be fed in place and cut off underneath later (having suggested this to David it may be an etched feature in future batches). It would also make fitting the beading slightly easier but the designer has anyway produced an elegant method of achieving this. The splasher sides and top when fitted produce a step into which one fits the wire; with plenty of flux, the heat from the RSU tip then draws the solder used to fix the splasher tops into the beading joint.

The only place this does not work of course is where the splasher sides cover the cab but a few dabs of solder cream did the job.

The picture above shows how neat the completed job is when finished.

A pleasant diversion for an afternoon or two can be the simple task of getting small castings ready for use. The best example of this is probably the backhead as it usually involves some complex work drilling out all sorts of holes and inserting various strands of copper wire. This backhead is no different. Many holes needed drilling and, for once I managed the lot without breaking a single drill bit. The new Proxxon drill proved useful in cleaning up the parts using a circular brass bristled brush. Trial fitting

Here are parts now fitted and ready to try out in the cab. The gauges are attached to the backhead by soldering their pipes in place. The parts were temporarily fitted in the cab, only the pep pipe tap was fixed, the rest will be glued in after painting. If the reverser is soldered in place now it effectively prevents the backhead going in once the roof is added.

I gave some thought to ballast while it was still relatively easy to access the inside. There is not a great deal of room inside the engine to fit much lead but if the finished engine is as well balanced as it seems it will be, not much ballast should be required. As noted earlier, the ashpan is full of liquid lead. The firebox is quite roomy and the motor takes up less than half the width so I used lead flashing shaped to fit round the wheel arches and bent to fit the contour of the firebox. I made four since there is room for them and four more pieces were shaped to fit in the rear portion of the boiler. All eight pieces were glued in place with UHU. I managed to get about four ounces in this space.

I also added liquid lead inside the backhead and went back and added more to the ashpan by shuttering off the space for the motor and filling the remaining space to the top, increasing the weight by more than 50% in this area. All this weight is directly over the driving wheels and the centre of gravity is still at the centre of the engine. A little more ballast was added by filling the sand boxes with liquid lead too.

Brake hangers and rodding before fitting Brakes and rodding in place Sandpipe Underside view of coupled engine and tender

I took the as yet unpainted loco to the Epsom club's test track to see how it would perform in the real world and to find out if it would pull more than the skin off a rice pudding. Despite my cock-ups during construction it ran like a sewing machine, which was most gratifying.

The bogie guides the engine through curves very well indeed and allayed my fears about tight clearances. It also pulled three heavy but free running bogies and a long rake of Ian Hopkins scratch-built fourwheel coaches. A little more lead over the drivers will improve on that and enable it to haul prototypical length trains.

Since the bogie clearly supports its share of the weight I shall try inserting shims in the mounting to raise the front fractionally. This should shift a tad more weight over the rear drivers. That's the theory anyway as expounded by Doug Thomas, who has far more experience in these matters than I. Finally, I must apologise for the poor quality of the two photographs at the test-track, they were the best I could do with a mobile 'phone. Ian Rathbone is preparing an article on painting and lining Raymond’s loco which will follow soon.