CF MRC

The reason for this arrangement is the proximity of the slide bars to the rear bogie wheel. On a 4-6-0 there is less of a problem with using a conventional bogie because the overall wheelbase isn’t very long. However, on a pacific the trailing wheels cause an issue in terms of swing at the rear end. That is why Hornby have flange-less Cartazzi / trailing trucks on their pacifics. The coupled wheelbase on a pacific is usually quite short and adding the rear wheel of the bogie doesn’t make the wheelbase unmanageable. If it were on a bogie it would very likely kick into the cylinders and slide bars on a tight curve so they would have to be wider or chewed out at this point. Having that rear wheel horizontally restrained make life simpler - it is what Denys Brownlee did on his Flying Scotsman and I had to do on my Stirling 8’ single - which has virtually no clearance at the front end on the prototype! The front pony on the Skittle Alley can steer round a curve more easily than a bogie would do: the frames will be quite vestigial at the front to allow this to happen. Hope that long winded explanation helps to explain the rationale? Tim

Work has continued on the front bogie / pony truck for the long engine. The rear bogie wheels have a vertical slot to move up and down. The front pony truck started out as a lump of copper tungsten (heavy alloy - upside down in this photo). The 12BA rear pivot and axle hole were drilled in the roughed-out block so that the whole engine could be tried out on my test track minimum radius, before committing too much effort. The test track was actually a section lifted from Chiltern Green forty years ago and is substantially below the 600mm radius on CF. It all fits on the curve, but I dare say there will be some squealing - especially with a solid 1/2” diameter brass boiler sitting over the top. There is a lot of work to finish off the ‘pony’ truck, but at least it now looks a bit more joined up at the front. Tim

I’m not sure that there would be room for two more spokes Jim, if the size is maintained as is. From a conversation I had with Alan Smith, I think there are limitations on the stainless steel 3DP resolution. I also suspect the demand for the 12 spoke wheels would be a bit feeble. Tim

There are an awful lot of spokes for such a small wheel. Tim

There might just be something about 2mm scale modelling in the 3rd programme. Tim

I’m not quite sure the new type 5 wheel manufacturing process is ideal for small diameters (<7mm) as the 3DP stainless steel is a bit heavy around the hub and rim. However, they were just right for the large driving wheels on the Skittle Alley as these locos had thick tyres (I did trim the spokes a bit though). Tim

They are only carrying wheels so no real stresses on them: the brass is also quite a tough alloy. It’s a technique I’ve used for driving wheels and carrying wheels on 2mm locos for the last 40 years, starting with a Johnson Single in 1977, albeit with steel wheel centre spokes. There are lots of plastic-centred loco wheels out there. Tim

The episode on 24th January (3rd) should be a good one… Tim

Well, I changed my mind. The front bogie wheels had been giving me pause for thought as they are of typical NER pattern 12 spoke at 3’ diameter. (Photo courtesy Blandford 1969) The Association only makes a ten spoke wheel at that diameter. There is a school of thought that says you never see the spokes when the wheels are going round. That is perfectly true, of course, but it somewhat irritates me to see the wrong wheels under an engine, especially when they are so characteristic of a particular railway. I have made wheels in the past and was resigned to turning up some steel blanks for the purpose. It then occurred to me that the ten spoke wheel could easily by converted, so eight of the spokes were cut out with a piercing saw: one cut near the hub, the other at the perimeter. The cutting scars were filed away and the hub reduced in size as well as the rim: I wanted the spokes to be as long as possible - many model wheels are too heavy in these areas. The ten replacement spokes were made from 10thou black styrene cut into a small rectangle that was very slightly trapezoidal in shape. This gives just a slight friction fit between the hub and rim. Setting up these spokes was easy, they were in essence a clock face. The penultimate styrene spoke can be seen ready for placement on my finger tip. Once the spokes were in position a minute drop of very low viscosity cyanoacrylate adhesive was flooded into the end of the spokes, using a fine pin. Super glue can be slowed down in ‘going off’ by placing a drop onto a plastic bag to pick up from. Once set, the spokes were trimmed to shape using a scalpel and an ultra sharp chisel. The wheels were then given a coat of NER green: they are looking a bit vulgar in this photo. They will hopefully look better when the rims and hub are black. Worth all the effort? A few hours work - what do you think? Tim

‘Pete the Impaler’? All looking fantastic, Pete. Happy New Year! Tim

After a great deal of fettling and fitting the running plate core is now fixed solidly to the chassis for the Raven NER 4-6-2 class. It had to be lowered quite a distance, compared to the starting position, and was also reduced in thickness by 0.25mm. There are two 14BA fixings, one at the front, one at the rear. The body is live to one side of the engine. It was important that the rear fixing could give stability and so a thin strip of very thin PCB was soldered to the top of the ‘insulated’ frame where the stretcher sat. The fixing bolt was then well greased up (as well as the associated tapped hole) and some cling film wrapped around the body section. Slow setting epoxy resin was then placed on top of the spacer, the body positioned and the bolt tightened up through the epoxy resin; squeezing it between the cling film and the chassis - effectively making an insulated bed for the body to fit onto. The whole assembly was cooked under a couple of hot spot lights for an hour. The body was removed from the chassis well before the resin had completely cured and any excess trimmed way with a scalpel. The clear resin doesn’t show the seating very well, but it does give a nice solid fixing for the rear bolt. The wheel clearances are obviously fairly tight and so accurate fixing for the body is essential, if scale widths are to be maintained. I have worked out how the bodywork will be made: mainly as subassemblies, to ease the painting in NER livery, which was slightly more complex than the LNER style. That being so the smokebox saddle and boiler could be next or maybe the radial truck at the back. Just need to make my mind up… I must say how enjoyable it is to be making an engine from scratch again. I find the problem solving the best bit. Tim

My Skittle Alley is now up to full length. The running plate and valences is the trickiest part on these engines, here made of four pieces of brass silver soldered together. Details in the 2mm section, as ever. Tim

Sorry to be a bit repetitive but after a productive session today the running plate core is now complete for the Skittle Alley: now becoming an exceedingly long locomotive. The rear section was bent up and butted up to the middle. The hole in the stretcher is to take a locating pin when silver soldering. As before, the components were set up on the charcoal block and held in place with pins from drill shanks. In this photo the solder has just flashed: the flame and residual hot charcoal are visible. After cleaning up, but before removing the stretchers. These were removed with a fine diamond disc. Now set up on the engine. Whilst this part of the engine represents a good deal of work, it does give a solid foundation for the loco body. If it were etched, a sacrificial assembly jig would help in construction (as with Valour). If it were 3DP it would be simple to make. However, neither would be as strong as this solid brass assembly. The valence will be reduced in height by 0.2mm when I have a fresh pair of eyes. Tim

Work on the wavy, cascading, front running plate for the NER 4-6-2 class has been started. It is quite a challenge to keep such structures level and so the foundations are made from three pieces of 1.4mm thick brass silver soldered together: this will represent the valence on the edge of the running plate. Cutting in the concave form at the front of the running plate was achieved using an old steel finishing bur (they used to be used in dentistry) the surface irregularities were then tidied up with a fine round file. The components were set up a charcoal block ready for heating up, held in place with pins from broken drills. The solder paste can be seen in the middle joint - the other had been made previously. Powder borax flux is also added. The flame I use is a little gas torch - similar to the ones used to burn crème brûlées. Removed from the block and cleaned up. The rebate at the front of the concave forms will take the 5thou nickel silver running plate tops: these will have the fine details on them and, of course, the driving wheel splashers. The smoke box saddle will be bolted through at the front, not surprisingly, It will be a solid lump of brass. In fact, I suspect this engine will weigh in heavier than Mons Meg. Finishing with a bit of an arty shot with the running plate approximately held in place. There are sacrificial stiffening spacers that will be cut away once the back end is complete. Tim

Nah. A few more years left in that placeholder yet… Tim

That is very true, Tony. On CF it takes quite a while for a train to go round. Fortunately, we have the NLR and other lines to keep something happening for the viewer. Occasionally, the six mainlines get into a sort of sync when nothing happens for quite a while and then everything all at once: but that is apparently how the real thing sometimes appeared. Tim

I think it is a design that grows on you and has a certain elegance. I was intrigued enough to take a look at the Great Bear: the proportions of the cab and firebox don’t help with this engine, nor the tender. The rear radial truck is not a high point on either engine, but I wanted to have another 1920s loco in pre-group livery for CF which meant it had to be 2400. The Gresley Cartazzi arrangement was obviously much more sensible. All very subjective, though. Tim

Is it me, or does 10000 look like it’s cocking it’s back leg in this photo? Tim

At the same Nottingham show we were running a white mouse on Chiltern Green with red sparkly eyes. He was unfortunately never converted to fine scale. It also rained in the hall. The weather outside was very wet and so the punters came in soaked. Unfortunately, someone in the hall management forgot to turn on the roof/building ventilation system. Very rapidly, condensation formed on the iron beams and then dripped down on the layouts below. We had to arrange plastic sheets over the fiddle yard, whilst water actually ran down the Lea valley at Luton Hoo. Bizarre, but true. Tim

Yes, fully described in the 2mm section. Tim

Not sure of the answer to your question Tony but I’ve just popped up to the garret (2mm workshop) to take this photo: Posed next to 2mm scale royalty, namely the late, great, Denys Brownlee’s Scotsman. Tim P.S. I finish-turned a pair of Denys’ wheels for the rear radial truck a couple of days ago.

I don’t think so. This was June 1923 and they are recurved on the bottom corner. The buffer beams were cut back very much earlier in the year. It’s going to be fun making the three-step running plate but I have a cunning plan for that. Tim

Thanks Nick: I always love looking at photos of engines I model. The engine will actually be 2400 and in this condition: Nicely contemporaneous with Valour. The Dynamometer Car will follow (courtesy of Rapido Trains). The Phoenix Precision NER green is certainly pretty bright, maybe too vivid? It’s intriguing that with the short NER tender the overall length is the same as an A1, but with the Gresley tender they must have been rather awkward to handle on turntables. Tim

I suspect it was 1980, Chris. I recall having a conversation with Bob Essery at the front of the layout in Bristol where he proudly said everything on Heckmondwike was absolutely true to scale. ‘Including the white overhead lighting poles sticking out of the scenery and the fence posts not being up right?’, I asked. The layout did eventually perform well, but I also recall a wicked poster made by Dave Rowe at the previous Central Hall show where he described the ‘Monks of Heckmondwike Abbey summoned by bells’. He also did one for the ‘Chilling Green Monster’ at IMREX 1984: wish I’d kept it. For me, fine scale is all about the total scene, not just the track and wheels - although getting those right does help. Hope everyone has had a splendid day: I’ve had a day off from fairly solid modelling over the last couple of weeks. Just need to heat up the Christmas Pudding for tea. Here’s to a great New Year! Tim

I hoped I might get the Raven 4-6-2 class running before Christmas and I have! iPhones have a special microphone for picking up 2mm loco noise. It is currently running dry, which doesn’t help too much either. The drive arrangement is, as always, through a 10thou spring steel shaft with loops each end. It’s going to be an interesting engine to get round corners. All in all, I’m relieved it runs. Merry Christmas everyone! Tim