Rebuilt Bullied Light Pacific.
Rebuilt Bullied West Country/Battle of Britain Class 4-6-2.
The original Tri-ang Merchant Navy (MN) on the left whilst on the right is the Lincoln Loco's moulding fitted to the MN chassis
The finished 'Exeter' as now running on David Garner's layout
Introduction
The Tri-ang TT 'Merchant Navy' (MN) loco uses a chassis dimensionally more akin to the smaller West Country (WC) class pacific. As far more of these (and the identical 'Battle of Britain' class) were built, it has been an aim of mine to modify the MN body to represent the smaller loco. Exeter Central requires several examples of both classes, in original and rebuilt forms. My as yet unproven suspicion is that modifying the Tri-ang MN body moulding is one way to obtain a West Country in original condition, so the more complicated Rebuilt form would be a commercial offering. Following a conversation with Lenny Seeny, he offered to make an 'Applegreen' resin moulding for the Rebuilt Bullied West Country/Battle of Britain class 4-6-2 to fit the Tri-ang Merchant Navy chassis. This section describes the construction of models from Lenny's early mouldings. Please note, later versions have been updated so may require a slightly different approach.
1. Tri-ang Merchant Navy chassis with shortened front
The first task was the fitting of the body to the Tri-ang chassis. The chassis does need shortening at the front by removing a wedge shaped piece, 3 mm on top and 2 mm on bottom. This can be done by wrapping the chassis in kitchen paper and masking tape to prevent filings getting into the motor and bearings and then using a file or junior hacksaw to shorten the chassis block (see photo 1).
My initial attempt cut the front too short so I had to superglue a plasticard 'wedge' into the body to locate the chassis correctly. (Photo 2)
2. Locating wedge
Fitting the Chassis to the body
3. Body moulding as delivered
As delivered, the body (photo 3) came sprayed in grey primer which does a good job of smoothing off the 'grain' caused by the 3d printed masters. Unfortunately in a few areas such as the front frames, smoke box door and firebox top, this graining was still apparent so I rubbed it down using 1200 grit wet and dry paper. The firebox has had to be made slightly taller to accommodate the motor but this is hardly noticeable but it does leave the cab roof higher than the tender so I filed down and re-profiled the cab roof losing about 1 mm in height to improved the side view.
4. Body cut out template (1mm plasticard)
This initial body moulding needs to be modified to fit the chassis. This is done with the use of a Template (see photo 4.) made from 60th Plasticard to the dimensions shown opposite. The vertical web underneath the body's cab floor has to have a 9 mm section cut from the center into which the 9 x 3 tab is located (see photo 5). With the template laid centrally, it is marked round using a pencil. (see photos 6 & 7)
5. (Top) Cab underfloor. 6. (bottom) template in place.
7. Body marked for milling
As this body was one of the early mouldings the wheel cutouts under the footplate are in the wrong places. With the body marked from the template using a pencil, new wheel cutouts were made, as were recesses for the valve gear. The cutting was done with a steel rotary burr in a mini-drill (see photo 8) and the cutouts made 1.5 mm deep until the template sat in the cutouts, flush with the underside of the footplate. The next job was to widen inside the body from 9.5 mm to 12 mm the motor and brush holder (see photo 9). It was slightly too narrow for the mechanism about the boiler skirt which was filed all along, but particularly at the rear until the motor could be dropped in at the rear and slid forward until the cut down front of the chassis met the body behind the smoke box. In this position the front driving axle should be 41 mm from the buffer beam.
8. Milling Out is fairly easy with a steel burr in a rotary mini-drill.
9. Body filed out at inside rear so the motor drops in and slides forward with the brush holder inside the boiler, above the skirt
10. Slide bar cut out
11. Here is the much larger cutout for the slide bar brackets. Essentially the boiler skirts need widening to match the full internal width of the smoke box behind the deflector plates. Some breaking through behind the lubricators and sandboxes is inevitable but not a problem.
12. Footplate height 19 mm above table top
Once the main milling is complete the body and chassis can be tried for fit. It may require further small tweaks with the mill and/or files to get the body sitting square on the chassis. When sat on it's flanges, the bottom of the locomotive foot plate should be around 19 mm above base level (see photo 12).
The next job was to fasten the body to the chassis. I fashioned a housing from 1 mm plasticard, superglued under the cab to accommodate the lug on the rear of the chassis (photos 13,14). I next drilled through the moulding under the smoke box and marked through into the chassis with a 1.5 mm drill bit. This chassis marking was then drilled 1.1 mm and tapped 12 BA for a depth of 5 mm to take a 10 mm screw (photos 15,16)
13. Rear chassis lug housing #1 - 1mm thick, 24 mm x 4 mm with a slot cut 7.5 mm x 1.6 mm
14. Rear chassis lug housing #2 Glued with cyano to the rear of the under cab web
15. Body drilled, chassis tapped. Body hole countersunk.
16. Body secured with screw.
After assembly, the loco was attached to a tender, placed on the layout and a test run made from Exeter Junction shed to pick up the Plymouth train from platform 2....all seemed to run OK so I knew that nothing was catching.
Passing the carriage shed on the down through line
Being coupled to the train for Plymouth.
Body Detailing.
Not much is required here. The cab roof was thinned down, re-profiled to match the Tri-ang tender and a 0.25mm hatch added. A reversing shaft was fitted by drilling through the footplate and cab front and fitting a piece of 0.8mm wire. A further refinement was to add sandbox fillers made from plasticard with 1mm rod pushed into holes drilled centrally. The rear ones having to be cut shorter as there is a skirt fitted under the boiler at this point to hide the chassis. The cab windows seemed a little small so I filed them out larger towards the front and top. The last item to add was the injectors under the cab. In the absence of any drawing or close up photo, I bodged this by glueing a piece of plastic under the cab and adding bits of plastic rod and offcuts to replicate what I thought the injectors looked like. A couple of pieces of copper wire completed the ensemble.
The Ejector pipe on the left hand side was 0.75 mm plastic rod superglued in position and positioned by using another template (see above), also marked for drilling the boiler and deflectors for handrail knobs.
Valve Gear
The loco is now at the running stage but I also wanted to improve the valve gear. The rebuilt Locomotives were fitted with Walschaerts valve gear and for this, I had some parts from the Tri-ang Britannia Loco (T.97), specifically the Return cranks (ST.5136), eccentric rods (ST.5135) and radius rod/Expansion Link (XT.107/8). As I only had enough for one loco and they are no longer available as spares, I will have to find other solutions for the other bodies.
The easier solution for this loco is to replace the MN slide bar assemblies with the Britannia slide bar castings (XT.105/6). Unfortunately these have a different shaped slide bar to the Rebuilt West Country's so I decided to keep the correct ones and proceeded as follows.
Firstly the valve gear assemblies, XT.107 & 8 were modified by cutting off 2 mm from the top of the support and bending outwards through 90 deg the first 2 mm which normally slots into the Britannia slide bar casting (see photo 17). Next the casting was removed and a small hole 0.8 mm in diameter was drilled through from the back of the upright, just on top of the 'cylinder' and elongated to 1 mm (see photo 18 ). The valve gear assemblies were then threaded through the slide bars and the bent part located in the holes. This establishes the position of the spigot for the valve gear support bracket.
17. Modified valve gear assembly
18. Hole drilled from back and assembly fitted
Support Bracket
The Valve gear support bracket top was made from 1 mm plasticard and the side plates from 0.75 mm. The top and side plates were assembled first and fitted to the loco. The top and bottom support and hole plate were cut from 1 mm as shown below, and assembled with plenty of solvent for a really strong job but not yet glued to the side plates. The pictures show what it should look like when assembled.
Parts for Bracket and supports
The top support has the bottom support glued under it to leave a recess to take the hole plate. This is well glued in and a small off cut is fitted at 90 deg between the hole plate and bottom support to re-enforce it.
The hole is made by drilling 0.8mm and elongating it to be a tight fit on the spigot at the rear of the valve gear assembly.
Spigot in support bracket showing re-enforcement off cut
Spigot through hole plate and assembly supported on its side
Support shown glued to side plates
Bracket and assembly sitting in recess under footplate
The bracket is fitted and held by the suppressor securing screw. I then fitted the body with the valve gear assemblies in place. The supports were then pressed onto the valve gear spigots, held against the underside of the footplate and positioned against the side plates between the drivers. A brush full of solvent was then flooded onto the side plate join and held for a few minutes until set. This accurately positioned the supports on the side frames which was left to harden overnight.
To complete the valve gear I had to find a way of securing the return crank to the center crank pin as the MN has no provision for this and the crank pin on the Britannia is a quite different design. The solution was as follows. Remove the existing crank pin (ST.4019) and the spacer (ST.4022) and open up the holes in the coupling and connecting rods to 1.6 mm. Take a 5 mm x 12 BA screw and file 2 flats on the thread equally on both sides so the screw is approx 0.8 mm wide and the return crank slides on but doesn't rotate. Take a piece of 1.6 mm O/D brass tube and open the hole up with firstly a 1.1 mm drill bit followed by a 1.2 mm drill bit...easy on a lathe but do-able by hand. Trim it to make 2 parts 2.5 mm long. Make a replacement for the spacer by filing down the outside of a 10 BA washer to 3 mm diameter to match the coupling rod boss.
The assembly of this lot can be a bit fiddly but proceed thus..First place the return crank on the screw up to the head..ensure it cranks away from the wheel face. Replace the coupling rod, inset the brass tube followed by the spacing washer, then the connecting rod and fit the screw to hold it all together. When tightened with the crank pin at the 6 'O' clock position the return crank should be pointing at the 2 'O' clock position. If its 180 deg away you can turn the crank round on the screw. If it's a small amount out, a few stokes with a file to shorten the tube will allow you to alter the cranks position...I said it's fiddly but a little trial and error will do it. I found the tubes came out at 2.3 mm long in the end when the screw was done up tightly. To add to the fiddle, you have to finish off by fitting the Eccentric rod and I found some juggling between the crank and Valve gear assembly was required as well as bending the connecting rods to clear the slide bars and eccentric when running.
Cylinders
These are made from plasticard and slide forward to clip onto the slide bar bracket and hold the new valve gear in place at the same time. The Drawing shows the parts to be cut out and how they are glued to form the clip on cover. I found it easier to glue the parts together on the assembled loco so the rear cylinder cover can be positioned accurately up against the running plate and covering the slide bar bracket.
Cylinder rear
Showing arrangement of parts. Cylinder front is shown down on the table, cover to left.
Cylinder top view
Showing rear cover to left, then Spacer then Back plate
Cylinder in position
To fit, remove body and slide onto front of slide bar bracket,
Tender
There are two main types of tender on these locos 4500 gallon and 5500 gallon. As I was basing this model on a drawing from the Railway Modeller which showed a 4500 gallon tender, this is what I built by modifying the Tri-ang Merchant Navy tender. The first task was to fit PTFE bearings to the wheels as per my standard procedure (see Tri-ang Wheel bearings on Rolling stock page). A piece of 0.5 x 2.5 x 3.5 mm rectangle of plasticard was attached with impact adhesive to represent the Axlebox cover.
The body was removed by sliding it off of the chassis, the rear moulded steps and lighting conduit were pared off and cleaned up. The tender was then marked for cutting down at the rear, including shortening the coal space. The bunker rear was marked 28 mm from the back and cut vertically down to a horizontal line 13.5 mm from the tender bottom. This removed everything above the tank top. A new rear bunker was added from 0.5 mm plastic cut to approx. 26.5 mm x 10 mm and shaped to match the tender cab. When dry, the moulded coal was shortened and reshaped to fit into the new bunker. Behind the bunker a new tender top was made from 26.5 mm x 28.5 mm x 1.0 mm plastic and glued in place. A slight overhang allows sanding back to size.
The top was finished with a set of air tanks made from 4mm plastic tube and a new tank filler made from the same. To fit an end to the tube I glued the end to piece of 0.25 mm plastic and when dry, trimmed the end to shape with a knife and filed it round to match the tube. Four sealed tubes, 8 mm long were glued together, mounted on a 0.5 mm plate to raise them off of the tank top and glued centrally behind the bunker rear. When dry they were dressed flat ready to be fitted with brass wire to represent the air pipes.
The filler was a 1.5mm length of tube, sealed and adorned with a small piece of microstrip to represent the lid handle.
In order to make the curved protection plate over the air tanks, I made a mould from brass as shown in the photo (left). A female part was milled out to shape and a male part filed to fit. In operation a 10mm wide piece of 0.25 mm plastic was clamped between the two halves and the whole lot placed in the oven at 120oC for 6 minutes. Upon removal the mould was run under the cold tap until cool and when the clamp was released I had a correctly moulded air tank cover. I made it over size to fit a variety of applications and it is easy enough to cut down to size. In this case it was reduced in height to approximately 5 mm and shortened by cutting a piece out of the middle and rejoining the two ends. Later a touch of plastic filler hid the join.
This view shows the tender before the fitting of the rear steps. It also shows how I had to add a piece to the bunker back, to match the shape of the tender cab as I initially cut it too short...duh!
The loco drawbar was shortened by 5mm by bending the wire and cutting off the surplus. I fitted a short piece of PTFE tube over the wire to give a tighter fit into the tender drawbar hole. This stops the tender jiggling about behind the loco when moving.
The rear ladders are made from 0.4mm Nickel silver wire soldered together and bent to shape. A piece of MDF was coloured black with a marker pen and the outline of the ladders marked on. Then 0.5mm holes were drilled just inside each intersection such that when the wires are inserted they but together ready for soldering. The 3 steps are formed 6mm lengths around the ends of small pliars into staple shapes, approx 2.5mm wide. They are inserted into the holes in the MDF, a long (33mm) and a short (20mm) length are laid along side. Each join is fluxed with dilute phosphoric acid and a wipe with a tinned iron unites the steps and rails.
The tender back is marked with a pencil to show the position of the outer (longest) ladder rail. This is 8mm from the side of the central lamp position. A 0.5mm hole is drilled through the tender back, on this line but just above the bottom of the tender body so the ladders bottom rails can be inserted. The legs on the top and bottom steps are trimmed back and the ladders cleaned up of excess solder. The middle legs are filed to just under 2mm long to act as spacers and keep the ladder the correct distance from the tender rear. They also serve to prevent the ladder being bent during handling. The bottom of the rails are bent through 90 deg, 3.5mm below the bottom step and cut to approximately 3mm long. The ladder is then positioned and the other bottom hole marked for drilling.
Once positioned and checked for vertical, the top hole on the inner side of the ladder is marked and drilled. The inner side rail is then bent to fit and cut long enough to be inserted. This positions the ladder ready to shape the handrail on the outer side.
An 'L' shaped piece of styrene, 5.5mm x 4mm x width of the tender is placed on top of the tank and the handrail bent to shape over it. A hole is drilled in the tank top to accomodate the handrail. The ladder is lowered into place, handrail into the top hole first and then the other three prongs are inserted before a little 'Judicious tweaking' ensures a correct fit.
The ladders are removed for painting and will be re- fitted prior to varnishing. As the lighting conduit on the rear of the tender had been removed with the moulded steps, it was replaced with 0.25mm plastic rod. (just visible on the two pictures above).
The glazing was cut from clear PVC and the wooden frame painted on with a bow pen. It was carefully trimmed by trial and error until it just fitted into the window opening before being secured with 'Glue and Glaze' after varnishing.
The handrails were cut to length from 15thou piano wire, inserted into 3mm Society handrail knobs and fitted into the pre-drilled holes before being attached with superglue
17 Squadron ready for the paint shop
Painting and finishing
All four models were primed with Halfords grey primer and airbrushed with Railmatch BR Loco Green. Tamiya tape was used to mask before Humbrol satin black was sprayed onto smokebox, cylinders and cab and tender tops. Once dry, the lining was carried out using Modelmasters 2mm scale BR loco lining. The running plate edges were lined in Humbrol orange using a bow pen as the decal sheet doesn't contain anything suitable. This lining doesn't stick very well to sating paint and afew bits had to be glued on with clear gum.
The smokebox number plate and nameplate were drawn on the PC using Libreoffice 'Draw' and printed at high definition onto photo paper by colour laser. The number plate was stuck directly onto the smokebox door whilst the nameplate was mounted onto a suitably shaped piece of 0.5mm styrene and glued with superglue onto the footplate. David had supplied a set of etched plates for 'Exeter' so these were cut out and stuck to the nameplate instead of printing the name.
Exeter crest
17 Squadron crest
Tavistock crest
Torrington crest
After a thorough drying and a careful brush to remove dust, two coats of Precision satin varnish were applied by airbrush. Following that the glazing, ladders and handrails were fixed before a tender was loaded with real coal, crushed to an appropriate size
The first body finished as 34001 - Exeter with 5500g tender
