Ian_C's workbench - P4 and S7 allsorts

[adrian]

Again very impressive and certainly leading the way.

Although one small observation - on the MOK casting and the LG casting the waisting in on the lower part of the backhead seems to be markedly more pronounced than on your version. Is this because they are catering for the 7mm Finescale to fit between the limited back to back rather than Scale7?

 

[Ian_C]

Blimey, this is hard work. I put the backhead into the cab to check the fit, and then these two turn up...


In passing, who remembers Bissell, Bullhead and Bellcrank?

 

[Ian_C]

Again very impressive and certainly leading the way.

Although one small observation - on the MOK casting and the LG casting the waisting in on the lower part of the backhead seems to be markedly more pronounced than on your version. Is this because they are catering for the 7mm Finescale to fit between the limited back to back rather than Scale7?

Don't know Adrian. I've scratched my head a bit over this. Certainly the frames would be closer together , but there's no reason for the dummy frames inside the cab to be narrower than scale. Maybe on some models the actual frames project into the cab. Clearances around the reversing gear are very tight, so maybe it helps there. All I can say is that I've used the dimensions from drawings in the Wild Swan book. They translate into CAD with very little adjustment and that's the result. I do agree that there's a noticeable difference in the lower shape and comparing with the other castings, the outline shown on some of the other drawings, and with the photo on page 76. I do wonder if I have it 100% correct - but that's what the dimensions give you. In the end you don't see much of it in the finished model so If I've got it wrong somewhere I can live with it.

 

[Ian_C]

Got there in the end. I have to say that this has been the most challenging part of the build so far. I can't imagine that there's anything left that will be more demanding than this, so maybe I'll consider it all downhill from here!

Having made the new backhead as previously described the first learning was when I attempted to solder in some washout plugs made of brass wire. As originally machined it's a very big lump of brass and almost impossible to solder to. My 100W iron took a long time to bring the mass to a temperature where any solder would melt. The RSU wouldn't touch it at any setting that didn't blow holes in it. A micro blowtorch got it up to temperature easily enough to solder in the washout plugs, but hardly practical for adding any further detail. I understand now why the Laurie Griffin backhead casting was such a thin shell. So before any more detail was added the lump was set up on the milling machine again and a lot more brass was removed from the inside. Some areas where I didn't want to push my luck with the end mill were relieved with a burr in the mini drill. The average thickness was reduced to around 3mm. I didn't feel brave enough to go any further.


Even so it was still very difficult to solder details to this. The approach that worked best was to sub assemble chunks of detail on the bench using a 224C solder, tin the area on the backhead where it would be fixed with 145C solder and carefully sweat the parts on by heating the backhead to 145C or so with the 100W iron. At times it helped to wrap the part of the backhead that wasn't being worked on in kitchen roll to reduce the loss of heat to the air. The saving grace of this method was that with such a steep temperature gradient around the contact point of the iron it was possible , with care and close observation, to get the 145C solder to flow in a very small area without unsoldering details nearby. I also had some success by pre-heating the lump to a bit less than 145C with the big iron and then zapping on some detail with the RSU. Beware though, small brass castings don't like being heated directly with the RSU probe. If I do this again then I'll plan the backside machining in more detail and aim to have a shell of around 2mm thick.

So here's the result...


I have to say that it's not a 100% accurate rendition of the prototype. Many of the detail castings are not exactly the same as the prototype 8F shown in the pipe drawings and the works cab photo in the Wild Swan book. It does seem that although the steam fittings were standardised to a degree there were variations specific to particular classes. I used both the detail castings supplied with the MOK kit and some equivalent castings from the LG range. What's on the model is a mixture depending on: which casting best represented the prototype, how easy it was to modify a casting to suit and sometimes the quality of the individual castings. It went something like this...

• Firebox doors were straight from the MOK kit. I would have been nice to model them slightly open so that I could have a firebox LED behind, but that was going to be too much faff. The plates either side of the doors were made from brass shim with a few rivets pressed in.
• The steam manifold was also MOK, but modified by cutting off a bunch of plumbing on the RH side that must have been present on some Stanier classes but certainly wasn't on the 8F.
• The pipework was made from odds & sods of copper wire collected from electrical wiring over the years. It often wasn't possible to match the prototype diameters exactly so there's some approximation needed.
• Pipe unions were mostly made from small BA nuts drilled through to accept the wire.
• The regulator and gland were from the LG castings as the regulator handle most closely resembles the prototype in that it cranks out from the backhead very close to the gland.
• A blanking plate was made from scrap etch to cover the position where the sand gun valve was originally fitted, and subsequently removed, above the firebox doors.
• The control hand wheels on the manifold for the injector steam supply were from LG since they had the small handle projecting from the rim, whereas the MOK hand wheels did not.
• Nothing resembling the blowdown valve was included in either the MOK or the LG castings (although Ragstone Models does list one), so an approximation was made by butchering another unidentified cast thingumajig valve.
• Blower valve was the MOK casting.
• Sight gauges were from LG, although a bit fat and short compared with the prototype, but on the whole tidier castings than those from MOK (which were a bit too long and thin).
• The sanding valve was from LG. I missed of a couple of the small pipes from the sanding valve because they were too difficult to fit and you can't really see them anyway.
• The brake valves were a bit of a pain. As previously related 8142 was one of the locos fitted with both a combined steam and vacuum brake for which MOK provided a decent casting, and an independent steam brake valve to the left of it. So far as I can see nobody supplies a valve that looks like the independent steam brake valve, so that was improvised from the spare MOK sanding valve and joined to the combined valve. It's not perfect but a reasonable representation in approximately the right place. The two brake valves also make for more complicated plumbing as the steam supply pipes and the pipes to the steam brake cylinder have to be tee'd together. One tee was a simple plumbing type tee joint, the other was a funny looking forged fitting, more of a Y joint. Both had to be made from scratch.
• 8142 was fitted with a single cone ejector instead of the later and more common double cone type and the ejector steam valve was also different. Again I couldn't find a casting for this type of valve so the valve and it's mounting bracket was made from scratch. Incidentally the ejector valve hand wheel should also have a small projecting handle but since I only had 2 LG castings, which I used on the manifold, I fitted an MOK one here without the projecting handle. Not correct but I can live with it.
• The pressure and vacuum gauges were from the MOK supplied parts, the LG gauges being too large in diameter. There's nothing on the etch to represent the gauge mounting brackets so they were scaled from the Wild Swan book and made from scrap etch.

There's a lot of detail packed together on the back of the firebox and with some of the components not being quite to scale and an accumulation of tolerances it proved difficult to fit some details in exactly the right position. If you compare my rendition with the photo on page 76 of the Wild Swan book you'll spot the differences.

One last detail that's hardly visible is the lagging on the ejector steam pipes near the driver. On the prototype these pipes were wrapped with a cloth tape, maybe asbestos? I represented the lagging by wrapping the copper wire with a very thin ribbon of pewter foil. It's very soft and malleable stuff and can be made to conform closely to the wire beneath. Once artfully arranged the lagging was secured by a few drops of low viscosity cyano. I've had a little sheet of pewter foil for years, and I've finally found a use for it. It's something used in military modelling to make straps and webbing on figures. I assume you can still get the stuff.


P.S. I've just noticed that I've missed the small pipes from the bottom of the gauges.

 

[Ian_C]

Not much time to devote to modelling at the moment, but I did steal a couple of hours to clean and prime the backhead. Looks better in works grey I think.

 

[Ian_C]

I think the time is right to take a look at the upper works. The first challenge is to work out how all the DCC stuff is going to fit inside.

The firebox is largely occupied by the motor and gearbox so the DCC decoder and the speaker has to fit in the boiler and smokebox. I'm new to this DCC thing so it took a bit of research to figure out what I'd want to fit. I ended up with a Zimo MX696S decoder loaded with the Digitrains Zs003A Activedrive Stanier 2 cylinder sound profile, and the speaker(s) are twin Zimo sugarcubes in a bass reflex enclosure. There are so many speaker types available and so many different points of view regarding installation that I'm not 100% sure that this is the best solution. Fingers crossed that it'll work OK. Because I didn't want to be soldering directly to the decoder pins I've added the screw terminal connector board to the decoder. That makes it quite a big lump but it will fit in the boiler ...just...with some modification.

I puzzled a bit about how, if the speaker was installed in the boiler, any sound would escape to the outside world. The speaker went in the smoke box because there really wasn't anywhere else in the locomotive for it go. I didn't want to put the speaker in the tender because I wanted the noise to come from the prototype noisy end. There's a chimney hole that I can leave open, and I made a big hole in the bottom of the smokebox and some slots in the smokebox saddle. Hopefully enough whooshing and clanking will escape.



The speaker is quite long but slim enough to fit neatly down the centre of the smokebox. The DCC decoder would fit in the boiler in theory, but couldn't be inserted due the the boiler former rings at each end that shape and stiffen the boiler etch. The boiler former rings are plenty big enough to cope with some material removal to open up the hole. Marked out with callipers and the unwanted material easily removed with a carbide burr in a mini drill and tidied up with a file and emery.


As things stood the upper works were very rear heavy due to the cast firebox and the hefty brass backhead. The DCC decoder and the speakers don't weigh much at all. The challenge was to find enough space for ballast up front to balance the loco without getting in the way of the DCC decoder and speakers. The solution was to make some lead weights to fit in either side of the smokebox alongside the speaker but not blocking the passage of sound. To get the most weight in the space available and make a tidy job I decided to cast some lead weights to match the smokebox.

Simple enough ...
Make a mould from wood to match the internal diameter of the smokebox plus a few mm to machine off. A handy offcut of oak was used. Marked out and roughly plunge cut with an end mill to quickly remove most of the material...


Finished off in the lathe to the internal diameter of the smokebox, plus a few mm for cleaning up the weight...


Enough lead flashing was cut into small pieces to fill the mould with a bit to spare. The lead was melted in the bottom of an old WD spray can held in the vice and heated from below with a blowtorch. The dross was scooped off the top of the melt with an old teaspoon and the lead was poured steadily into the wooden mould. As you might expect there's a lot of smoke and bubbling as the wood chars, and the top sinks as the lead cools and contracts. IOSH Managing Safely head on for a minute here - it's dead easy to cast lead weights like this but some sensible precautions:

• Don't have any water or fluid anywhere near the molten lead and certainly not in the mould, a shower of molten lead isn't a 'good thing'
• I'd suggest decent gloves and eye protection are a minimum requirement
• Lead is toxic so don't breath in any dust or fumes from the handling or casting process - I worked near the wide open workshop door - and scrub hands afterwards. You might want to wear a suitable face mask if you can't work in open air.
• Carry out the work in an area where any spills of molten lead fall on a surface that can resist, such as concrete or tiles

Here's the cast lump after removal from the mould. No taper in the mould and a relatively rough surface, so it took some persuading to come out...


The cast lump was cleaned up to the smokebox diameter in the lathe. To say the lead was free cutting would be an understatement...


Slices were cut off the lump for the smokebox weights and another 'spare' to sit in the bottom of the boiler under the DCC decoder if I needed more weight to balance up. The slices were tidied up and the edges reduced with a file so that they would fit through the smokebox former rings...


And here's how they fit in the smoke box, leaving room for the speaker. They'll be epoxied in when the boiler assembly is complete and before the smokebox door is fitted.


The last job was to work out exactly how much weight was needed to balance the loco. No messing around with masses and moments and maths, all done empirically. The footplate was supported on a plank of balsa wood (negligible mass) and the upper works were placed in position on the footplate with the smokebox weights in situ. I wanted the loco to be evenly balanced about the centre of the driven wheelbase and that position was marked on the footplate. The whole caboodle was supported on some MDF blocks and a length of wire was placed under the balsa at the required centre of mass. Considering the mass of the firebox casting and the backhead I was surprised that the smokebox weights made it front heavy (but having them that far forward does help). The length of the smokebox weights was gradually reduced until the whole thing balanced on the wire.


For the record, the assembly shown above weighed 562g when it balanced. When added to the 'undressed' chassis the combined weight is 840g. When the cylinders and motion are added along with the remaining etched and cast parts on the boiler and cab I reckon it'll end up around 1,000g. Being new to 7mm I've no idea what the norm is, but that feels about right to me. It would be possible to add even more weight but I don't think it's needed.

 

[Brian McKenzie]

Very nicely presented, Ian. I'm wondering if the smokebox weights could have been left at their original length - to counteract weight of motor and gearbox when added at firebox end?
-Brian

 

[Ian@StEnochs]

I think the time is right to take a look at the upper works. The first challenge is to work out how all the DCC stuff is going to fit inside.
View attachment 92673
The firebox is largely occupied by the motor and gearbox so the DCC decoder and the speaker has to fit in the boiler and smokebox. I'm new to this DCC thing so it took a bit of research to figure out what I'd want to fit. I ended up with a Zimo MX696S decoder loaded with the Digitrains Zs003A Activedrive Stanier 2 cylinder sound profile, and the speaker(s) are twin Zimo sugarcubes in a bass reflex enclosure. There are so many speaker types available and so many different points of view regarding installation that I'm not 100% sure that this is the best solution. Fingers crossed that it'll work OK. Because I didn't want to be soldering directly to the decoder pins I've added the screw terminal connector board to the decoder. That makes it quite a big lump but it will fit in the boiler ...just...with some modification.

I puzzled a bit about how, if the speaker was installed in the boiler, any sound would escape to the outside world. The speaker went in the smoke box because there really wasn't anywhere else in the locomotive for it go. I didn't want to put the speaker in the tender because I wanted the noise to come from the prototype noisy end. There's a chimney hole that I can leave open, and I made a big hole in the bottom of the smokebox and some slots in the smokebox saddle. Hopefully enough whooshing and clanking will escape.
View attachment 92674


The speaker is quite long but slim enough to fit neatly down the centre of the smokebox. The DCC decoder would fit in the boiler in theory, but couldn't be inserted due the the boiler former rings at each end that shape and stiffen the boiler etch. The boiler former rings are plenty big enough to cope with some material removal to open up the hole. Marked out with callipers and the unwanted material easily removed with a carbide burr in a mini drill and tidied up with a file and emery.
View attachment 92675

As things stood the upper works were very rear heavy due to the cast firebox and the hefty brass backhead. The DCC decoder and the speakers don't weigh much at all. The challenge was to find enough space for ballast up front to balance the loco without getting in the way of the DCC decoder and speakers. The solution was to make some lead weights to fit in either side of the smokebox alongside the speaker but not blocking the passage of sound. To get the most weight in the space available and make a tidy job I decided to cast some lead weights to match the smokebox.

Simple enough ...
Make a mould from wood to match the internal diameter of the smokebox plus a few mm to machine off. A handy offcut of oak was used. Marked out and roughly plunge cut with an end mill to quickly remove most of the material...
View attachment 92676

Finished off in the lathe to the internal diameter of the smokebox, plus a few mm for cleaning up the weight...
View attachment 92677

Enough lead flashing was cut into small pieces to fill the mould with a bit to spare. The lead was melted in the bottom of an old WD spray can held in the vice and heated from below with a blowtorch. The dross was scooped off the top of the melt with an old teaspoon and the lead was poured steadily into the wooden mould. As you might expect there's a lot of smoke and bubbling as the wood chars, and the top sinks as the lead cools and contracts. IOSH Managing Safely head on for a minute here - it's dead easy to cast lead weights like this but some sensible precautions:

• Don't have any water or fluid anywhere near the molten lead and certainly not in the mould, a shower of molten lead isn't a 'good thing'
• I'd suggest decent gloves and eye protection are a minimum requirement
• Lead is toxic so don't breath in any dust or fumes from the handling or casting process - I worked near the wide open workshop door - and scrub hands afterwards. You might want to wear a suitable face mask if you can't work in open air.
• Carry out the work in an area where any spills of molten lead fall on a surface that can resist, such as concrete or tiles

View attachment 92678

Here's the cast lump after removal from the mould. No taper in the mould and a relatively rough surface, so it took some persuading to come out...
View attachment 92679

The cast lump was cleaned up to the smokebox diameter in the lathe. To say the lead was free cutting would be an understatement...
View attachment 92680

Slices were cut off the lump for the smokebox weights and another 'spare' to sit in the bottom of the boiler under the DCC decoder if I needed more weight to balance up. The slices were tidied up and the edges reduced with a file so that they would fit through the smokebox former rings...
View attachment 92681

And here's how they fit in the smoke box, leaving room for the speaker. They'll be epoxied in when the boiler assembly is complete and before the smokebox door is fitted.
View attachment 92682

The last job was to work out exactly how much weight was needed to balance the loco. No messing around with masses and moments and maths, all done empirically. The footplate was supported on a plank of balsa wood (negligible mass) and the upper works were placed in position on the footplate with the smokebox weights in situ. I wanted the loco to be evenly balanced about the centre of the driven wheelbase and that position was marked on the footplate. The whole caboodle was supported on some MDF blocks and a length of wire was placed under the balsa at the required centre of mass. Considering the mass of the firebox casting and the backhead I was surprised that the smokebox weights made it front heavy (but having them that far forward does help). The length of the smokebox weights was gradually reduced until the whole thing balanced on the wire.
View attachment 92683

For the record, the assembly shown above weighed 562g when it balanced. When added to the 'undressed' chassis the combined weight is 840g. When the cylinders and motion are added along with the remaining etched and cast parts on the boiler and cab I reckon it'll end up around 1,000g. Being new to 7mm I've no idea what the norm is, but that feels about right to me. It would be possible to add even more weight but I don't think it's needed.

Hi Ian,

I use a mould made from cardboard to cast lead in for weights. The card inner from toilet rolls is ideal. Just cut it longways, reduce to the required size and tape together with a turn of masking tape then close off one end with tape. I have an old tin tray on which the mould is placed to catch any spills and only heat the lead until it will pour. The card may char but I have never had one fail before the lead solidifys.

Ian.

 

[Ian_C]

Hi Ian,

I use a mould made from cardboard to cast lead in for weights.

Ian.

Cardboard! I'd never have bet money on that working! Thanks for the hint. Could save a bit of effort.

 

[Ian@StEnochs]

Cardboard! I'd never have bet money on that working! Thanks for the hint. Could save a bit of effort.

Another way is to make a simple open box with strips of wood nailed to a base, ideal for shaped blocks to fit in ash pans etc.

Ian.

 

[simond]

Or, if it’s all too difficult, the old lead shot idea works very well with casting resin, not PVA of course!

Of course, it’s nowhere near as dense as solid lead, (64% to 74% according to Wikipedia) but it’s a doddle to make a plasticine mould and cast to finished shape & size in that.

Best
Simon

 

[richard carr]

Ian

Why do you want to put the decoder in the loco ? why not in the tender, and why such a big expensive one when a MX644D would be perfectly adequate ?

Speakers in the smokebox is by the far best in my opinion but 1 speaker is usually better than 2 as unless they are perfectly in sync they interfere with one another.

Has that decoder go a built in stay alive ? If not don't forget to add one.

Richard

 

[Ian_C]

Why do you want to put the decoder in the loco ? why not in the tender, and why such a big expensive one when a MX644D would be perfectly adequate ?

Well Richard, as it turns out I don't want to put the decoder in the loco...because...

Although the whole thing fits neatly in the boiler I hadn't thought it through properly. I'd assumed that I could wriggle the speaker and decoder in and out of the boiler through the base of the firebox. The speaker was a fiddle but OK. The decoder is somewhat wider than the hole. Not a chance! Thought briefly about making the boiler and firebox as separable parts but couldn't see an easy way to do it. As you suggest, it does fit in the tender easily. And, yes there is a 'stay alive' capacitor and there's room for that in the tender too. Thanks for the advice though Richard - sometimes I just have to learn the hard way!

Praise be to the MOK tab and slot method ! It took less than 10 mins to cut the main tender parts out of the fret and slot them together to check the available space.

Why MX696? Cos' I don't know any better and I don't know how much current the motor will draw. MX644 is rated at 1.2A continuous. MX696 is 4A continuous, so comfortable overkill!

After that Homer Simpson episode a load of uncertainty around the boiler and footplate assembly has gone away so I thought I 'd press on with the front footplate. Making some progress again.

The curved front footplate sections were a pain to form up to match the valence, the half etched rivets didn't help when trying to bend it around a former. The brass buffer housings supplied by MOK are the cleanest brass castings I've ever come across - just about perfect. The holes in the bufferbeam needed opening out to 4mm to accept the spigots on the back of the buffer housings. Also added the small oil boxes on the outside of the frames. You can just see them on the frames above the main footplate before the frames and footplate drop down. Small pipes run down inside the frames and through the footplate to lubricate the pony truck. Early 8Fs had the oil boxes on the inside of the frames where apparently they were vulnerable to contamination from smokebox grot. By the time Crewe got around to 8142 they'd moved them outside the frames. I made some dents and dings in the front edge and corners of the foot plate - typical of late BR 8Fs. Starting to look less Churchward and more Stanier now don't you think?

 

[richard carr]

Ian

Thankfully it does fit in the tender.

As a rough guide to motor current draw, a coreless motor such as an RG7 or the Maxon that ABC offer, draw at most 600 milli amps, after that the motor tends to go pop so the MX644 will easily cope with that.
As for something a bit more traditional like a mashima 1833, they can draw upto an amp but, this is only when they are running at high speed, at low speeds they draw about 250 milli amps. Even Heljan diesels with their twin big can motors won't draw more than amp provided you keep the speed down, but run them flat out and you can see the current draw rise to 2.5 amps.


Richard

 

[Ian_C]

Ian

Thankfully it does fit in the tender.

As a rough guide to motor current draw, a coreless motor such as an RG7 or the Maxon that ABC offer, draw at most 600 milli amps, after that the motor tends to go pop so the MX644 will easily cope with that.
As for something a bit more traditional like a mashima 1833, they can draw upto an amp but, this is only when they are running at high speed, at low speeds they draw about 250 milli amps. Even Heljan diesels with their twin big can motors won't draw more than amp provided you keep the speed down, but run them flat out and you can see the current draw rise to 2.5 amps.


Richard

OK, thanks for that. I feel as if I've learned something today!

 

[Ian_C]

Since we tend to look on our models from above most of the time I think the boiler fittings can be a bit of a signature detail, and worth some effort. What came with the kit was a rather nice chimney in cast brass, a very average top feed casing in cast brass and a rather ugly lump of white metal which I assume must be the dome.

The chimney casting measures up about 0.5mm short compared with the Wild Swan drawings. But it's a nice casting and looks the part so I'll use it.

The top feed cover casting isn't great, and anyway, by 1965 48142 was wearing the the later cover with the clacks closer to the centre of the boiler and a little 'top hat' cover on the top. The drawings in the Wild Swan book are one thing and what's revealed in decent photos are a slightly different thing. There seems to be some variation in the shape of the centre part of the cover where it flares out to fit the boiler cladding,. Some seem to have a little raised section to clear the valve fixing studs and nuts, other seem not to have that, they blend more or less smoothly down to the fitting flange. I've opted for the latter, simply because it's easier to model and I really can't tell which sub-species of cover 48142 had. Makes a top feed nerd of you this sort of exercise!

The dome. No amount of filing and sculpting is going to resurrect that pewter pebble. Need something better. No variation in dome covers, they all look the same to me, although some are more battered than others and even on the prototype some fit better than others.

Surprisingly I've not been able to find alternative castings for a dome or a later type top feed casing. I've looked in the usual places and catalogues without success. If you know of a source then I'd be interested.

Having had some success with 3D printed parts before I thought I'd have a go at a dome and top feed. Modelling them in CAD turned out to be a fair challenge (for me anyway). Sections of the drawings in the Wild Swan book were scanned and enlarged to scale off. Also there's a Roche drawing for a Stanier dome cover that contributed some information. Lots of bookmarked photos as well, including some taken looking down on the loco which give you more of a clue. But blimey, it was hard going, with loads of curved surfaces and splines and having to construct some difficult geometry to make it work. In the end there's a certain amount of approximation and judgement required to model up something that looks right. A full day of virtual modelling later and this is the result..




...and assembled onto a virtual boiler...

...even better if I could work out how to apply 'filthy BR grey' as a material finish before doing the rendering in CAD, but 'automotive grey paint' will have to do.

There are some adjustments for the limitations of the 3D printing process. The sheet metal edge thickness is increased to about the minimum I think the process can deal with. There's also the option to manually thin those flanges down a bit before fitting to the boiler. There will be some layering pattern visible on the printed parts. I think that'll be more noticeable on the dome so I've not added the fixing bolts to the flange in order to make sanding and finishing easier. Instead I've put holes in the right places so I can add the screw heads afterwards. Next job is to prepare some .stl files and send them off to CW Railways to quote.

 

[Ian_C]

There's some detail missing from the etched boiler and it's all quite noticeable, so the part of the brain that's responsible for these things tells me that I must add it.

There are some extra washout plug locations on all of the 8F boilers and they show up as circular recesses in the boiler cladding. For the sloping throat plate boilers, of which this is one, there are four plugs. Two forward near the smokebox and two just in front of the firebox. At the bottom of the recess is a taper plug, similar to those on the sides of the firebox. The plug fits in the boiler proper and the recess in the cladding is quite deep so it's rarely visible in photos, but it seemed silly to make a hole with nothing in it so some plugs were made too. Having worked out the locations from the Wild Swan book they were marked on the boiler with the lightest of scribe marks and drilled out to 2.6mm. Four recesses were turned from brass bar and the plugs made from 1.2mm wire with the end squared off. There's a small spigot on the top of the turnings to help locate them in the boiler holes as they are soldered in place from inside.


Definitely a job to do before the boiler is assembled to the smokebox and firebox. The front recesses are easy enough.




The rear recesses were more of a challenge since Stanier's drawing office clearly didn't give any thought to how these locomotives would be modelled in the 21st century. The rear plugs are very close to the firebox and in the usual not thinking things through style the turned recesses sit directly where the boiler former ring is located. A reinforcing piece was soldered into the boiler before the former ring was cut away to clear the turned parts.


Likewise the spigot on the front of the firebox casting had to be relieved in two places to allow the boiler to fit properly again.


A couple more things to add at this stage. There are some small circular inspection/access covers on the top of the cladding just forward of the top feed. These were made from brass shim (foil almost): solder some scraps of shim to the end of a piece of brass rod, turn the lot down to the required diameter, drill four holes in the end on the milling machine, unsolder and separate the shims. Added to the boiler with a zap from the RSU. Some cheating though - I left the holes in the shims rather than trying to add tiny screw heads. The brain sees four things where it expects to see four things and it's not immediately obvious there are no screw heads protruding. The boiler cladding is made in two halves that meet at the top and bottom of the boiler, where they overlap. That was represented by scribing a deep line just offset from the centre line where the left sheet overlaps the right.

 

[Ian_C]

Time to take another big step forward, the assembly of the smokebox, boiler and firebox to the footplate. I've never had the confidence to solder to white metal so the firebox was fixed to the footplate and cab front with epoxy. Araldite Rapid gives enough time to position and clamp things and forms a durable bond in my experience. Odds of success increased by roughening the joint faces slightly and cleaning with IPA before applying the epoxy. Smokebox soldered to boiler after taking a lot of care to align them accurately. The boiler / smokebox assembly was fixed to the rest by soldering the smokebox to the saddle and epoxy between boiler and firebox.

Steam pipes next. I've always thought that the steam pipes are one of the signature items on Stanier front ends. They suggest to me a kind of elbows out sleeves rolled up ready to do business look. In the MOK kit the steam pipes, well actually the steam pipe covers because that'a what you see, are supplied as brass castings. Quite cleverly no attempt has been made to match length and profile at the ends of the casting to the smokebox and footplate surfaces, because that would be be really difficult to get right and vulnerable to assembly tolerances. Rather ,the casting projects through the apertures etched in the smokebox and footplate and at the joints are covered with etched overlays to represent the riveted flange. Makes a potentially difficult job quite easy. The castings do project slightly into the smokebox so there will need to be a small relief made in the lead smokebox weights made previously. What the steam pipe castings lack is the rivet detail at the edges of the cover. Easily added by drilling 0.5mm holes in the right paces, soldering in 0.5mm brass wire and filing down to leave a representation of the rivets.



The chimney casting was fitted to the smokebox next. I elected to remove the cast spigot that was meant to locate the chimney because it makes it easier to fettle the curved surface to fit the smokebox, and it enabled me to open up the chimney bore to the full diameter to improve the amount of DCC noise that can escape. It took very little fettling to get the chimney sat down on the smokebox nicely, but it took a very long time to be sure the chimney was positioned properly. I ended up tacking the chimney in place, taking a photo from directly in front and using that to judge if the chimney was truly vertical (but you do have to be aware of the distortion imparted by the lens depending on how the subject is framed). I find it much easier to spot wonky things on a photo than in real life 3D eyeball.

Upper assembly dropped onto chassis and LH cylinder just to see how things look. Can't resist these little previews of the finished article, keeps me motivated. Very much showing the Stanier style now


Forgive the connecting rod resting on the floor, and I wonder if the front footstep is a little off vertical? And isn't there an oil box missing from the top of the connecting rod? Add it to the list...

 

[Ian_C]

Sandbox fillers. One of those simple jobs that turned out to be not so simple.

The rear filler that is accessed through a hole in the footplate alongside the firebox turned out to have the hole in the wrong place. Awkwardly it was about half a hole out, so a brass plug was turned to fill the hole, soldered in position from the underside of the footplate and a new hole was made in the correct position. The filler was soldered in place, now correctly aligned with the rear sandbox which is fixed to the chassis. You don't actually see the filler pipe since it's hidden beneath the footplate, but the rear sandbox is the only one that can really be seen since it's outside the chassis plate and it just looks a bit goofy when the corresponding sandbox filler doesn't align with it.

This is about he point that the instructions wave goodbye - "The remainder of the body parts and castings may now be added and detailed to taste." There's a lot of detail left to add from photos and drawings and a few parts left in the kit, some identifiable, some not.

The sandbox filler castings and the etched parts for the shields are obvious enough. I fitted them but they didn't look convincing, even with the edges thinned a bit..


They're etched in 0.46mm N/S and that scales to about 20mm thick in 7mm, so they look a bit lumpy. Also they lack the rivet and bolt detail where the shield halves join, and they're missing the top flange that rests against the boiler cladding. Spent a whole morning fretting about it before deciding to remove them and make some replacements. There made from 0.2mm brass (about 8mm thick at 7mm scale - so probably still a little thick). Mark out, cut out, drill, rivet and fold. Takes a little time but easy enough. Scratch building really.


The end result is an improvement I think.

 

[Ian_C]

The sandbox filler shields were not so easily laid to rest! Having pondered them a bit it seems that I'd got the rear ones too close to vertical. They appear to be more inclined in decent photos, but not so steeply inclined as the ones up front. Made then a bit too tall. So they had to come off and be replaced by some more, slightly shorter ones, that lean in and contact the boiler at the right angle. I'm very efficient at making these parts now!

The MOK kit has some parts for both straight and curved reversing rods. 8142, being one of the earlier locos, was fitted with the curved variety. Both of the etched rods lack the 'funny shaped bit' that projects from the lower edge of the rod to contact the rod support bracket roller. The drawings in the Wild Swan book clearly show the 'funny shaped bit' to be a separate plate applied to the outside surface of the rod. In photos of both types of rod the 'funny shaped bit' appears flush with the surface of the rod. I followed the photos and added a bit of scrap etch to the rod and filed it to the funny shape. The kit has a decent representation of the cover for the straight rod where it passes through the footplate, but there's nothing for the curved rod. The cover for the curved rod is a bit enigmatic as it's hardly seen in any photos. There's definitely a small cover of some sort but I couldn't figure it out from any photos. The answer was eventually found on the C31482 frame arrangement drawing in the Wild Swan book. It was scaled off the drawing and modelled roughly on CAD to get a sense of the thing.

A cover was made from 0.2mm brass, riveted in the appropriate locations, and a small brass lump filed to shape and added on top. The slot was cut in the cover for the reversing rod before it was fitted to the footplate. A couple of etched rivets needed to be flattened on the foot plate where the cover sits. Small amount of cheating - the rod itself doesn't project through the footplate, it just terminates in the cover slot. That's another small bit done.