CLASS 171 Build

How to do it, advice sought and offered.
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Joined: Mon Aug 13, 2012 8:43 pm

CLASS 171 Build

Post by lindsay_g » Wed Jan 16, 2019 7:33 pm

As threatened in [url=http]another thread[/url], I’m going to document the build of a Class 171 from the John Boyle etch which will become available from David Elvy of Alba Models. This might help those that would purchase such an etch or those already in possession of etches. This initial post is setting the scene, build will start later.

First thing to say is that it is not a kit but an etch for the body only presently, all other parts and fittings have to be sourced or homemade in order to complete the build. That might sound daunting but it won’t turn out nearly as bad as it sounds.
Here is an image of the etch with all parts listed :
171 etch and part description.jpg
171 etch and part description.jpg (144.57 KiB) Viewed 17811 times
As you can see, there are sides for both engines of the SN orders with the shorter bunker and rear toolbox and those of the 2 later orders with the longer bunker. The etch seems to be well scaled with the dimensions of the main parts that I’ve measured so far pretty well spot on - parts will be tested for scale as we proceed. However, some parts on the etch are very delicate, and some parts, non-essential thankfully such as the smokebox door embellishment, too fine to survive the etching process (well, they were on my etch at least). I suspected things started off as a 7mm etch reduced to 4mm but without adjustments being made, but Dave Lochrie has said recently that it was designed for 4mm. I still think it will go together well to make a lovely little model – time will tell!

There are several brass sheet items missing from the etch (they’re listed above), most noticeably the boiler, but these can be cut to size fairly quickly. The chassis does not form part of the etch but build of this will also be described.


Let’s ensure everyone has a good idea of what is being modelled. Below is an image of a Class 171 (No 223, one of the later batches) :
Courtesy of CRA
223.jpg (90.03 KiB) Viewed 17998 times
It’s a lovely little engine and the quirkiness of the solid bogie wheels and Drummond dome add interest. There is little to be seen beneath the boiler as that area is pretty well obscured by the side tanks and front splashers, so this should allow the motor and gearbox to be fitted in a number of ways in line with individuals’ preferences.

The main reference points for my build are a GA kindly provided by Mike Williams and images from our Association (I will try to remember to credit CRA with any images used, but if I forget I hope these words credit the source). A slight distortion in dimensions has occurred sometime during copying/photographing of the GA but there are more than enough dimensions on the GA to accurately scale the model. Images of 171’s are not plentiful and there are few providing good coverage of the front and rear ends. 40 years of Caledonian Locomotives also has useful info plus a drawing of the backplate/cross-section looking forward

There were slight difference between the engines of the various batches, and further differences introduced whilst in the service of the CR or LMS. I’ll highlight those that I’ve noticed (CR period only) as build proceeds – everyone else can chip in for other differences I don’t notice. I’ll be modelling the longer bunker version, electing to go for No 193, so that I can maximise space for weight and a DCC chip. According to Marshall’s Balerno Line book, No 193 did run over that line and Barnton. I don’t have any back-up information to that claim so if anyone out there has more info that would be just dandy. In fact if anyone has any images of 193 other than the 2 side-on images that appear in many publications, I’d love to see them. Whilst I’m at it, there is a third appeal, might anyone have any information on any full bunker 171’s that were allocated to Dalry Road?

I managed to pick up a bag containing a part-started model, remaining untouched parts on the etch, chassis sides, and bogies wheels. I’m still well pleased to have secured this, but the ease of build has been somewhat compromised as a result of the parts that had been built. So my build will differ slightly from the way I’d build it starting from a pristine etch. I’ll try and take this into account as build progresses.

For this build, as far as possible I’m going to use or list items available on the market and the website addresses will be provided. I may work around some available items but will explain how such parts can be used. To date, I’ve sourced or have feelers out for most parts needed. The main body parts that I haven’t tracked down so far are the tank fillers and the square cylinder lubricators fitted initially. Here are close ups of both :
Lubricators & Fillers.jpg
Courtesy of CRA
Lubricators & Fillers.jpg (29.19 KiB) Viewed 17998 times
The other main part that isn’t commercially available is the coupling driving rods. This gap in the market isn’t restricted to Class 171’s. There are virtually no 4mm CR rods available on the market and those that come with some kits are pretty inaccurate and/or made from inappropriate material. Most if not all 6 coupled rods are rigid or are hinged on the middle wheel rather than on the knuckle just rear of that wheel. I’ll probably put out another post regarding coupling rods.

If anyone is aware of the availability of any of these missing items, myself and anyone else interested in this build would be pleased to hear from you.

My experience from reading progress on build by others, or my more limited experience of reporting on my own builds, is that there needs to be a few days between each update to allow others to access the posts, take them in, and respond/question - not everyone accesses a forum daily or has time to respond immediately. If one update quickly follows another, resultant responses on different aspects can all get a bit confusing. So, I’ll try and keep the posts flowing but not at breakneck speed.

Well, that sets the scene. The next instalment will see build will commence.

Last edited by lindsay_g on Tue Jan 22, 2019 12:02 am, edited 1 time in total.

jim mac
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Joined: Mon Aug 13, 2012 7:20 pm

Re: CLASS 171 Build

Post by jim mac » Thu Jan 17, 2019 10:18 am

I don't have any information n Dalry Road allocated locomotives, but have attached the three images I have of CR193.
044T CR193 (Perth).jpg
044T CR193 (Perth).jpg (189.52 KiB) Viewed 17969 times
044T CR193 (unk location).jpg
044T CR193 (unk location).jpg (238.87 KiB) Viewed 17969 times
044T CR193.jpg
044T CR193.jpg (207.87 KiB) Viewed 17969 times
jim mac

Posts: 380
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Re: CLASS 171 Build

Post by lindsay_g » Thu Jan 17, 2019 10:48 am

Perhaps this thread should have a sub-title of Spot the Difference. I haven't seen the middle image previously but notice immediately that there is a rear sand pipe. This isn't present in the other 2, although a sand box can be seen within the cab of the top image. Intriguing.


David Elvy
Posts: 440
Joined: Tue Aug 21, 2012 6:26 am

Re: CLASS 171 Build

Post by David Elvy » Thu Jan 17, 2019 8:19 pm

7mm scale chassis etch. I know they are not quite correct but I have a few etches for a H Class which are bellied and I'll be modifying for my chassis.
171 Chassis Etch resize.JPG
171 Chassis Etch resize.JPG (46.92 KiB) Viewed 17931 times

Posts: 380
Joined: Mon Aug 13, 2012 8:43 pm

CLASS 171 Build - Footplate and Below

Post by lindsay_g » Tue Jan 22, 2019 1:08 am

As I’ve already said this is a body etch only – there are no fittings or chassis parts (not presently at least). There are also no instructions. All parts on the etch seem to be identifiable, but as build progresses we might have to review that. We’ll also have to figure out how all parts go together but that might be self-evident. The starting point for most kit or scratch builds is the assembly of the footplate, buffer beams, and valances or the chassis. I’m starting with the former. Examination of these parts before build reveals :

The footplate is accurate in length and width and needs little attention, but dependent on how you want to build things. Apologies, forgot to take image but you can see the areas referred to in the complete footplate near the end.

The footplate would only have been around ⅜” thick so the etch is way overscale – not something unique to this etch - invariably the footplate and beams are on the same etched sheet yet the latter can be 3-4 times thicker on the prototype. Only the side edges above the valances show on this loco so the width of these edges can be feathered down by filing/sanding to represent near-scale thickness, best done before valances are attached.

I want to add as much weight as possible plus at least a DCC chip and stay-alive capacitor(s), so I opened out the footplate under the bunker area to allow access from below. This adds to the delicacy of the footplate but no more than the tank/front splasher areas. Only a rough cut is made, the footplate can be filed back further in this area once the cab and bunker items are soldered in place. There is a cross section of brass just rear of the front splashers which might be seen when built but it is as well retaining it in place until the superstructure is soldered in place.

Since an accompanying chassis formed no part of the etch design, there is no provision for securing the body to a chassis. The rear of the chassis was a possible area but I’ve opened that out for access. There isn’t sufficient brass to the front for soldering on a nut so I soldered on a laminated section just rear of the valve chest under the smokebox area onto which an 8BA nut will be soldered (with the chassis in place). The rear of the chassis will be secured by a tongue and groove arrangement.

At this stage it’s also better to open out the location holes for the sand fillers on the front splashers to around .5-1mm at least before folds commence. No holes are etched for the cab grab handles which were outward of the cab sides. These were marked out and drilled before build commenced as it would be harder to achieve once the cab is soldered in place.

The valances are very delicate and, despite me saying earlier that the sizings on the etch were good, these don’t have enough width. Whilst there is no exact measurement on the GA, they appear to be around 4½”deep deduced from both the GA and images. By comparison, the etched valances are only 1mm wide. Despite this, I may have been tempted to use the etched parts as they’re a pain to fettle, except one of mine was missing and the other was in a bit of a sorry state having been part soldered previously to the footplate so I resolved to make new ones of the correct width. If using the etched parts, notice that they are part etched on the inner face for the position of the cab steps, so bear this in mind before soldering. This area is very very delicate – my solitary valance showed this half-etched area on the non-etched side. Perhaps adding the rear of the steps at this early stage would be no bad idea to avoid such kinking – they could then be de-soldered once the valances are in place to avoid damage to them. The relative widths and the fragility can be seen (somewhat) in the image below :
Valance comparison.jpg
Valance comparison.jpg (36.27 KiB) Viewed 17813 times
I’ll get a bit anal again! Although I can’t make out the exact thickness from the GA, the beams were around 1¼” thick – a scale .42mm – but the etch is only .3mm thick. So, you can leave them undersized, sweat on another layer, or replace with thicker material. I went for the last as it is neater than sweating on another layer then filing the new area back – it’s also one less lamination to possibly come adrift later. An original was used as a template, scribed around and the parts cut/files to shape. The holes for the buffers and drawhooks were also drilled out (but see below re the drawhook holes). The height of the footplate on these engines was quite low and the frame depth shallow such that the beams extended above the footplate around the buffers so the footplate and beams are more or less a flush fit – there is no footplate overhang to speak off in 4mm. However the footplate does overhang the valances at the sides but by a mere .5mm.

I’d normally assemble the beams, valances, and footplate on a sheet of glass to ensure the footplate is perfectly level, but the buffer surrounds prohibit this – that and the fact that the splashers on mine had been folded up and I didn’t want them coming adrift by flattening them out again. So I cut an MDF block with a hole to accommodate the folded areas as well as the buffer surround areas. These 5 parts were then be soldered together. Thereafter, the front splashers can be folded up and the top areas added to both the inner and outer splasher areas. One sentence makes that all sound easy – the outer rod splasher side/tops are a real faff to unite as, to a lesser extent, is the upper surfaces of the main splasher. I’m not quite sure why the splasher top etch had a section that already exists on the footplate etch (where the sand filler will go), so it was removed. I also don’t know why there were 2 separate splasher sides on the etch.

FINAL FOOTPLATE BITS (at this stage)
I then added a couple of items that require a fair amount of heat. The sprung Drummond buffers came from Alan Gibson Workshop, and because of that low beam the inner bush had to be filed down to fit beneath the footplate :
Buffers.jpg (86.67 KiB) Viewed 17813 times
The drawhooks and drawhook plates came from Ambis Engineering. Note that the etched hole for the drawhook in the beams is incorrectly placed – it should be towards the top of the beam as the footplate and beam are set lower than normal. Not all 171’s had drawhook plates (there are few images where the drawhook is clearly visible). I decided to add them per a couple of individual examples, one of which was 193's sister engine (although they may have been in-service additions) - they also covered the wrongly positioned holes! :
192 front and 175 rear.jpg
Image shows front buffer of No 192 and rear of No 175
192 front and 175 rear.jpg (18.44 KiB) Viewed 17813 times
I’m also adding these at this early stage as the rear one needs to be in place before the chassis securing point can be fashioned. So to date, the footplate assembly now looks like this :
Footplate complete.jpg
Footplate complete.jpg (43.82 KiB) Viewed 17813 times
Not a huge amount covered but I'm having problems with uploading presently. Next up, in the near future, will be the cab and bunker area.


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CLASS 171 Build - Cab & Bunker

Post by lindsay_g » Thu Jan 24, 2019 12:50 am

Now we’re going to start making these bits of brass look more like a loco by adding some superstructure.

Cab/Bunker parts
The bunker rear, cab rear and cab front are all sized to be soldered to the inside of the cab sides. All but the bunker rear have other parts to be soldered to them and it’s possibly easier to get these positioned correctly before assembling the parts on the footplate. I do hope so, as that‘s the way I’ve decided to go on this occasion. Here are the 5 parts as assembled individually :
Cab  and Bunker Parts.jpg
Cab and Bunker Parts.jpg (89.25 KiB) Viewed 17710 times
The cruel magnification of the image shows up a few wee probs that will have to be corrected and will be mentioned in the comments of each part. This just reinforces the argument that everything should be photographed and inspected to improve our modelling!

Cab Front
There’s no hole etched for the whistle control rod so that’s better drilled before we go any further. This should be dead centre and 1mm above the half etched boiler line. However, I’ve put that side to the inside of the cab as a guide for the backplate as I have other ideas in mind for positioning the boiler The window spectacles were then soldered into place. I chose the best 2 out of 4 on the etch but I see from the image that I still need to even them up further.

Holes were drilled for lamps to be glued into place once the engine is eventually painted and lined (one lamp is temporarily in place in the image). The lower half of the lamp brackets were then represented by using part of the lamp irons on the etch. There is a half etched area for placing the lamp brackets but it is too low and needs to be filled with solder or Milliput later on (one etched area can be seen in the image).

There is no etched parts for the beading around the side look-outs which also holds the upper part of the cab handles. The Caley in their wisdom made things difficult for modellers as the handles were set around 2½” out from the cab sides with the beading curving outwards on both sides. For each side a length of spare etch material was bent to fit snuggly within the aperture on the cab side. It was made from an over-wide length of etch material so that holes could be drilled for the handles then the remainder filed back once it was soldered in place. I’ve yet to file the thickness of the beading back as it’s too heavy presently. Below is a comparison of the GA and my modelled interpretation :
Beading at handles2.jpg
Beading at handles2.jpg (13.26 KiB) Viewed 17710 times
Cab Rear
There is a half etched line for creating a 90 degree bend then it has to be curved to shape above that bend. There is an area on the etch which provided a template for the bend. Be warned that it is a pain to get the tight curve formed – at least it was with mine but I suspect that the brass of my etch was harder than normal. The heavy soldering on the cab rear is because the 90 degree bend was being affected during the curving process. The rear barred spectacles (nice items on the etch – but a tad delicate ) were fitted (but I see I’ll need to straighten one marginally). I have no idea how the rear windows of No 193 were fitted out in service. There were 4 spectacle arrangements that I’ve come across :
Rear Spectacles2.jpg
Rear Spectacles2.jpg (31.43 KiB) Viewed 17709 times
Clockwise from top left they are : Without protection - not many seen in this format; "Porthole" design - several of the duplicate numbered locos had this format; Barred - probably second most common; format only seen on loco 175.

Bunker Rear
At this stage, the upper edge only needs to be curved to the outline of the cab sides but that turned out to be problematic as there is a half etched slot for a lamp-iron which distorts quite readily when curving commences – it will have to be made good with solder or Milliput in due course. The addition of the lamp iron is better left until last minute stuff. There is also beading along the top rear of the bunker on the GA which will be added later

Bunker Top
There is no top plate for the bunker for the coal to sit on top of so this was cut from waste material – just a simple rectangle to be fitted 1 or 2mm below bunker top level. No great time was expended on cutting the rectangle nor on how level it was fitted - it won't be seen when the coal is added!

Cab/Bunker Build
The 5 main parts can be assembled in various ways. I elected to solder the front and one side together ensuring they are exactly aligned (bottoms and tops in line; overlapped edge level with the other edge; at right angles) then similarly added the second side with the bunker rear temporarily in place to ensure everything was square. This was then fitted centrally between the footplate sides with the rear of the bunker against the buffer beam. The 2 remaining parts were then soldered in place. Sounds straightforward - needless to say it wasn't. The beading on the rear of the bunker was then added - 6mm wire soldered on then filed down to shape. Finally, careful filing around all these bits that were added and then removal of excess solder.

Suddenly it’s now taking on the look of an engine :
cab on.jpg
cab on.jpg (36.17 KiB) Viewed 17710 times
Next up it will be the boiler and side tanks.


Alan K
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Re: CLASS 171 Build

Post by Alan K » Thu Jan 24, 2019 8:41 pm

Looking great already Lindsay! I'm a little alarmed that there hasn't been any response/ encouraging remarks from anyone so far....!
I can't quite remember how I soldered the beading round the lookout when I did the 0-4-2ST, but I used 0.1mm strip, and might have used a little wooden block with rounded corners to force the beading into the 'corners' for soldering. I couldn't get the beading to form the crank, so had to make the cranked parts separately and hide the joint with solder.
I decided that the spectacle plates I made were too thick (when you see the photos, they are very slim and delicate) and filed them thinner and polished with wet and dry and a wooden block after soldering.
I agree whole-heartedly about inspecting the photographs. I think it's all too easy for us to make automatic corrections to how we see things - for some reason the photo shows it as it is, warts and all! That's my experience anyway.


David Elvy
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Re: CLASS 171 Build

Post by David Elvy » Fri Jan 25, 2019 6:44 am


Inspiration indeed to crack on with mine, thanks for the commentary, it’s going to be a shame to paint once it’s comple.


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Re: CLASS 171 Build

Post by lindsay_g » Fri Jan 25, 2019 11:52 am

Hi Alan, and thanks for your comments.

Spectacles are another victim of the thickness of etch material and really need to be thinned down. Invariably they are etched too wide as well. Perhaps spectacles half etched and to scale width would be too delicate. The barred rear spectacles had the rims half etched but the bars untouched – not so fragile and they do give the impression of the bars having been added.

As you say, reducing the thickness of the spectacles is easier done once they’re soldered in place. It’s also easier to reduce the width by increasing the inside diameter once they’re soldered in place. Like you I use wet and dry for reducing the thickness and a host of other things. I use double sides selotape to attach them to a variety of bases, and you can’t get too many shapes and sizes either! :
WandD.jpg (160.56 KiB) Viewed 17608 times
The Garryflex is good for final rubbing and polishing as well, and can be cut into smaller pieces for nooks and crannies.


Posts: 380
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Re: CLASS 171 Build

Post by lindsay_g » Sat Jan 26, 2019 6:37 pm

Boiler and Tanks

Boiler and Overlays
The boiler doesn’t form part of the etch so I made mine from brass sheet which was then rolled to shape. However, an alternative is brass tube as, rather conveniently, the diameter of the boiler is 16mm and such tube is available and comes in 500mm lengths. I’m pleased to say David Elvy will supply a length of tube with the etch. As such I’ll not go into the sizes and everything connected with brass sheet being converted to a boiler unless anyone is particularly interested. Because of the small diameter it taxed the rolling bars and needed to be held in place for soldering, here it is with some of the instruments of torture employed :

boiler.jpg (47.42 KiB) Viewed 17542 times
Whatever method is employed, the boiler needs to be marked out and drilled for the chimney, dome, and whistle at distances of 4.5mm, 37mm, and 52mm from the front edge of the boiler. There should then be 2 overlays added to represent the stepped finish at the smokebox. The first should measure 9.7mm wide and the second 9.2mm wide. (Only one layer is supplied on the etch and that has a half etched area for a lamp iron, measures 8.7 wide with the chimney hole drilled centrally). Both of these need to be drilled for the chimney.
The first layer should be soldered all the way around the boiler, the second about as far as the splasher top when it then curves back outwards and finishes horizontal. As far as I can make out there shouldn’t be any daylight between the rear of the splasher top and the smokebox – but some may be more enlightened. Whatever, the final shape can’t be finalised until the smokebox front is soldered in place and both parts offered up to the footplate assembly. To assist this soldering, the parts can be bolted together via a 10BA (or similar) through the chimney holes.
Holes can then be drilled for the clack valves which are midway up the boiler and 15mm in from the front of the boiler. The final handrail knob holes and hole for the blower valve can’t be drilled until the boiler and tanks are soldered in place.

Smokebox Front
This part is sized well and looks a well-shaped item. However, it has been half etched with a raised border around most of the outside – good images show that there was no raised area. It may be that the person designing the etch mistook the burnished area as a raised area (I too was in doubt until a better supply of images show it just wasn’t the case). Or perhaps it is prominent so that paint can be sanded off to emulate the burnished area – however the raised edge around the smokebox wrapper is only half the width of the edge down the splasher edge. So, all in all I’m at a loss to explain why it was etched as such.
This part might be used in reverse but I’m a bit wary of its fragility so I fashioned a new piece – easily achieved by just tracing around the original, then a few minutes with a piercing saw and files. I also marked the centre of the smokebox door from the kit etch and drilled it 1mm so that the 2 parts could be aligned when filing and for centering the smokebox door (see below).
Holes for handrails and injectors in the smokebox front : These are more easily drilled, or re-drilled, before the item is soldered in place. The ones that are etched are incorrectly placed. The knob holes are marginally high, the lubricator holes c1.5mm too high. The lubricators are not shown in the GA and only the height of the handrail knobs can be determined from it. However, the following image will help locate them, alongside the parts in question with some calculation lines in evidence :

Smokebox front.jpg
Smokebox front.jpg (35.93 KiB) Viewed 17540 times
I cut a disc (13.3mm) on adhesive label via the Silhouette cutter to represent the smokebox door and centred it on the smokebox front to help locate everything. The centre of the lubricators are more or less in line with the bottom of the smokebox door, and the handrail knobs are 16.4mm above the footplate. The width apart of both is down to judgement – I just related them to the smokebox door and curved steam chest cover and to one another (the space between the knobs is narrower than between the injectors).

Cab Angle Iron (aka Rear Height Gauge)
An angle iron ran around the boiler and tank tops attaching them to the cab (it can be seen in the image a few paragraphs down). It’s quite prominent so worth modelling but not so easy to achieve in L shape format. I’m going to model it in 2 parts, the second part will be soldered around the boiler and tank top when fitted. The first part will be well oversized initially and soldered to the rear of the boiler and also act as a height gauge for the rear of the boiler

Boiler Sub-assembly
The boiler and smokebox front were soldered up initially, then the Cab Angle Iron Plate soldered at the rear. Sounds simple but getting the drilled holes ending up bang at the top and both ends and resulting in the correct height (19mm to top of boiler – remember the smokebox will be higher) at both ends is fun. However, with a boiler assembly that can be trial fitted on and off the footplate assembly will make final assembly easy as well as interim judgements for motor and gearbox positioning as we’ll see later. When these are all soldered together the rear plate can be file down to the correct height and the smokebox front filed flush with the wrapper.

Tank Sides
The tank sides turn out to be c1mm too short to fit over the front and rear etch sections. Length suggests sides fit within ends but the etched holes in the footplate suggest otherwise. I found this out after bending one to shape – I should have checked the fit on the chassis and size from the GA before bending as bending these etch pieces like the cab rear was really difficult. Having found the bend in the cab rear hard to make I scribed a number of lines to make curving easier, but it didn't really help. They’re ony a simple rectangle, so new pieces were cut and shaped.
There were 8 rivets visible on the vertical surfaces of the tank sides – bang in the middle of the lining – that’s the Caley being helpful to the modeller again – thanks a heap! These have been half etched on the parts so need to be punched out before or after the corner bend is made. They don’t have any holes for the filler caps but the position of these can’t easily be determined until the tank sides are bent to shape. 2 handrail knobs were fitted to the top of the tank (you can see them in the image below). They are positioned immediately behind the filler (and in line with the dome), and 6mm from the rear of the tank.

Tank Front
The tank front etches seem to be OK size wise. There were 2 rivets holding the front in place that haven’t been half etched. They’re under 1mm in from the inner edge and above the level of those in the tank sides :

Rivets and handrail knobs.jpg
Rivets and handrail knobs.jpg (40.51 KiB) Viewed 17540 times
Tank Sub-assembly
The sides and fronts can then be soldered together ready for trial fit on the footplate :

Boiler and tanks.jpg
Boiler and tanks.jpg (47.53 KiB) Viewed 17540 times
And yet again it’s looking more like a 171 :
Boiler and tanks in place.jpg
Boiler and tanks in place.jpg (48.69 KiB) Viewed 17540 times
Before these can be soldered in place we’ll need to butcher the boiler to house the motor and gearbox. That requires a chassis in place, so that’s what we’re moving onto next time round.

Last edited by lindsay_g on Sat Jan 26, 2019 8:49 pm, edited 2 times in total.

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Re: CLASS 171 Build

Post by jimwatt2mm » Sat Jan 26, 2019 8:13 pm

Not meaning to be critical, Lindsay, but on a matter of terminology, these are not injectors on the smokebox front, but lubricators and the curved plate at the bottom gives access to the cylinders and valves.

Jim W (in pedantic mode!)

Posts: 380
Joined: Mon Aug 13, 2012 8:43 pm

Re: CLASS 171 Build

Post by lindsay_g » Sat Jan 26, 2019 8:52 pm

Cheers Jim and no offence taken.

When I was writing it, I though injectors was the wrong term and meant to check it out but forgot - probably got distracted with all the probs of uploading. Now corrected.


Alan K
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Joined: Mon Aug 13, 2012 9:41 pm

Re: CLASS 171 Build

Post by Alan K » Sun Jan 27, 2019 9:06 am

The injectors are all too visible between the rear driver and bogie wheels I'm afraid! An 'interesting' challenge to come...


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Joined: Mon Aug 20, 2012 5:40 pm

Re: CLASS 171 Build

Post by jasp » Sun Jan 27, 2019 9:25 am

lindsay_g wrote:
Thu Jan 17, 2019 10:48 am
Perhaps this thread should have a sub-title of Spot the Difference. I haven't seen the middle image previously but notice immediately that there is a rear sand pipe. This isn't present in the other 2, although a sand box can be seen within the cab of the top image. Intriguing.

I wonder why you would have a sand pipe for a bogie wheel rather than a driver
Jim P

Posts: 380
Joined: Mon Aug 13, 2012 8:43 pm

CLASS 171 Build - Chassis Part 1

Post by lindsay_g » Tue Feb 05, 2019 12:56 am


(This update is in 3 parts in view of the maximum images per post and breaking it up logically)

My bag of parts came with chassis and bogie frames. They’re of unknown origin but look like Alan Gibson Workshop items to me (confirmed by Dave Lochrie). They looked good initially but unfortunately, and possibly, because of the beams/footplate configuration the chassis sides are actually c2mm too short. The vertical black lines in the image below are the front and rear extremities, the driving wheel centre points and the bogie pivot. Most of that shortfall is between the rear driving wheel and bogie, as can be seen from the following image with the Gibson frames being the lower items :

Chassis sides.jpg
Chassis sides.jpg (49.97 KiB) Viewed 17068 times
Various possibilities are being looked at to make a chassis available, but at present the Gibson frames are the only one available. So, I had a choice to make :
- live with the shortfall
- cut and shunt between rear driver and bogie – lots more metal has to come out of there for the ash pan as well. Not a great idea on a chassis frame in any case.
- replace the chassis frames.
I didn’t fancy the first 2 options, so – as you probably guessed from the image above – I elected to make chassis frames from scratch. These were cut from nickel silver sheet using a template created in a Silhouette cutter and printed on label sheet :

Chassis template.jpg
Chassis template.jpg (51.4 KiB) Viewed 17068 times

Suspension or Rigid Chassis?

Everyone is going to have their preference for rigid/compensated/sprung arrangements - I’m not going to comment on each. I’m using my favoured option of Continuous Springy Beams (CSB’s) for the drivers and a not dissimilar arrangement for the bogie. For those not familiar with CSB’s, lots of information can be found on the relevant pages on the CLAG website – at first sight the maths/physics might seem daunting but it’s actually pretty straightforward once you get into it which doesn’t take days.
Holes were drilled for the spring fulcrums (WD handrail knobs from Markits – sorry no link as their catalogue isn’t on line presently) which were soldered in place. Hornblocks from High Level Kits were then soldered into place. Spacersaver hornblocks were fitted for the rear wheels to leave room for the gearbox to be fitted. Next up, spacers were added. I’ve spent some time trying to get these placed so that I don’t have to resite them for later work such as pick-ups and so on. However, per usual, I will probably have to move some. The front spacer will secure the chassis to the body with a screw through it into a nut soldered on the body. The middle spacer will act as a backstop for the CSB wire (which has to be free moving – the buffer beam will act as the front stop when the chassis is fitted to the body). The spacer between the bogie wheels will act as a running plate for the bogie. And the rear spacer will be a fitting point for the Westinghouse reservoir - the chassis will be secured to the body by a tongue and groove arrangement at the rear (the groove can be seen in the image a few paragraphs further on).

Wheels, Motor & Gearbox
The driving wheels are 5’ diameter. Mine came from Alan Gibson Workshop. The Gearbox is a Roadrunner+ with 54:1 gearing and the motor a Mashima 1020 again from High Level Kits. Put together we then have :

Drivers and Motor on.jpg
Drivers and Motor on.jpg (52.23 KiB) Viewed 17068 times
Last edited by lindsay_g on Tue Feb 05, 2019 1:58 am, edited 5 times in total.

Posts: 380
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CLASS 171 Build - Chassis Part 2

Post by lindsay_g » Tue Feb 05, 2019 1:05 am


We have a wee problem with bogie wheels. These were solid 2’ 6” but they aren’t available anywhere as far as I’m aware (David Elvy also had problems with 7mm wheels). I inherited a pair of Sharman wheels with my bag of bits but these are no longer manufactured. However, Alan Gibson Workshop do 2’ 7½“ Lowmac wheels which, at only .5mm out, would do most folks - including me if I were needing a set of these wheels. Here’s a comparison of the 2 side by side.

Bogie Wheels.jpg
Bogie Wheels.jpg (30.18 KiB) Viewed 17067 times
The Sharman wheels are slightly undersized so the difference from the prototype diameter looks more extreme than it actually is. There would be just a small bit of work involved in filling the holes in the Gibson wheels

Bogie Frame
There are a host of views on how bogies should be set up, whether rigid, sprung, compensated, allowing for side play, and so on. I’m not going to start any debate on which is best for which gauge so I’ll leave everyone to follow their favoured path. Mine is the sprung route (with sideplay restraint added later), again along the same principle as the CSB’s, with a sprung beam each side within an inner and outer frame, the outer frame being the frame from the Alan Gibson chassis with 2 fulcrums for the spring and the inner beam scratchbuilt with one fulcrum. Hope these images help describe what I’m saying :

Bogie.jpg (27.19 KiB) Viewed 17067 times
The Sharman wheels that I got with the etch didn’t come without extra work, the Lowmac wheels could have been fitted easier! They come with an overlength axle that is c2.4mm diameter, which isn’t a recognised size (normally ⅛” or 2mm) so I drilled 2mm bushes out to 2.3mm before finishing with a broach.
Last edited by lindsay_g on Tue Feb 05, 2019 1:32 am, edited 1 time in total.

Posts: 380
Joined: Mon Aug 13, 2012 8:43 pm

CLASS 171 Build - Chassis Part 3

Post by lindsay_g » Tue Feb 05, 2019 1:23 am


The bogie will have sideplay via a swinging arm, the engine end of which will sit on a plate between parts representing the firebox so this will have to be built and fitted, at least temporarily. The firebox and ashpan assembly is made up of 5 layers :

Firebox.jpg (38.16 KiB) Viewed 17068 times
Again the Silhouette cutter software was used to create the templates which were then attached to N/S sheet (some still attached in the image above), cut, and fettled. The row of rivets was achieved by taping that part to a Bill Bedford handrail jig (shown left in the image - it’s versatility has no bounds!) and tapping a slightly blunted needle with a toffee hammer through a row of holes.
The 5 parts were soldered together using a resistance soldering iron (although edge soldering would do) using a 1mm brass wire as a location point (seen to the right of the image) which will eventually be filed into a square representing a drain (?) plug. If you represent that plug, there are 3 different chassis cut outs that I’ve come across (2 on the same engine at differing parts of its lifetime), so get it right for your model :

Plugs on 223 1223 and 193.jpg
All images are courtesy of the CRA.
Plugs on 223 1223 and 193.jpg (12.95 KiB) Viewed 17068 times
In case the differences aren't immediately discernible, the frame on the left has an intact hole cut into it (earlier 223), the middle image shows that circular hole being truncated at the lower edge (223 later renumbered as 1223) and the right image has a semi-circular topped hole but with the lower sides going straight down.
With both sides soldered up and then temporarily soldered in place via the brass wire, the height of the plate for the swinging arm was assessed (nothing scientific – that’s beyond me) and tack soldered in place until the height was assured (it's not critical, the swinging arm could be cranked). The swinging arm was positioned and holes drilled through both the plate and the swinging arm and a 10BA nut and bolt fitted temporarily.

With the driving wheels and motor/gearbox assembly, and bogie added, it seems that we now have the rudiments of a chassis :

Chassis1.jpg (48.56 KiB) Viewed 17068 times
Chassis2.jpg (46.39 KiB) Viewed 17068 times
Chassis3.jpg (46.92 KiB) Viewed 17068 times
I’m going to leave adding the detailing of the chassis and pick-up arrangements until later. Next time round I’m turning attention back to detailing of the superstructure.


P.S. Yes, before anyone comments, the driving wheels are not sitting square to the chassis. Doesn't make me happy! First one partially attached with the axle in the vertical drill post and the second via a GW quartering jig with appropriate shims in place, so not so sure how this could have happened. Further work needed there or replacements required!

Alan K
Posts: 339
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Re: CLASS 171 Build

Post by Alan K » Wed Feb 06, 2019 8:15 pm

Great stuff Lindsay. I think you made the right choice to make new frames. I think that many of the Alan Gibson frames were commissions presumably with dimensions supplied, which don't always match up to the 'proper' drawing. I didn't even have that for the Killin Pug as there isn't one, but I didn't look carefully enough at the Alan Gibson frames beforehand and didn't realise (until much later) that the cutouts for the hornblocks weren't deep enough! As a consequence I had to shorten compensating beams in order to get the ride height sorted, which was a real pain.
Having successfully 'converted' one of my 264 Class pugs to split frame, I would have been tempted to use PCB spacers and make the 171 split frame. Just think - no pickups to worry about!! But like you I think the CSB suspension is the way to go, and wish that I had used them for my 262.
I'll be watching future progress with interest.
But I hadn't realised how multi-talented you were - all this and confectionary too (well why would you have a toffee hammer in your toolkit....!)


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Joined: Mon Aug 13, 2012 8:43 pm

Re: CLASS 171 Build - Fitting Boiler & Tanks

Post by lindsay_g » Fri Feb 08, 2019 11:20 am

Butchering the boiler
I’d already marked out a possible cut area on the boiler (you can see it as a hatched area in an image in a previous post). This was well within the tank area to avoid any cock ups. Before cutting, I was wary of the boiler brass springing outwards (remember it was too small a radius for the rolling bars) so I quickly created a couple of formers to solder on to it and hold the remaining part in place. It was then cut using a cutting disc in a Dremel. The “height gauge” at the rear allowed me to test fit and keep on increasing the cut area until the gearbox and motor were sitting square within the tank/boiler area. Here’s how things are looking :

Boiler and motor fit.jpg
Boiler and motor fit.jpg (44.78 KiB) Viewed 16869 times
For the meantime, I’m leaving the boiler with that minimum clearance but will cut that back further once in place. However, the gearbox may be a tight-ish fit so I filed that back to more or less match the profile of the motor.I then test fitted the tanks. On the positive side, the truncated end of the boiler cannot be seen when they are in place. A small area of the gears and gear box can just be seen - if you get up close enough - but they can be disguised further in due course. On the negative side – I’ve realised from studying images that the angle bracket between cab and boiler didn’t just go around the boiler but extended onto the tank tops and because of its L shape and the bends involved, it flowed in a curve from the boiler to the tank tops. Ah!! So off came half of the rear plate to be replaced by a flowing half of the rear angle iron :

Butchered boiler and new rear plate..jpg
Butchered boiler and new rear plate..jpg (35.64 KiB) Viewed 16869 times
With that completed, it was time to attach the boiler and tanks to the footplate. Before starting this, it was as well to check the footplate is still straight and square. It was always a fragile item and has undergone some manhandling. It did indeed require some minor tweaks before progressing - if this step is missed, you might well have a twisted superstructure since it is pretty well rigid after the boiler and tanks are soldered into place. Before committing to solder, 2 other things were addressed :
- I removed the cross brass member to the rear of the splashers, and
- I drilled a couple of holes in the rear of the left hand water tank for the water depth gauge which I’d just noticed some evidence of in a few images. It’s the same as was on 429’s and 782’s (and possibly others) - here’s an image of said handle on 419 :

Depth gauge.jpg
Depth gauge.jpg (55.08 KiB) Viewed 16869 times
With that out of the way, it was ready to solder everything in place, care being taken to align everything correctly and squarely, adding each piece but only tack soldering until correct positioning was assured. Thereafter we can go wild with solder and flux around all the joins. As far as possible, all this soldering is done from behind and beneath as it involves a lot less removal of excess solder. With the boiler and tanks soldered together, the temporary formers could be removed. Here‘s the superstructure after a lot of solder removal, filing, W&D, and fibreglass brushing. Still not perfect – a lot more solder will be applied as detail is added :

boiler and tanks soldered.jpg
boiler and tanks soldered.jpg (46.71 KiB) Viewed 16869 times
Still some further solder to be applied to fill missing areas. 2 location slots for the side tanks certainly need attention. However, after admiring progress as a stimulant to future activity, it will be time to get going with detailing in the next instalment.


David Elvy
Posts: 440
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Re: CLASS 171 Build

Post by David Elvy » Fri Feb 08, 2019 1:24 pm


I predominantly use smaller motors similar to the type 4mm models use in the larger engines, does this scale down to allow 4mm modellers to use the larger 2mm scale motor and gearbox arrangements, just a thought.


Alan K
Posts: 339
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Re: CLASS 171 Build

Post by Alan K » Fri Feb 08, 2019 8:01 pm

Are you planning on a restraint for stopping the motor from clouting the inside of the boiler when activated? It shouldn't be rigidly fixed to the frame with a sprung suspension. There's a reference to this somwhere in the CLAG article. I found that having a wire hooked in an oversized hole gave enough slop to cope.


Posts: 380
Joined: Mon Aug 13, 2012 8:43 pm

Re: CLASS 171 Build

Post by lindsay_g » Tue Feb 12, 2019 11:29 am

Apologies for the delay in replying.

I predominantly use smaller motors similar to the type 4mm models use in the larger engines, does this scale down to allow 4mm modellers to use the larger 2mm scale motor and gearbox arrangements, just a thought.
I’ve no real knowledge of what the 2mm guys fit by way of motors but I’d rather keep the motor as large as possible in any case. As things stand, there is only a glimpse of the gears or possible just a single gear and a small area of the gearbox – it won’t be seen under normal circumstances. However, I’m planning to either paint the gearbox black or solder a piece of thin sheet to the front of the gearbox and again paint it black. That’s all that’s needed.
I did consider mounting the gearbox to the rear of the rear axle incorporating a High Level Drivestretcher so that the motor was to the front of the gearbox and wouldn’t be seen but my mounting for the rear bogie got in the way of that idea.

Are you planning on a restraint for stopping the motor from clouting the inside of the boiler when activated? It shouldn't be rigidly fixed to the frame with a sprung suspension.
Ah, to put it in the term of the CSB aficionados it’s a “Torsion Reaction Link” - or in my terminology a bit of bent wire - to stop the motor/gearbox careering back and forward when power is applied whilst not inhibiting sideways movement across the axle required by the sprung arrangement. Yes, I’d normally be sitting down thinking how best to incorporate said apparatus but for this model I’m thinking that since there is so little fore and aft movement possible because of the distance between gearbox/motor and the rear of the boiler/front of the cab that I’d leave them free to move but put in a padded arrangement fore and aft – I’m thinking either of double sided padded foam strip or just a padded Elastoplast cut down to size. With that in place there will only be around a millimetre or less of movement possible so it should do the trick without clanking noises when power is applied.

Well, that’s the plan. Nothing ventured….. as they say.


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CLASS 171 Build - Detailing (1)

Post by lindsay_g » Wed Feb 13, 2019 12:14 am


Cab Interior
A number of items are on the etch for fitting within the cab, but it’s all pretty tight in there to fit them and then pretty hard to get to at the paint stage, so I’ve elected to make much of the cab detailing a removable item (at least until after the paint stage).

Cab interior.jpg
Cab interior.jpg (30.8 KiB) Viewed 16397 times
Cab Floor
A raised floor was added within most 171’s but not catered for in the etch so I manufactured one from a simple rectangle of N/S and scribed lines to simulate the wooden floor planks. This will sit on 1mm angle bracket soldered just within the cab entrance. The cab floor can be rounded off at the corners to avoid any run of solder down the inner edges of the cab (they’ll be hidden by the tool/sand boxes), and facilitate fitting/removal.

Etch Interior Parts
Parts for 2 toolboxes and 2 sand boxes are supplied, the former being fitted front of the cab entrance and the latter rear of it. They’re all slightly oversized in width, and I tweaked them accordingly, also the lengths so that they all stopped just short of the cab entrance. With the cab floor (still loose but) in place, the 4 boxes can be soldered in place but one at a time to ensure the floor can be removed after each is added – just tack solder when the floor is in place and complete each joint from the rear once removed.

Reversing Lever, Handbrake Column, and Boiler Backplate
None are supplied as part of the etch. The brake column was fabricated from 2mm brass square tube, spare fret material, and brass wire. Reversing lever castings are available from Caley Coaches, alternatively this can be fabricated from brass offcuts (if you purchase a Caley Coaches 104 kit it has both an etched and a cast lever so if you have such a kit you may have one spare for this build!).

The boiler backplate will probably be made from plasticard as I haven’t come across a suitable casting but I’ll leave that for the meantime.

Roofs on locos are pretty predominant for the viewer so best to get them right and looking good. The “roof” on the etch is just a rectangle of brass. It needs a bit of attention to turn it into a 171 roof.

Cab Roof.jpg
Cab Roof.jpg (34.02 KiB) Viewed 16397 times
First it needs to be curved to shape, then reduced in size slightly - the roof only overhung the body by a scale .5mm all round and we’ve yet to add the angle brackets around the perimeter. The outside angle brackets were L shaped and the centre bracket T shaped. I used 5 thou brass for all the added items. It’s thin enough to be cut with scissors so that’s how the front middle and rear curved sections were cut, all oversize initially, soldered in place and filed down. The straight flat sections of the brackets were again 5 thou brass but cut with a blade against a rule – they can held in place for soldering by cutting overlength and just folding over the outer ends before applying the heat. The middle T iron was made by soldering one flat section in place then the upright (cut earlier) then the other flat section. These were all filed down when fitted but gone over for uniformity once all 3 were added. Finally the side sections were added.

It will be left as removable, but I’ll decide on how to secure it in place later. Mmm, I reckon the horizontal sections of the angle brackets are too broad so may replace them. Also, the middle bracket should be higher than the others, so another wee bit of rework required.

Water Depth Gauge
Not something I’ve seen added to many models, but this can easily be modelled – just a length of .4mm wire bent at the top and 2 small lengths of tube (syringe needle) obtainable on eBay. This can be seen in the image below.

Cab Grab Handles

Fitted handles.jpg
Fitted handles.jpg (64.57 KiB) Viewed 16397 times
Again, the Caley likes to make life interesting for us as they are tapered from top to bottom – from an estimated .35mm out to .65mm. These were made from N/S wire held in the Dremel and tapered by file and wet and dry, starting with just about 5mm out of the drill chuck then progressively moving this out of the chuck. There was then the question of the noticeable fitting at the bottom. Alan Knox had used brass pins on his 262 but none of mine were thick enough. The smallest washers I had (16BA) were way too big, but Alan’s method triggered a thought – drill the heads off brass pins and use them. Worked out easier than it sounds – a cross was filed on the pin head to centre the drill, a .7mm hole was drilled in a piece of wood, the pin inserted and the head drilled off. Needless to say some were lost before they got onto the model.

All I’m going to do at this stage is put out an appeal. I have several Westinghouse pump castings but none are really fit as they are. They all need rework and the best of the bunch is this one, where I’ve already started to open out the middle section somewhat :

Westinghouse - but from where.jpg
Westinghouse - but from where.jpg (60.53 KiB) Viewed 16397 times
Trouble is that I brought a number of castings together and I can’t now remember which came from where! My best guess is that this is a casting that came with a Caley Coaches 498 kit – can anyone confirm? Whatever, I’m going to delay work on this part in the hope of coming up with a better item – and I’m well open to suggestions.

Number plates
A set of plates has been bought from 247 Developments. I’m swithering whether to add before or after painting. Suggestions?

Plates.jpg (52.48 KiB) Viewed 16397 times
That’s enough for tonight. We’ll carry on with detailing next time around.

Last edited by lindsay_g on Tue Feb 19, 2019 12:06 am, edited 1 time in total.

dumb buffer
Posts: 499
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Re: CLASS 171 Build

Post by dumb buffer » Wed Feb 13, 2019 3:47 pm

I'm particularly impressed by the neatness of your soldering.
Two things I wondered if you are considering:- (a) weighting. With my scratchbuilt example, because it had a portescap motor / gearbox, extra lead could only go in the side tanks, the bunker, and the smokebox. It went beautifully on straight track, but even with one coach attached behind it just sat still with the wheels solemnly revolving. And I couldn't find room for more weight!

And (b) are you contemplating providing controlled sideplay to the bogie. I didn't on my model, and when it came to a bend the bogie just went straight on regardless. And I couldn't get more weight on the bogie without taking it off the drivers. A more recent Dunalistair I, admittedly in whitemetal, has spring controlled sideplay and glides round corners like a dream.

Allan F

Dave John
Posts: 198
Joined: Wed Aug 15, 2012 7:42 am

Re: CLASS 171 Build

Post by Dave John » Wed Feb 13, 2019 4:30 pm

Excellent workmanship, that is coming along very nicely.

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