Craster

Dan Randall

Western Thunderer
Richard - I’ve thoroughly enjoyed reading about the design and execution of your baseboard support system and can’t wait for the layout build to start! :thumbs:


Regards

Dan
 

Richard H

Western Thunderer
Richard - I’ve thoroughly enjoyed reading about the design and execution of your baseboard support system and can’t wait for the layout build to start! :thumbs:


Regards

Dan
Thanks for your interest and your kind comment - I've actually just started on some stock building, but the next stage on the layout itself will be a start on underlay and track-laying, I think. I tend to work at what I rather optimistically describe as a moderate pace, so after finishing the series of postings about the baseboards I'll be posting a bit less frequently ... but I am trying hard to maintain momentum.
 

Richard H

Western Thunderer
The scenic section of Craster covers two baseboards with a total length of 8’ 6”.
In the past I have found it difficult to build baseboards that would enable all the features I wished for, and on some projects this barrier became insuperable. One of several reasons for this was that I found it hard to be sufficiently specific about some features like variations in ground levels actually to start building, but felt unable to proceed otherwise. The board I built for the “Low Quay” cameo was effective in many ways, but even then required later modifications; it was heavy, the integrated backscene proved unwieldy and made access to some areas difficult.

A probable underlying cause of difficulty was that I tried to integrate too many functions into the boards – a trackbed, multiple scenic levels, integral lighting, a fascia and backscene, routes for cables, etc. In all honesty, this aim exceeded my capacity to design and build it effectively. In summary, my previous baseboards showed too few features of intelligent design and too many features of “… A Cunning Plan”

Finally recognising this enduring fundamental problem led me to try a different solution for Craster, radically reducing the functions of the baseboard at the initial stage of construction. Broadly, I decided to make the baseboards as only a light but rigid core framework with two functions: primarily to provide very stable support for the trackbed and a base for features known to be at the same ground level as the track, and secondly to provide a foundation to which lightweight scenic and functional elements can later be added.

The Craster boards are essentially a well-braced rectangular frame. I tested the rigidity of such a design using 1/12 scale maquettes made of thin card, also using these to begin to develop the shape of the trackbed. These proved to be very resistant to even quite forceful twisting. This photograph shows some early planning with the maquettes:

Baseboard maquette 04 - both boards showing core structure - reduced for WT.JPG

The boards as built differ from these maquettes, being simpler, with fewer cross-members and a slightly different configuration. Each board is built on a fret of 4mm ply which forms a base-plate holding everything in alignment, as seen in this photograph showing part of the clamping/gluing process:

Baseboard - phase 1 clamped up - 211119 02 reduced for WT.JPG

The width of these frets matches the width between the support beams, so that the longitudinal sides of the baseboard lie directly on the support beams:

Baseboard frets for scenic boards 191120 - reduced for WT.JPG

Longitudinals, cross-members and diagonals are 4” deep, giving sufficient depth to mount and protect delicate equipment and electronics. Cross-members are half-jointed where they cross the front longitudinal, but all other joints are simple butt joints, glued with weather-proof wood adhesive. The entire structure is made from 4mm ply except for the ends, which are of 9mm ply. Ends, cross members and diagonals are pierced with holes to lighten the structure and provide a route for cables and cross-board connections. This basic structure is shown in the following photograph:

Baseboard core spine - east board 191124 - reduced for WT.JPG

The board in this condition was rigid and weighed about 2.5kg. The next step was to fit the trackbed, which is held on risers screwed to the cross-members and the diagonals. The use of risers obviates the need to shape any baseboard cross-members, gives enormous flexibility and provides unobstructed space directly beneath the trackbed for cable runs and access.

The risers are made as a “saddle” from three pieces of 4mm play, the two side pieces being for stabilising and fixing on either side of a cross member, and the middle piece being the spacer which sets the height of the riser. The sides of the risers were made from the cut-out triangles from the frets. The spacers for all the risers were made from a strips of ply cut at the same time with a single setting on the bandsaw, and they are very consistent:

Risers 191130 01 - Generic design reduced for WT.JPG

Provided the spacers are consistent in height, the length of the risers can vary, allowing economic use of all sorts of ply off-cuts. Any number of risers can be fitted in any position to fully support the trackbed, as shown below in position on one of the baseboards, and finally secured firmly in place with a screw from each side:

Risers 191130 04 - west trackbed risers exposed- reduced for WT.JPG

In practice the risers are arranged at a maximum interval of 9” although most are closer than that. After careful alignment at the baseboard ends, the trackbed is secured to each riser with two screws. The complete structure weighs about 5.5kg and is easily carried and manoeuvred. The following photograph shows the trackbed in position on one of the baseboards:

Risers 191130 05 - west trackbed on risers - nibs marked- reduced for WT.jpeg

In these photographs the risers for the nearest board end are not yet in place, nor are the dowels in the ends to align the baseboards.

The front longitudinal is set back from the edge of the base fret so that where cross members are jointed through it, a well-supported short “nib” is created. One of these is ringed in the photograph above. These provide fixing points for adding short cantilevers designed to hold a lightweight scenic contour onto this core framework; this will allow me to develop or modify peripheral elements of the scenery at a later time, as the layout develops, and finally to fit a cosmetic front ‘contour board’. In a similar way, elements such as supports for a flexible backscene can be added on the rear side of the baseboard core.

Taking this a step further, because the trackbed and the scenic extensions are screwed in place without glue, it would be possible, should I ever dismantle Craster, to re-use the core structure of the baseboard by fitting a new trackbed and new scenery.

Unconventional perhaps, but this approach allowed me actually to start building viable baseboards without having a fully detailed and dimensioned scenic plan, and to retain a degree of flexibility in the final external foot print of the layout.

Time will tell, but I’m hoping that this isn’t just another Cunning Plan – at least it got me off the starting line.

The next posting will describe the fiddle yard, and will complete the series about baseboards.
 
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Richard H

Western Thunderer
The fiddle yard (with apologies - this posting is long)
The baseboard which holds the off-scene train storage was the most complex to build. I wanted to store and turn three or four relatively short trains and also to be able to shunt beyond the scenic part of the layout using a track in the fiddle yard. The obvious way of accommodating a number of sidings within the length available (4 ft) was to use a traverser of some sort but it was less easy to contrive a way of turning the trains. I had developed a combination of traversers carrying cassettes while making the very short fiddle yards on “Low Quay”, but felt it to be rather clumsy in use.

Paul of Old Parrock suggested a solution to my problem; he referred me to an article in MRJ No.199 in which Robin Fielding described a small turntable/traverser that he built for his S-scale layout “Grove Ferry Junction”. His 3-track traverser was hidden behind a scenic frontage, but could be pulled backward to clear the scenery and then rotated. This mechanism inspired my solution, but I wanted to increase the length and number of tracks on the traverser and I needed to change the way it could be rotated. I did not have to worry about any sort of scenic frontage.

So far, I’ve used the word ‘traverser’ in the generally understood sense, but this ambiguous term term is likely to become confusing, so I am going to refer the part that actually carries the tracks as the track table.

I found that the width of my baseboard would accommodate five 36” sidings with sufficient traversing action to align any of them to the single entry track which led to the track on the scenic boards. It was also apparent, though, that moving the track table far enough sideways to give sufficient clearance to rotate it, and the dynamics as it rotated, would destabilise the baseboard on the trestles, probably catastrophically. I needed a way to devise a way slide the track table longitudinally along the centre line of the layout so that it would remain in balance when being turned.

Three different actions are required: a lateral sliding mechanism to traverse the tracks, a longitudinal sliding mechanism to disengage the track table to allow it to be turned, and a bearing on which it rotates. Each of these three mechanisms has to work smoothly, but with sufficient consistency to allow precise alignment of the tracks, and the whole had to be reliable and simple in operation … and within my ability to build.

I confess that at this point I could barely grasp, never mind retain, an understanding of how these three mechanisms might interact in three dimensions, and the only thing going round in circles was my thinking. In the end I decided, for simplicity, to regard the construction as a series of layers:
  • the top level, the track table, is mounted on a 360° bearing allowing rotation;
  • at the next level, this bearing is fixed on a block, and this block is held on runners giving longitudinal movement along the centre-line of the layout - these runners are fixed inside the sides of a wooden frame;
  • the ends of this frame are supported on transverse runners giving lateral movement, and these runners are mounted on a “chassis” of similar (but shallower) construction to the scenic boards.
Essentially, from the lowest level upwards, the chassis holds the frame which slides laterally, the frame holds the bearing which slides longitudinally, and the bearing holds the track table which rotates.

This general arrangement is illustrated in the following annotated photograph:

Triumph 03 - completed traverser 191226 - annotated + reduced for WT.jpeg

There are undoubtedly other and probably better ways ways of arranging the interaction between the three mechanisms, but this Bear of Little Brain had enough understanding (bear-ly enough!) to make this scheme seem viable … and buildable.

I knew that I could design it in principle, but that I must then be prepared to develop and/or modify the design during the build, because I simply did not know some dimensions beyond a nominal figure (e.g. what might be a practical clearance between any two layers), nor did I yet understand how the hardware might behave, and within what sort of tolerances. Determining some dimensions was made easier by using standard materials, as on the other baseboards.

After much research and head-scratching, I opted to use Hafele 250mm drawer runners for sliding actions, and a 160mm-square Hafele 360° bearing intended for heavy equipment and rotating seats (rated for 150kg, a massively greater load than I would ever impose). The bearing data sheet can be downloaded here: https://www.locksonline.com/docs/pdf/1310-42.PDF

One reason for choosing what might appear to be an over-specified bearing instead of a “lazy Susan” turntable type of design was that it was physically compact and therefore, I hoped, easier to fit; I also anticipated that it would much easier to contrive a way to slide a physically small bearing longitudinally than a bearing with a diameter almost as wide as the track table itself. I also suspected that an engineered unit with a ball-race might be inherently more stable than lighter pressings fitted with a “wheels in a ring” arrangement. I anticipated that in either case I may need to fit supplementary rollers to guide and support the ends of the track table.

The track table is a 36” long sheet of 9mm ply stiffened underneath with 1” strips of 4mm ply, arranged to give rigidity and resistance to twisting, and to create a central pocket to house the 360° bearing. The diamond-shaped bearing pocket incorporates an additional layer of 9mm ply laminated under the trackbed giving a thicker fixing point and also reinforcing the bracing at that central point. The photographs below show the underside of the track table and then the bearing positioned, but not yet secured, in the pocket:

Track table framing and bearing pocket underside - reduced for WT.jpg

A square “carriage” block for the underside of the bearing was laminated from three layers of 9mm ply, just large enough to provide a solid mount and secure fixings, and also thick enough to accept the fixing of the drawer runners along its sides. A minor bonus of my design became apparent, in that the block on which bearing was mounted is small enough to allow easy access to all its mounting holes.

The bearing is not quite a true square (a very minor and normally irrelevant variation in manufacture), so to aid later removal and replacement should it be necessary, the orientation of the bearing in its pocket was marked using red dots aligned with the screw-fixing holes.

Traverser table [trackbed] framing 09 showing red alignment dot on bearing - reduced for WT.JPG

These pictures also illustrate a personal challenge that the job presented; it was frequently necessary to work on the underside of a component but then invert it, or invert and rotate it, in order to check fit or mark a matching component. It was also sometimes necessary to take into account the direction in which a component was intended to slide. Working through upside-down, back-to-front, left-to-right and sliding variables made the job a bit complex. I found managing this spatial manipulation challenging and not at all intuitive, so I needed to check everything assiduously (and sometimes repeatedly) before acting.

I identified the optimum position for the runners by experimentation and measurement. The runners were fixed to the sides of the carriage block, using clamps and straight edges to ensure that the runners are as straight and level as I could fit them. This required two attempts separated by the need to plug inaccurately placed screw holes.

The next photographs show the carriage block mounted on the under side of the bearing, with the runners giving longitudinal movement fixed to the sides:

Carriage block mounted onbearing + longitudinal runners - reduced for WT .jpg

I later added a short level surface at each end for a supporting roller in case that becomes necessary:

Traverser table [trackbed] framing 12 - additional frames reduced for WT.JPG

The frame that holds the bearing block and also slides laterally is a simple rectangle made of 45x19mm softwood, carefully made to be absolutely square, and reinforced with an additional transverse piece inside each end. The runners holding the bearing are fitted inside the long sides of the frame, and the runners giving lateral (traversing) movement are fitted to the outside of the short ends of the frame:

Two sets of runners.jpeg

A wooden stop-block (not seen in the photographs) was fitted to limit the movement of the longitudinal runners, as the movement required is quite small – about 5cm is more than enough.

Both sets of runners are fitted vertically, as they are designed to be used in a set of drawers. I have seen similar runners used in traversers but fitted horizontally, that is, lying flat on their back surface between the base and the traverser table. I chose not to do this because the ball race is then working in a way it is not intended to, and over time any consequent wear may have a detrimental effect on the reliability and consistency of the unit. In their proper position the runners are rated to bear a load of up to 35kg -considerably more than adequate for this job.

The track table was temporarily fitted to the frame for testing; this showed that I would need to find a way to make fine adjustments to the levelling of the track table as it was slightly out of true.

The chassis on which the moving parts are mounted was constructed in the same way as the scenic boards, except that the ply strips are only 50mm high instead of 4”. (The change in measurement units reflects the simple fact that checking clearances and determining dimensions gave an exact figure in metric that was easier to work to than the imperial equivalent.) The ends are of 9mm ply and there is a third, intermediate 9mm ply upright cross-member to support the inner end of the fixed board holding the entry track; this also provides the fixing for a softwood batten for fixing the runners at the ends of the wooden frame.

The following photograph of the chassis during construction is annotated to show the key components and the position of the wooden frame when fitted:

Chassis bracing during assembly - reduced for WT.JPG

Fitting the track table/wooden frame assembly into the chassis required careful measurement, then trial and adjustment and a little sanding to ensure that the runners at both ends were free-running but without play; the job was essentially straightforward, though, and again clamps and straight edges were used to ensure accuracy.

At this point, the mechanisms all worked as hoped except that, even after taking great care, the track table was slightly out of true; it lay at the right height, but with a tilt to one side when brought up to the fixed entry track surface. Methodical testing revealed that the problem lay in the mounting of the 360° bearing under the track table. The solution was to put a thin shim (cut from an old, extremely thin kitchen cutting mat kept in the workbench) under one corner of the bearing immediately under the track table. The mounting plates of the of the bearing are of thick steel, strong enough not to distorted by this shim. This was a “trial and error” procedure which actually worked first time, so that when rotated the track table now aligns vertically to within about a 0.5mm, and exact alignment will be ensured by the track locating bolts without undue pressure being applied to the table.

Beneath the fixed entry track is a void, to which I fitted a floor to provide a small storage compartment, capable of accepting two “Really Useful” 1.7ltr boxes – really useful for storing spares, fixings, etc. The finished assembly looks like this, although hardware (such as locking and locating bolts) is not yet fitted:

Triumph 01 - completed traverser crop reduced for WT.JPG
The final three photographs show the complete assembly in situ under trial, on the afternoon of 24th December 2019 – and making for a cheerful start to Christmas celebrations:

In-line setup in operating position - reduced for WT.JPG

In-line setup  - traverser clearance in rotation - reduced for WT.JPG

In-line setup - traverser in widest position - reduced for WT.JPG

The baseboard ‘system’ is now structurally complete. The level support beams ensure vertical alignment between boards, with brass dowels in the board ends ensuring horizontal alignment, and when erected the boards are held together by one 2” single-handed ratchet clamp at each joint.

This completes the series of postings about the baseboards for Craster. Some finishing work is still needed on them before beginning track-laying, but I am currently taking a break to work on a locomotive kit. I shall report progress from time to time.

Thank you for reading so far – you’ve been very brave!
 

Yorkshire Dave

Western Thunderer
Beneath the fixed entry track is a void, to which I fitted a floor to provide a small storage compartment, capable of accepting two “Really Useful” 1.7ltr boxes – really useful for storing spares, fixings, etc.

Could you install a lockable drawer - saves having to carry two boxes?

As a thought - rather than have the levelling bolts/feet at the bottom of the trestles could they have been placed between the top of the trestle and the box girders or fitted to the top of the box girders or underside of the baseboards. This would save crawling about on the floor adjusting the feet and bobbing up and down to see the spirit level.
 

jonte

Western Thunderer
Ingenious, Richard; clever stuff.

I’ve a 360’ bearing squirrelled away somewhere after salvaging it from my broken swivel chair. Thoughts had crossed my mind that perhaps one day it could serve a similar purpose to yours, although I have neither your ingenuity nor skills to make it work. Especially not in a such a clever design as this anyway.

Jonte
 

Richard H

Western Thunderer
Could you install a lockable drawer - saves having to carry two boxes?

As a thought - rather than have the levelling bolts/feet at the bottom of the trestles could they have been placed between the top of the trestle and the box girders or fitted to the top of the box girders or underside of the baseboards. This would save crawling about on the floor adjusting the feet and bobbing up and down to see the spirit level.
Thanks for your interest, and your suggestions. I don't really need a lockable drawer, but the storage space can be used flexibly - I mentioned the boxes because I use some and they happen to fit the space. I'm sure that once the layout is in use that space will become a hole with a role. To be honest, I didn't think of putting a leveller at a higher point - I'll give it serious thought if I need a Mk.2.
 
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Richard H

Western Thunderer
Ingenious, Richard; clever stuff.

I’ve a 360’ bearing squirrelled away somewhere after salvaging it from my broken swivel chair. Thoughts had crossed my mind that perhaps one day it could serve a similar purpose to yours, although I have neither your ingenuity nor skills to make it work. Especially not in a such a clever design as this anyway.

Jonte
Thanks, Jonte - why not have a go? The design I arrived at can be readily adapted, as the only really tricky part is dealing with the tolerances and clearances, and trying to build in some scope for adjustments. It would definitely be worth having a look at the article in MRJ 199, though, that's where the original idea came from, and it's very neat. I don't consider myself particularly inventive but I actually quite enjoyed the challenge of adapting that idea to make it work in my situation. I spent a lot of time thinking (a good excuse for procrastinating at a tricky part) and checking things before attempting the next task, and a lot of that thinking seemed to be about how best to either avoid or recover from potential errors.
 

AdeMoore

Western Thunderer
The scenic section of Craster covers two baseboards with a total length of 8’ 6”.
In the past I have found it difficult to build baseboards that would enable all the features I wished for, and on some projects this barrier became insuperable. One of several reasons for this was that I found it hard to be sufficiently specific about some features like variations in ground levels actually to start building, but felt unable to proceed otherwise. The board I built for the “Low Quay” cameo was effective in many ways, but even then required later modifications; it was heavy, the integrated backscene proved unwieldy and made access to some areas difficult.

A probable underlying cause of difficulty was that I tried to integrate too many functions into the boards – a trackbed, multiple scenic levels, integral lighting, a fascia and backscene, routes for cables, etc. In all honesty, this aim exceeded my capacity to design and build it effectively. In summary, my previous baseboards showed too few features of intelligent design and too many features of “… A Cunning Plan”

Finally recognising this enduring fundamental problem led me to try a different solution for Craster, radically reducing the functions of the baseboard at the initial stage of construction. Broadly, I decided to make the baseboards as only a light but rigid core framework with two functions: primarily to provide very stable support for the trackbed and a base for features known to be at the same ground level as the track, and secondly to provide a foundation to which lightweight scenic and functional elements can later be added.

The Craster boards are essentially a well-braced rectangular frame. I tested the rigidity of such a design using 1/12 scale maquettes made of thin card, also using these to begin to develop the shape of the trackbed. These proved to be very resistant to even quite forceful twisting. This photograph shows some early planning with the maquettes:

View attachment 116368

The boards as built differ from these maquettes, being simpler, with fewer cross-members and a slightly different configuration. Each board is built on a fret of 4mm ply which forms a base-plate holding everything in alignment, as seen in this photograph showing part of the clamping/gluing process:

View attachment 116370

The width of these frets matches the width between the support beams, so that the longitudinal sides of the baseboard lie directly on the support beams:

View attachment 116371

Longitudinals, cross-members and diagonals are 4” deep, giving sufficient depth to mount and protect delicate equipment and electronics. Cross-members are half-jointed where they cross the front longitudinal, but all other joints are simple butt joints, glued with weather-proof wood adhesive. The entire structure is made from 4mm ply except for the ends, which are of 9mm ply. Ends, cross members and diagonals are pierced with holes to lighten the structure and provide a route for cables and cross-board connections. This basic structure is shown in the following photograph:

View attachment 116372

The board in this condition was rigid and weighed about 2.5kg. The next step was to fit the trackbed, which is held on risers screwed to the cross-members and the diagonals. The use of risers obviates the need to shape any baseboard cross-members, gives enormous flexibility and provides unobstructed space directly beneath the trackbed for cable runs and access.

The risers are made as a “saddle” from three pieces of 4mm play, the two side pieces being for stabilising and fixing on either side of a cross member, and the middle piece being the spacer which sets the height of the riser. The sides of the risers were made from the cut-out triangles from the frets. The spacers for all the risers were made from a strips of ply cut at the same time with a single setting on the bandsaw, and they are very consistent:

View attachment 116373

Provided the spacers are consistent in height, the length of the risers can vary, allowing economic use of all sorts of ply off-cuts. Any number of risers can be fitted in any position to fully support the trackbed, as shown below in position on one of the baseboards, and finally secured firmly in place with a screw from each side:

View attachment 116374

In practice the risers are arranged at a maximum interval of 9” although most are closer than that. After careful alignment at the baseboard ends, the trackbed is secured to each riser with two screws. The complete structure weighs about 5.5kg and is easily carried and manoeuvred. The following photograph shows the trackbed in position on one of the baseboards:

View attachment 116375

In these photographs the risers for the nearest board end are not yet in place, nor are the dowels in the ends to align the baseboards.

The front longitudinal is set back from the edge of the base fret so that where cross members are jointed through it, a well-supported short “nib” is created. One of these is ringed in the photograph above. These provide fixing points for adding short cantilevers designed to hold a lightweight scenic contour onto this core framework; this will allow me to develop or modify peripheral elements of the scenery at a later time, as the layout develops, and finally to fit a cosmetic front ‘contour board’. In a similar way, elements such as supports for a flexible backscene can be added on the rear side of the baseboard core.

Taking this a step further, because the trackbed and the scenic extensions are screwed in place without glue, it would be possible, should I ever dismantle Craster, to re-use the core structure of the baseboard by fitting a new trackbed and new scenery.

Unconventional perhaps, but this approach allowed me actually to start building viable baseboards without having a fully detailed and dimensioned scenic plan, and to retain a degree of flexibility in the final external foot print of the layout.

Time will tell, but I’m hoping that this isn’t just another Cunning Plan – at least it got me off the starting line.

The next posting will describe the fiddle yard, and will complete the series about baseboards.

Entirely amazing loving your planning and concept models, it’s all really clever and inspiring stuff. Brilliant read on to fiddle yard now must get reading.
Cheers
 
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Richard H

Western Thunderer
Entirely amazing loving your planning and concert models, it’s all really clever and inspiring stuff. Brilliant read on to fiddle yard now must get reading.
Cheers
Thank you for your interest, and the kind comment. I must stress, though, that I've based much of this upon other people's ideas, particularly Robin Fielding's traverser, using risers as in the well-established L-girder system, and inspiration from Iain Rice's thinking and Gordon Gravett's. I think that, in essence, my approach is a compilation of ideas and techniques that I've applied in my own way. I've enjoyed finding what I hope will prove to be pragmatic ways of making the boards ... all I have to do now is use this foundation and build the railway part!
 
Craster Locomotives

Richard H

Western Thunderer
Locomotives for Craster – introduction and first progress report
While researching the ficts about Craster I was shown a very tattered ‘Book for Boys’ in which, inside the cover, an unidentified boy living in Craster had from time to time listed engines he had seen in the station. We know he lived in Craster because part of a childlike address is visible beside a torn corner of the flyleaf:

Whi
Craste
Northum
England
Great Brita
The World
The Universe​

The list is incomplete and undated, and not particularly organised, but when compared with information gleaned from NER documents it confirms that services on the Craster branch were operated by unassuming “workhorse” engines of the NER.

It is possible to extrapolate the following ficts with some certainty: Class B 0-6-2Ts usually worked the good services and, occasionally, passenger trains. Passenger services were more usually worked by 0-4-4Ts of Class BTP, originally hauling “old carriages” but later with autocoach trains. From time to time Class A 2-4-2Ts also appeared, as well as other types including examples of Class O 0-4-4T and Class E1 0-6-0T, and tender engines such as Class C 0-6-0 and Class 398 0-6-0. Occasionally the lad’s notes give tantalising glimpses of more exotic engines, usually older and small passenger classes perhaps seen on excursions trains or summer specials. He also noted one of NER’s two petrol-electric Autocars appearing on the branch for a short time.

For my interpretation of Craster I decided that the first locomotive to build had to be a Class B 0-6-2T. This class included engines built both as compounds and as simples, but all were eventually converted to singles. Originally intended as goods engines, some were fitted with Westinghouse brakes and proved to be effective mixed-traffic engines; over an extended period all the engines were modified with enlarged tanks and bunkers. Compound and simple engines were both designated as ‘B’ and ‘B1’ at different times in a series of confusing changes but, for convenience, I am using the term ‘Class B’ to include both types, as this was the final NER designation after the entire class was rebuilt. In LNER and BR days they were designated Class N8.

I plan to construct a ‘simple’ Class B in unrebuilt condition with low tanks and bunker. It’s a long time since I last made a locomotive and I feel some sense of apprehension. I shall describe the work at intervals, and this first posting illustrates initial progress on the chassis.

The model is made from the London Road Models (LRM) etched-brass kit. I made a conventional start by collecting as much information about the prototype as I could find, then reading the instructions, naming the parts, trying to identify things on the frets and in the bags, and making provisional decisions about basic compensation, choice of motor and gearbox, etc., before ordering the additional components I needed.

Starting work on the chassis, I had to re-discover skills long unpractised, and this led to my first Big Mistake … I was so engrossed in almost regaining control of a piercing saw while cutting out the apertures for the hornblocks that I forgot to stop (!) after the two front axles and I cut out all the apertures, thereby removing the location for the fixed, driven rear axle, which also provided the datum for the ride height. (Imagine here a scream, as torn from Dante’s tortured souls, fading slowly into the stygian darkness of self-recrimination.)

Luckily I’d marked the axle centre line on the frames as a guide for the compensation beam so I could still establish the datum (visible in the photograph below). My solution was to fit hornblocks and bearings for all the axles but to solder up the bearings for the rear axle to make it rigid. I used hornblocks from High Level Kits (HLK) and reinstated the rear axle bearings:

Class B - 200105 01 - frames + rear HLK hornblocks - reduced for WT.jpeg

The next stage was to align the mainframes and solder in the first spacers:
Class B - 200105 08 - rames with front + rear spacers - reduced for WT.jpeg

Supporting the chassis whilst I manipulated both LRM axle alignment jigs and the forward hornblocks required several more fingers than I have at my disposal. I do not have a chassis jig, but I devised a simple but level support by mounted pieces of extruded aluminium angle strip on a substantial piece of softwood:

Class B - 200106 - 01 - Chassis holding rack - reduced for WT.jpeg

In use, it simply supports the axle jigs at the same height, and overcomes one of the variables in holding things securely:

Class B - 200106 - 02 - Chassis holding rack in principle - reduced for WT.jpeg

By using small clamps made from aluminium hair grips (easily cut and bent into useful shapes) components can be held in place:

Class B - 200107 - Chassis holding rack the principle works reduced for WT.jpeg

Having established that this seemed to work in principle, the next step was to solder the bearings to fix the rear axle in place. I found that the HLK hornblocks gave the right height for the axle when they were aligned with the bottom edge of the mainframe, which made setting them comparatively easy. Using an LRM jig to align the bearings across the frame I positioned them carefully, checking in as many ways as I could devise that the axle would lie level and horizontal (e.g. ensuring the axle was in the right place, using a stop to align the hornblocks to the frames, and sighting along the chassis to match axle to the front spacer), then clamped and finally soldered them.

With the rear axle bearings spot-soldered in place I felt able to construct the coupling rods and use them to set the distances between the axle bearings in the hornblocks, clamp everything in place, and apply solder:

Class B - 200109 - 04 coupling rods test on LRM jigs - reduced for WT.jpeg

... resulting in this:

Class B - 200121 - 02 - chassis mainframes on LRM axle jigs - reduced for WT.jpeg

The hornblocks are fixed, the bearings on the forward axles move freely, and the axles are aligned to the coupling rods. The structure will remain weak, though, until cross-members such as the motor mount and pivots for the brakes are fitted.

At this stage I was able to assemble and test-fit the pony truck, which fits directly below the rear spacer on the mainframes. In doing so I realised that the rear spacer was slightly out of true, and had to re-align it. For the first time I could see the overall length of the chassis ...

Class B - 200121 - 03 - chassis approx aligned + unfixed - side - reduced for WT.jpeg

… and examine the fit and action of the pony truck under the rear spacer:

Class B - 200121 - 05 - chassis approx aligned + unfixed - above - reduced for WT.jpeg

Using a ruler to ensure that each side frame was straight, together with LRM axle jigs to retain alignment between each pair of bearings, the brake pivots were soldered across the frames. This had an immediate stabilising and stiffening effect on the mainframes.

Class B - 200123 - 04 - brake pivots fitted across the frames - reduced for WT.jpeg

The brake pivot wire is seen to the right of the hornblocks. This photograph also shows that I need to refine my soldering skills further, and that the work still needs some cleaning. The green splodge on the top of the bearing and the hornblock are marks I applied when matching bearings to hornblocks.

The next posting will deal with the gearbox and the drive to the rear axle.
 
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AdeMoore

Western Thunderer
Liking The Class B Richard, I think your being a bit hard on yourself with the soldering! Nowt wrong with that as far as I can see. I Would dearly love to be able to solder as good as that!
Cheers
 

Richard H

Western Thunderer
Liking The Class B Richard, I think your being a bit hard on yourself with the soldering! Nowt wrong with that as far as I can see. I Would dearly love to be able to solder as good as that!
Cheers
Thanks Ade - that's kind and encouraging. I do try to be neat, but I still end up having to do a fair bit of cleaning as I go along. I've also just realised that two of the photos don't appear in the text as they should - I'll see if I can fix that. (a little later - I think I've fixed it and added a photo that seemed to be missing.)
 
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jonte

Western Thunderer
Well saved, Richard ;)

Ingenuity displayed yet again with the home-made jig. I’ve never seen it done before, but a great money-saving device.

I’ve been toying with purchasing the LRM Jinty for some time, despite building a GWR themed layout. Why?

Well, in the late BR period in the NW of England in which it’s set, there’d have been a real mixed bag of locos about, so that alone would have justified it’s presence. The ficts are there for all to see.

But I’m thinking further ahead, here.

Despite a couple of lukewarm attempts, I’ve yet to seriously broach the subject of P4 or even build my first kit. The problem I’ve found with say the GWR from this aspect is that while there’s a host of locos to choose from, the same can’t be said for coaching stock. With LRM, this part of the problem is solved (there’s also a wealth of motive power to model the railway in its earliest days), so all I need to do now is cut my teeth on that first kit and here I feel the humble Jinty is the ideal subject to introduce me to this ‘black-art’ side of the hobby. I hope.

With this mind, I now have another reason to enjoy your already enjoyable thread.

Best regards,

Jonte

(Apologies for the absence of the full-stops in respect of the abbreviations but I’m just being trendy ;)).
 
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