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To stimulate discussion, post photos and exchange ideas, and (being an open public forum) help encourage others to try S scale modelling.

Brecon and Merthyr Stephenson 2-4-0 locomotive parts and assembly.


Timber
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Hello

 

Over the past couple of years I have put together the etched components and 3D printed parts to build a S Scale model of the above locomotive.  Recently I have shared the parts with another member and so decided to put the build details here.

 

Many members of the society scratch build and very few would be interested in this prototype, but I will share what I have and if anyone else is interested then please make contact.  All parts will be available at cost, this is my hobby not a business.

 

I am not an expert kit builder or modeller and some of my methods may not be the best.  Happy to take suggestions for improvement.  

 

The underlying principle is to keep the model simple - whilst the model is dimensionally reasonably accurate it is not a fine detail model....but it can be made to run nicely with simple hand tools and a soldering iron.

 

I will document the build over a number of weeks.....but here is a starter.

 

Prototype info

 

The B&M ordered six of these locos and the design was based on a copy of the GWR metro tank.  B&M aquired six locos, between 1888 and 1904.  Five of the engines survived into GWR ownership and were assigned numbers 1402/12/60/52/58 but only one (No 11) actually carried a GW number 1460.  It is unlikely that 1460 actually performed operational duties in the GWR but it does open the door for anyone modelling the GWR to use this model.

  

stephenson.JPG

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The model is a mix of etched and 3D parts the attached picture shows the split.  The 3D printed parts include all the brass parts that are availble in brass on plastic printed 3D depending on budget.

etch verses 3d.JPG

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Before folding there are some changes to the etch that I would recommend.  Next time I refresh the artwork I will add these in now but for now these changes will have to be made by hand.

 

If you look at the photos of my model you will see the sand pipes at front and back.  These attached to the body.

 

This is fine and work OK.  But for other locos I am working on I decided to fit the sand pipes to the chassis.  Otherwise when the body is removed from the chassis, the body sits on the sandpipes and this creates a point of weakness.  Hence why this change is applied.  

 

1mm holes should be drilled in line with the blue crosses - these can support handrail knobs that will then hold the sandpipes.

 

There is also a small adjustment required to the rear spacer....just file the tag by 0.5mm so it will snuggly fold into the frame.

adjustment.JPG

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Now fold the frame.  Once folded place the top of the frame upside down on a flat surface, i use a spare porcelane floor tile; push down, check the faces are square and solder.

 

Look carefully at the centre spacer, this folds to about 30 degree to allow clearance for the plunger pickups....front dummy cyilinder is folded to the same angle as the dummy plastic 3D printed cylinders....

 

All etches joints are on the inside of a fold.....

frame.JPG

Edited by Timber
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Once the chassis is soldered the next task is to fit the bearings....

 

The photo is not very clear but the approach is simple.  The bearings are available from Markits.  The brass bearing has a 0.4mm slot on each side.  The slot is slightly offset.  

 

Firstly touch the side of the frame slots with a file to form a very small taper.  The frame etch thickness is 0.5mm so this small adjustment will help with fitting the bearings.  But it really does only require the lightest of touches.

 

The leaf spring etch is then folded forward towards and the bearing is dropped in behind the spring with the thinest edge, between the slot and the face, facing outwards.  The bearings should gently push home and then the leaf springs straightened to keep the bearings secure.

IMG_2595.JPG

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The beams can sit directly on the thick side of the bearing but given there is very little metal I recomend that small boots are fitted to sit on top of the bearings.

 

These are made from spare strips on the etching.  

 

Offer the bearing to the outside of the frame, mark with a pencil and solder the boots on.

markup.JPG

boot.JPG

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Now with a 10BA countersunk screw, fit the beam with a half nut to provide clearance in the frame and a full nut soldered in possition to hold the beam.  Screw is cut to size and soldered.   

assembly.JPG

Edited by Timber
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Once first side complete repeat for second side and the compensation for the drivers is complete.

 

The motor and gearbox is designed to drive the trailing driving wheel.

complete side.JPG

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Next I fit the brake hangers....with hindsight these could be fitted before the beams but the beams are 'springy' enough to be moved out of the way.

 

I use dress making pins, scratch the crome off and then solder.  I finish with a 14 BA nut on the wheel side of the frame just to help create more of a mechanical join as one of these working lose after painting is a pain.  

brake hangers.JPG

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Next up is to create the pivot for the leading 3'6" wheel.  Within the etches there is a sub frame that can be fitted so that it rocks the wheel.  But more recently I have used a simple 6BA bolt that the axle rides on.  The benefit of this method is that once the wheels are on the loco, it easy to adjust the bolt to level the loco....not pretty but seems to work just fine. 

 

The bolt is simply fitted in place by soldering a nut into the frame over the small hole at the front of the chassis.

front sus.JPG

Edited by Timber
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Now I have three points of contact that, with the help of gravity and simple mechanics, will keep the loco on the track.  This is a well proven system that is simple and robust.

comp.jpg

Edited by Timber
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Finally using 7mm handrail knobs and a variety of dressmaking pins the sand pipes and drain plugs are added.  

 

Once complete I will clean off all the excess solder and give it a good general clean up but not paint until I have the motor and gear box possitioning clearly worked out..something that i will do after some of the key body parts are assembled.

 

My appologies if I have laboured any points.....I recognise that for many people reading this I am stating the obvious but I am adding the detail for completeness.....

finish.JPG

Edited by Timber
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On to the body.....

 

Starting with the footplate.  If the sandpipes are attached to the frame and not the body then the holes circled in red can be filled with solder.

 

If Clack valves to the front of the boiler are to be added (later versions of the prototype) then two 1mm holes will need to be drilled where the green cross hairs intersect.

 

Depending on the motor choice the area in orange can be removed to create more clearance.

 

 

crosswires (1).JPG

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