Copenhagen Fields & TFW’s workshop

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Tim Watson
GER D14 4-4-0 'Claud Hamilton'
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Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

The Raven NER 4-6-2 class now has an ‘engine’ with the connecting rods roughed out and the cross heads and pistons in place. The connecting rods will require fluting, amongst other things.
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Tim
Mersey508138
LNER Thompson L1 2-6-4T
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Re: Copenhagen Fields & TFW’s workshop

Post by Mersey508138 »

That is a high quality level of skill I can only dream of achieving, well done.
Tim Watson
GER D14 4-4-0 'Claud Hamilton'
Posts: 305
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Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

Perhaps a bit crazy. Image
With such large big end bearings, it would have been churlish not to include separate brasses.
Tim
Tim Watson
GER D14 4-4-0 'Claud Hamilton'
Posts: 305
Joined: Mon Oct 24, 2016 11:37 am

Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

Holding your work whilst working on it is one of the biggest challenges in 2mm scale (and others). The simplest way is to glue the component to a bigger piece of metal to hold in the vice.  The holding area can be flooded with a puddle of fast setting cyanoacrylate and then the rod dropped into place: the glue is then ‘set’ with some accelerator liquid. The photo below shows how I set up the con rods for re-drilling the big end holes in the brasses. The measured position from the little end was marked with a fine marker pen and then the table shifted on the axis using the dial from the little end reference point: the drill more or less landed on the spot (I erred on making it a touch shorter). Removal and clean up with a scalpel blade is straightforward.
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Once it all felt pretty free, the temporary plastic insulation collar was replaced with a steel version. The top of the cross head was coated with a black indelible marker pen, to act as an anti-flux. The steel collar was cut from a 0.4mm bore syringe needle.
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A minuscule amount of this German flux was applied to the tip. This flux is excellent for steel, it is a bit ‘oily’ and very corrosive. 
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The iron is brought into contact with the pin and flux with just a small amount 145 degree solder on the tip. It boils up the flux and the solder immediately flashes into the joint, at which point the iron is removed, of course.  I have never got on with cigarette paper washers when assembling valve gear as they make the joints too sloppy. 
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The con rods are a very close fit to the slide bars at top and bottom of the crank throw, but they just kiss past, I don’t think the bars will need any adjustment. The big end will probably have a turned collar made for it. 
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The alignment on the frames, wheels and valve gear is quite satisfactory, without any nasty bends anywhere: an advantage of working to a true scale / gauge. 
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The front steps will need to be robust and well fixed as they must not touch the connecting rod (at least on one side).

Tim
Last edited by Tim Watson on Wed Feb 08, 2023 12:04 pm, edited 1 time in total.
Tim Watson
GER D14 4-4-0 'Claud Hamilton'
Posts: 305
Joined: Mon Oct 24, 2016 11:37 am

Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

Two of the things that puzzle me with the Skittle Alley are whether the reversing gear balance weight (seen above the frames) was visible when the engine was in forward gear.
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Also, at some point, it seems that the wheels had some extra square-shaped weights added to the crescent shape as-cast. My engine will be in near original condition so I suspect it would not have the additions. Anyone any ideas?

Tim
Tim Watson
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Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

Measuring spot heights on locos / rolling stock can be achieved using surface plates and gauges / markers for model construction. My take on this is to use a piece of Tufnol with some PCB  ‘rails’ set tight to gauge to locate a chassis very precisely (i.e. no side movement on the wheels). This block also has a coupling height gauge incorporated. 
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The way it is used is that a digital vernier is zeroed on the thickness of the block and ‘rails’. The block material needs to be of consistent thickness, but also quite hard and shiny to allow a vernier jaw to slide easily. The loco is positioned on the block, being held with one hand, and then the callipers used to make measurements or perhaps scribe a line for e.g. handrail stanchions.
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The photo shows that the Skittle Alley boiler height is a fraction under, but should be about right when it gets a coat of paint…

Tim
Tim Watson
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Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

The Raven 4-6-2 class is now mechanically complete. It slightly ‘stuck its elbows out’ on the slide bars when running and so a restraining wire was soldered across the back of the crocodile, using 145 deg solder. 
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https://youtu.be/EoCENm7k2bI

The driving wheels are lined out at the hub but the rims are not yet black. 

Tim
Tim Watson
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Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

Darlington works has been a bit quiet of late with a slight diversion into 4mm scale scenic modelling for the MRC’s OO layout. However, I did make the cab sides for the NER 4-6-2 class at the Missenden modelling weekend. 

Subsequently, the spectacle plate was made from quite thick brass as well as the running plate top. This is 5thou steel shim, being stronger than brass or N/S and able to take a good chemical blacking.  The cab sides were obviously made as a pair, sweated together for cutting and filing. 
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I decided not to put on the external cab window beading as it is very fine (in reality) and generally gets in the way of the black and white lining. The cab window frames are required, however, but only one is visible as the engines always ran with the rear window slid forward. Representing the rear slides was worthwhile and will also gave a greater surface area for soldering on the roof at eaves level.  The window layer was aligned using a couple of stainless steel pins through the handrail knob holes whilst soldering. 
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Next stage was to get the cab erected and the footplate extension boxes in front of the spectacle plate. 
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The rear cab roof support was made from thick brass and the whole assembly held in place with two bolts - the engine is being designed with ease of painting in mind, breaking down into useful sub-assemblies. 
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The next job will be to make the styrene pattern for the back head, which substantially fills the cab, seats and cab floor. A good job for demonstrating at Ally Pally next weekend. The loco now looks that little bit more complete. 
Image

Tim
Mersey508138
LNER Thompson L1 2-6-4T
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Re: Copenhagen Fields & TFW’s workshop

Post by Mersey508138 »

Although nearing completion I have to say what an absolute masterpiece of engineering
Tim Watson
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Posts: 305
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Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

Still a long way to go… thank you for the comment.

Tim
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Dave
LNER A4 4-6-2 'Streak'
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Re: Copenhagen Fields & TFW’s workshop

Post by Dave »

Nice to meet you today Tim, I was blown away seeing that little A2 in the flesh, amazing just does not do it justice , nor do the photos.
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Atlantic 3279
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Re: Copenhagen Fields & TFW’s workshop

Post by Atlantic 3279 »

As Dave said...
Most subjects, models and techniques covered in this thread are now listed in various categories on page1

Dec. 2018: Almost all images that disappeared from my own thread following loss of free remote hosting are now restored.
Tim Watson
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Posts: 305
Joined: Mon Oct 24, 2016 11:37 am

Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

After a very pleasant few days tutoring at the Missenden Abbey Modellers summer retreat, the tender of the skittle alley has made some progress. 

The front arrangements are quite different to what I’m used to - a bit like a BR standard in total, but that will become more apparent a little later. 
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The etchings produce some of the components, but it needs a bit extra to complete the job, in fact a bent up bit of Chiltern Green rail. 
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The sub assembly was located at the front, with a slightly increased opening for the drive shaft and then sweated into position. Image
There would definitely be a step on the LHS to allow the fireman to reach his stowed fire irons so that was made with a scrap of 10 thou nickel silver. It was made to fit across the opening, being wedged in and soldered, but with a break line filed into the strip. 
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This was then bent up and fractured leaving the step behind. The rivets on the etch could have been embossed from behind, but it was simpler to leave them as dimples rather than pimples. The beholder will still interpret them as rivets…
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The loco and tender now look much more in proportion, especially with the excellent correct pattern coal guards etched in N/S by Bob Jones. The two-component lifting lugs on the top of the tender were also fitted: they are quite insanely small!
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Tim
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Dave
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Re: Copenhagen Fields & TFW’s workshop

Post by Dave »

Words fail me.........
Tim Watson
GER D14 4-4-0 'Claud Hamilton'
Posts: 305
Joined: Mon Oct 24, 2016 11:37 am

Re: Copenhagen Fields & TFW’s workshop

Post by Tim Watson »

The Skittle Alley now has the beginning of an elegant front end with the frames, running plate, piano front and smokebox step made. The frames and piano front are removable, to aid painting and lining in the quite complex NER livery. 
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The prototype is very simple design, but has a tricky front step. 
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The piano front was milled from the same piece of brass used for the smokebox saddle. 
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The curved front was carved in using pink stones and a large abrasive rubber polishing point.
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It was then cut off and rebated on the underside to fit the running plate. 
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Meanwhile, the tricky little front step has a 6” diameter curved support and so this was made by drilling a 4mm-deep x 1mm diameter hole in some brass. 
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This was cut out, squared up and made to fit a recess cut into the piano front. 
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The two components were silver soldered together, taking care to heat up initially the large component from behind (silver solder saves problems with subsequent heating).
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The frames were cut out from nickel silver, sweated together and then separated: there were no lifting holes in these engines when first built. The front running plate is a separate piece of steel. Why steel? It chemically black very well. 
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The assembly for holding everything in the correct place, whilst soft soldering the frames to the piano front, was quite tricky. The frames were pushed against the rebate previously formed in the smokebox saddle by means of a toolmakers clamp. The small front end clamp is an orthodontic device for expanding growing palates. Black marker pen anti-flux prevented bits being soldered where they shouldn’t, as can be seen. The sides to be joined were tinned and also the top of the piano box, so that the soldering iron tip had some solder to help transfer heat - a ‘dry’ iron is quite inefficient. With plenty of liquid flux and the iron cranked up to 450 deg C, the joint was soon made!
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Painting and lining the frames will be a good deal easier with them dismountable.
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The separate running plate will eventually be soft soldered on to the brass base; previous use of silver soldering makes this all together more straightforward. The running plate is awaiting holes for the lamp irons. 
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Quite a picture-heavy long post this one, but it starts to make the engine look a bit more elegant. 

Tim
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