Oswestry Works

Locomotive works diorama in 4mm

Tag: sketchup

Oswestry Works 2017

It has been some time since I looked at the plans for Oswestry Works, but with Modelu now more established I can start to put some time back into modelling.   I’ve picked up where I left off after meeting up with former Oswestry men, John Morris and John Dyke, who convinced me to model the machine shop.

Oswestry Works Machine Shop

The machine shop at Oswestry is now a antiques dealership, with many original features still visible including the large doors at the entrance to the inner works yard, original beams and rafters in the roof and all of the brickwork exposed.  I dropped in to get some photographs earlier in December and whilst wandering round the antique brick-a-brack  found a nice 1940’s suitcase.  It has made a nice addition to my body scanning wardrobe and still has an original GWR luggage label, marked Shrewsbury to Montgomery.

Researching the equipment in the machine shop has been helped by the book “Steam Workshops of the GWR“.  This shows the position of machine tools and fitters benches.   In the cut-away that I’ll be modelling, equipment included a boring machine, lathes and grinding machines, a wheel centre slotter and a screw cutting machine.

Many of these would have been provided by Sharp Stewart & Co who designed and fitted the works.  Grace’s Guide collection of Engineer magazine articles and http://www.lathes.oc.uk provide a number of images and drawings which will help recreate these.  Geoff Charles also captured some of these machines in use on his visit to the works in the 1950’s.

Operational / Demonstration Machine Shops

I made a few visits in 2014 to a number of machine shops around the country, including preserved examples at the STEAM museum and Manchester MOSI, both featuring belt driven machine tools.   Trips to the former GWR machine shop at the Vale of Rheidol shed in Aberystwyth and the machine shop at Didcot also helped give an idea of how a working machine shop looks and feels.

Designing the Machine Shop

Designing the works structures uses a combination of 3D and 2D CAD.  In the first stage, Sketchup is used to create a 3D mock up using photos and measurements for reference.    This mock up has very limited detail, essentially just the cuts where windows, doors and any other features will be.   The material thickness of the MDF to be used is extruded in 3D, allowing the model to be built virtually.

Once the outer dimensions and features of a wall are completed, the wall can be viewed in 2D mode and exported as a DXF ready for brickwork to be added in Draftsight.  To make this operation easier, I use groups and components extensively in Sketchup, in order to isolate individual items.  Using the Outliner gives an overview of how the components and groups are nested and provides a quick way of hiding items.   Switching to parallel projection view mode, the element can be then viewed in 2D ready for exporting.  DXF export will export whatever is on the screen, so all other items must be hidden prior.

Works Sidings & Templot

In addition to the machine shop, I’ve also added a number of the works sidings and the goods thru road to the outside of the works.  The plan is to use this area for photographs of stock and to test out new Modelu components, including GWR concrete pot sleepers, Cambrian chairs and GWR slide chairs.  I used Templot for the first time to plan the track work out and found the DXF import feature of great use.  In Sketchup turning off the roof artwork group and switching to a plan 2D view allowed for a DXF export of the mock up to then be imported into Templot.

Templot Oswestry Works.JPG

Once the trackwork was completed, this could then be exported as a solid 3D DXF and imported back into Sketchup.

Next Steps

Geoff Taylor has been giving me some great advice on how to tackle this project.  Our first plan is to trial some painting techniques of the inner walls.  Looking at photographs shows they are heavily coated in many layers of paint with the brickwork barely visible.  I’m hoping to save time on laser cutting by using a paint/powder mix to coat the walls and give them a little texture.  If that goes well, then the walls of the main works buildings will be cut.  The outer yard buildings need finishing as does the works footbridge and the outer yard wall.  The roof will be removable so some thought will be given to producing the beams and rafters using brass rod to keep it strong.

That’s pretty much where I’m up to after blowing the dust off the plans over Christmas.  I’m hoping during 2017 to get a bit more balance and be a little stricter with myself regarding free time.  Working at home has its advantages but it has been very hard to switch off and lock up the Modelu workshop!

All the best for 2017 and thanks for looking,




Pushing the envelope with a B9 resin mix

GWR 9000 Class Top Feed test print

After what was in retrospect disappointing results with Spot HT – through my own ineptitude I must add, I went back to the tried and tested  1:1 mix of B9 Creator Red and Cherry resin.  This isn’t to say one is any better than the other, but with little life left in the layer of PDMS silicone before it needs replacement I didn’t have the leeway to experiment further with Spot HT.

This last batch of prints has been more experimentation with what level of detail is possible.  Second time round I reduced the size of the whistles and the steam heating cock to be a more prototypical size, even more challenging for the printer.  After quite a few false starts (left the projector lens cap on, build table not calibrated properly, not enough resin, ultrasonic died), I finally got a successful batch of prints of the highest detail so far.

This feels like uncharted territory because I’ve not wanted to let myself believe that it was capable of this kind of detail, until I’d seen it with my own eyes, coming out of my own printer.  I firstly revisited the design of the top feed for the Dukedog, the previous version not having a recess for the pipework.  This was designed to fit 20 swg copper wire, but the printed hole is slightly tight. It was a good exercise to see how well the resin could be worked with and the small hole could be opened up easily twiddling with a small drill bit.  This top feed will end up on 9014.

The whistles came out almost perfectly, considering that some of the detail in the design was under 0.25mm it would be impossible to see with out a macro lens or magnification.  Once cured these fine parts are quite robust, they aren’t indestructible but they did handle tweezers and finger tips, positioning them and trimming away traces of Tacky Wax under a magnifying glass!  It’s the detail presented on these that has really left me speechless.

GWR Standard whistles and mounting bracket test print

GWR Standard whistles and mounting bracket 30 micron xyz print

The beauty of this resin is it’s use to complement traditional materials, in this case matching up the whistles and mount with a Comet whistle shield etch and two strands of 36 swg copper wire to represent the whistle pipework.  The whistle print stood up to the finicky task of glueing everything together well, with impatient tweezer nibs looming, third hands full, trying not to drown the details out in glue.  This is the kind of detail I was hoping to attain after a few abortive attempts last year.

So with that done I think I’m out of excuses as to why 5726 can’t be finally painted and have its correct numbers fitted!

5726 with new whistle assembly

Comet Whistle Shield Etch, 36 SWG copper wire and 3D printed whistle and bracket assembly

5726 with new whistle assembly

5726 with new whistle assembly

Injectors part II and a visit to Oswestry

In the last entry I was trying and failing to get an injector built with the soldering iron.  I had some good advice about using 188 deg solder combined with 145 deg to build up the injector without it melting into a lump, I’ll give that a go when I’m back home in Brighton.  In the mean time I’ve retried the process using super glue.  It’s been pretty successful, except I’ve not been able to make it small enough – without the pannier body to give it some sense of scale, it looks ok but it still needs to be about 20% smaller to fit between the running plate and the tanks!

74xx injector test build

74xx injector test build

For the time being I’ll put this little side project to one side, there is still much to do in Illustrator to get the works ready for the laser cutter.  Once the 3D printer is up and running it will be a good test of its abilities.

Whilst back home in Wales, Oswestry is only an hour or so away so I usually get up there to have a look around for new ideas.  The gates to the inner yard are usually closed, but by chance they were open on yesterdays visit.   This yard was situated between the machine shop (which was linked to the loco works) and the smithy. In the yard to the southside were the coppersmiths, brass foundry, engine house and the boiler house.

Oswestry Works Inner Yard

Oswestry Works Inner Yard

The yard itself had a number of wagon turn tables though by the 1950’s it looks as though only one was left in use to access a short spur off of the works thru road.  This spur was used for the loading of refuse, ash and such into wagons for disposal.  On the north side of the yard were the stores and departmental offices.

Seeing the low afternoon sun shining on the buildings got me thinking… it would be quite something to make the works a modular layout, in the same vein as Mikkel’s Farthing layouts, building the works up with 3 cut-a-away diorama’s.  This would include a 4th module to represent the works sidings and up/down main lines to the north of the works.  To get an idea of the scope, I’ve put them together in Sketchup and colour coded the proposed modules:

  • Red – Locomotive Works (Erecting Shop, Traverser Shed, Tender Shop, Loco works yard)
  • Green – Machine Shop, Offices & Stores, Inner Yard, Smithy
  • Blue – Wagon Department, Carriage Shops
  • Yellow – Up/Down main line, loops and sidings, works bridge
Oswestry Works - Modular diorama design

Oswestry Works – Modular diorama design

Oswestry Works - Modular diorama design

Oswestry Works – Modular diorama design

These views show the whole works, but I still think a cut away has the most potential, extending the cut from the existing diorama, exposing the inside of the machine shop, the inner yard, the wagon shop and the carriage shops.  Quite a challenge but building it up in manageable sections like this should make it more achievable.

Oswestry Works - Modular diorama design showing cut away

Oswestry Works – Modular diorama design showing cut away

Surprising what an afternoon wandering around in the sun can lead to!

Oswestry Works - 5/11/14

Oswestry Works – 5/11/14

A test run at scratch built injectors

I’m back in Wales for a few days and to keep up the momentum of progress I figured I’d set myself a small project, something that doesn’t take up too much space or need too many tools – making some injectors to replace the whitemetal ones with the NuCast 74xx.  By the time I’d packed the reference books, tweezers, pliers, components, lamps, soldering iron etc I might as well have brought the whole tool box, but that’s another matter.

Whitemetal kits and etched kits are completely new territory for me, so for about a year before I bought a soldering iron I read, read and read so more.  Not that it changed much, I still didn’t feel confident enough to even open the wrapper on the Dean Goods chassis, certainly not the High Level Pannier I’d bought eagerly at ScaleForum months ago, still sat neatly packed in its box… time was the main factor, I needed a clear head and some hours set aside to have a go.  Now I’ve got a bit more free time there are no more excuses left.  Soldering iron has been bought, Whitemetal kit attempted.  No turning back now!

I’d first heard of Iain Rice’s Building Whitemetal Locomotives and Etched Loco Construction through Geoff Forster’s blog Chronicles of Penhydd and I managed to find them both very cheaply second hand.  As well as explaining the whole process extremely clearly and with some humour from time to time, it’s the level of scratch built detail that really captured my attention – vacuum pipes (with pipe couplings!), backheads, washout plugs and so much more.  It was the injectors that caught my eye though as these are nearly always poorly reproduced in plastic.  So here goes, an attempt at creating one of these small Iain Rice masterpieces.

A few months ago the components were collected:

  • 1/16″ Brass Capilliary Tubing for the Injector body
  • 0.75mm Copper Wire for the steam and water pipes
  • 1mm Copper Wire for the Top feed and Overflow pipes
  • 16BA and 14BA washers and nuts for the fittings and valves

Injector scratch building materials

Before starting however I realised I had no idea what all these mysterious pipes actually did.  So a bit of reading up was the first job and thankfully the Bluebell Railway have a full description of the process, documented when they replaced the injectors on 9017:

Steam from the boiler, and water from the tank or tender, pass through a stop valves (taps) controlled by the fireman. When he wishes to increase the level of water in the boiler he turns on the water and steam valves.

Initially water passes into the injector by gravity, where it lifts the hinged combining cone flap, pushes down the overflow valve and runs out of the overflow pipe onto the ground. When the steam valve is opened, a jet of steam escapes from the steam cone. This jet has a high velocity, which it imparts to the surrounding water. At the same time the cold water starts to condense the steam jet. During condensation the volume of the steam is vastly reduced, so a partial vacuum is formed which (a) draws more water from the tank, (b) closes the overflow valve, and (c) shuts the hinged combining cone flap. The mixture of condensing steam and cold water continues to gain speed as it travels through the combining cone. It emerges from the small end of the combining cone as a jet of hot water. It then travels across the gap and into the divergent delivery cone. Here the speed of the jet is reduced, but its pressure is increased sufficiently to lift the delivery clack (non-return valve) and flow into the boiler.

To help get my head around the various pipes, valves and their purpose I put a 3D model together in Sketchup.  This is based on the 74xx, though there is an additional thinner pipe from the water inlet valve which goes into the cab – I’m guessing this is how the fireman controls the water inlet from the tanks?

74xx Injector for possible 3D Print

74xx Injector for possible 3D Print

Just getting the thing drawn on paper was a challenge, its the kind of device that no matter how many times I look at it I spot another pipe I’d not seen before, or then looking at it in reverse, on the opposite side of the tank might as well be the first time I’ve seen it.  A few sketches and the 3D model helped though and I think I’ve now grasped the concept!

For a test I’ve started out with just the basics – fitting 2 types of wire to the capillary tube and fitting a washer and nut.  Straightforward enough I thought, before I started to employ every tweezer I owned and still needed an extra hand.  After a while of remelting all the solder and the whole thing falling apart for the 10th time, I switched tactics – drown the whole unit in flux, melt the solder onto the new item to introduce and quickly jam it in place before the solder hardens.

Or alternatively, tomorrow I’ll try to do the whole lot in a 10th of the time with super glue (I’m sure it will still be a challenge though!)

Or, I’ll 3D print the body and still use the wire for piping…

Injector test build

Injector test build

Injector test build

Injector test build

Missenden Abbey 3D Printing Course

I’m fresh back from attending Missenden Abbey’s Autumn weekend with a few test 3D prints.  8 of us took up the 3D Printing course which was running for the first time, involving an introduction to Sketchup and then as much 3D printing as you could fit in!   The course was self paced so worked will with the variation in knowledge of Sketchup, with people being able to help each other out as they progressed through the course material.  Having 3 printers between 8 of us also ensured there wasn’t too much waiting around for your turn on the printer.  It was a great weekend, with so much else going on in the other rooms as well.  I was able to drag myself away from the 3D printer for a half hour or so to see Kevin Wilson demonstrating soldering and having a bit of hands on myself.  I’d highly recommend the weekend, not only was the modelling good, its a nice place to spend a weekend with good food and good company – being able to put some names to faces and chat to some of the best in the field was great.

My aims were to improve my abilities with working with some of the solid tools in Sketchup and creating complex shapes such as fillets and bevels, along with getting an understanding of how 3D designs need to be engineered with 3D Printing in mind.  Such as taking into considering overhangs, bridges etc, by either using support material or printing in multiple components.  Here’s some examples of what was produced:

GWR 9000 Class 4-4-0 ‘Dukedog’

I’m interested recreating some of the subtle variations between the many Dukedog’s seen on the Cambrian (as superbly researched here on the GWR Modelling site).  These 2 items were good first steps to try out with the printer – above footplate sandboxes (as per 9000 and 9005), tall top feed (9021, 9004, 9000 and many others).


Top Feed

The sandboxes were straight forward enough, taking the sandbox and wheel arch/splasher measurements from J.H. Russell’s Pictorial Record of Great Western Engines.  The top feed was a tougher to get right and I’m still not 100% happy with it, but it was a good test of skills using the follow me tool in sketchup.  I’d not been able to find any drawings of it before hand so it was a best guess from photos and drawings of other top feeds.

Craven Crane Hoist

This is part of the Erecting Shop crane that I have on my list of things to do for the works.  It’s a little early days to be thinking about detailing the works interior but this was a good chance to see what the printer could do.  I’ll need to revisit the 3D Design later to get it right, but this wasn’t a bad first pass.  I’ve roughly modelled the crane within the erecting shop to get an idea of scale as I’ve no drawings to work from, just photos from the surviving crane at MOSI.


Craven Crane

GWR Manor Chimney

Lastly, by far the hardest task was attempting a chimney.  I’ve been looking for a BR-era Manor chimney for about a year, the DMR model seeming to be the best production but they are very hard to find.  Next best option has to be printing my own!  Find drawings however has been a challenge, I had a quick look at the NRM but didn’t have enough time for a thorough search.  This drawing is based on the GWR Chimney (loosely!), but it was more of an exercise in learning how to make the complex curves and shapes as the chimney meets the smokebox.  After getting a headache from trying to get this to work natively with sketchups toolsets, I had to use a plugin after reading this post on RMWeb.

Manor Chimney

Finally, here are all the bits printed out!  They were made using a MakerBot Replicator 2.0 at 200mn resolution.  They certainly have given me an idea of what is possible and more importantly got me thinking about how things need to be made in order for them to be printable.  I’d already taken the plunge and bought a 3D printer before doing this course.   After reading up and also seeing Rab’s achievements with his printer, I bought a B9 Creator 1.2.  The 1.2 B9 is capable of 30mn resolution so my first job will be reprinting these pieces as a comparison.   I’ve bought the kit version of the printer and haven’t started the build as yet, I’ve another course on Monday evening at the B9 distributors in London, I think it best to go there first to see one in action before making a start.

Missenden Abbey - 3D Printing Course