Rebuilt Bulleid West Country 3D CAD designed & mft in 3.5 in

[masahiraoka]

• I'm starting this thread to describe our project which is now into its fifth year - the development of a 3D CAD designed and manufactured rebuilt SR/BR West Country Pacific.

• I'll tell the story to date in a series of 20+ Posts uploaded every couple of days, beginning with a brief outline of my and my CAD engineer Phil's background

• I've had a 25 year interest in scale steam locos, unfortunately not as model engineer rather as a collector / operator focused on a complete collection of the British Pacifics in 3½ inch gauge.

• This lack of hands on model engineering is through no lack of interest but rather a lack of time because of a crowded business career

• For part of my career I was a professional engineer working in product development and sales and marketing for high tech design and manufacturing companies.

• Most relevantly this experience was with Peter Farley at Farley Manufacturing who design and build CNC controlled profile cutting machines.

• At Farley, in the late 1980’s we developed a world first – the Fabricator- a combined high-power plasma and oxy profile cutter with a high-power drill and tool changer – the first customer was British Steel (see photo). British Steel purchased the prototype right off the exhibition stand in 1987.

[masahiraoka]

• The second photo shows Dorothy Mather, widow of Arthur Peppercorn, initiating the profile cutting of A1 Tornado’s frames on a Farley Trident oxy and plasma profile cutting machine at British Steel in Leeds on 13th July 1994

• All the 3D CAD design (utilising IronCAD software), production engineering and trial locomotive construction work is being undertaken full time by Phil, an engineer with nearly 40 years of professional mechanical and production engineering experience including extensive experience with 3D CAD systems.

• In parallel to his professional engineering career, Phil has been a model engineer for nearly 50 years having built a pair of 5 in. Simplexes and rebuilt several larger locos.

• Construction of the prototype has commenced with all the work being undertaken by Andrew, a very experienced model engineer who is well-known in Australia.

[masahiraoka]

• Before launching into a description of our project it is worth reflecting briefly on the full-size locos



Extract from BR dwg no. W11769

• As with the Merchant Navies, the West Countries could generate great power using mediocre quality fuel, due largely to Bulleid's excellent boiler, exhaust and draughting.

• They also ran smoothly at high speed, but they were also beset with the same technical problems of their larger sisters; adhesion and maintenance problems, high fuel consumption and poor driver visibility.

• The rebuilding solved most of the maintenance problems whilst retaining the excellent features of the original design. 60 were rebuilt and 50 were not.

• Repair costs were reduced by up to 60%, and coal consumption by up to 8.4%.

• However, the Walschaerts valve gear made the rebuilds heavier and prone to hammer blow on the track, a complaint that was not evident with the original design.

• The increased weight reduced their route availability, meaning that they could not be used on certain routes available to as-built examples, such as the line to Ilfracombe.

• For a range of reasons there are nearly twice as many preserved full-size West Country and Merchant Navy Pacifics as all the other British Pacifics put together.

• In preservation, with their technical problems solved, they’ve proved popular powerful main line steam locomotives.

[niels]

All UK pacifics in 3D is a wonderfull plan.
Thank You very much.
What was reason for less than perfect balance on the rebuilt WCs if the new mid piston was same mass as the old one?
Are You including a Thomson A2 in collection?
Am not getting younger and if it is the last I wont admire it.

[masahiraoka]

Niels
the only Pacific we're working on is the Bulleid rebuilt West Country.
the reason for this will become obvious in my next post.

[masahiraoka]

• As mentioned, my collection of British Pacifics is complete except for a SR/BR rebuilt Merchant Navy / West Country hence this project

• There are many scale designs for the LNER and BR Pacifics, and to a lesser extent LMS.




• There is however, only one design of an SR Pacific, the rebuilt Merchant Navy, Ariel, by Keith Wilson in 5 inch gauge.

• Keith Wilson’s Ariel design was published in Model Engineer magazine between October 1984 & November 1987 and the drawings are now supplied on 25 sheets by MJ Engineering

• The design for Ariel contains a very significant number (120+) of major errors and many omitted dimensions, and is really a cross between a Merchant Navy and West Country locomotive. This list can be downloaded as a pdf file from the relevant page on Rob Speare's Building Bulleid's Locos website, see www.bulleidlocos.org.uk/_pdfs/Ariel_errors_M.pdf

• This occurred because Keith commenced his design for the Merchant Navy with a set of West Country drawings believing, incorrectly, that the various bracket fabrications were common between the two locomotives.

• The design for Ariel has therefore long been known as a difficult one to build with each model engineer having to sort out the mistakes for themselves.

• To quote the MJ Engineering website, “This is the model that everyone wants to build but very few have the staying power. It is very complicated, it would be foolish to say otherwise, and is probably best suited to the experienced model engineer who already has an engine to play with”.

• Despite the design errors more than half of the Merchant Navies described on Rob Speare's excellent website, www.bulleidlocos.org.uk, are based either entirely or to a substantial degree on Keith’s Ariel design.

[niels]

Thank You for Your way planning.
Are You planning to publish/distribute the 3D model?
Kind regards
Niels

[masahiraoka]

Niels
perhaps in a year or so when we’ve completed the design and built a prototype to check the design
regards Martyn

[niels]

Mar 29, 2020 15:29:35 GMT masahiraoka said:

Look forward to that.An uncontrolled Beta version will be nice also as I am to old to build but not to enjoy a good design.

[masahiraoka]

• I was fortunately able to purchase a 3½ inch gauge as-built Merchant Navy, Anchor Line, scratch designed and built by Len Gillet in the 1970's

• Anchor Line has three cylinders with slide valves (using castings for LBSC’s Hielan Lassie) driven by Stephenson’s valve gear scaled down from Martin Evans Torquay Manor with the outside cylinder eccentrics on the crank axle and the inside cylinder eccentrics on the rear axle.

• The boiler, based on LBSC’s Pamela Pacific design, was in fact oversized vis a vis scale full size and as a result the loco is ¾ inch too tall but it produces lots of steam!

• Maybe it’s because of the correct (as per full size) five nozzle blast pipe and large diameter chimney (larger than that specified for Pamela)

• Len entered Anchor Line in the 1981 IMLEC efficiency trials when it came sixth overall with the best 3½ inch gauge performance, (the others being 5 inch gauge).

• During his 1981 run Anchor Line pulled six adults for 30 minutes for an average draw bar pull of 0.273 hp, a specific fuel consumption of 10.8 lb/dbhp hr. and a thermal efficiency of 1.64%

• Len completed the loco in 1978, and up to 1994 he had steamed it 67 times mostly hauling passengers. On one occasion it performed for 7 hours straight.

• For the full story of Len's loco see the relevant page on Rob Speare's Building Bulleid's Locos website; www.bulleidlocos.org.uk/_mnOr/mnLen.aspx

• See this video on YouTube of Anchor Line running a full lap of the Walton track in Sale, with thanks to LMS4767; www.youtube.com/watch?v=WLP_Lxs7vzk






thanks to Rob Speare for the two photos above



thanks to Graham Jones for the photo above

[Oily Rag]

Mar 29, 2020 15:29:35 GMT masahiraoka said:

Niels
perhaps in a year or so when we’ve completed the design and built a prototype to check the design
regards Martyn

Yes, prove the drawings and make the corrections with the prototype. Modern CAD facilitates this. To me this is ethical.

[masahiraoka]

• There have been a couple of designs published for West Countries but to my knowledge these have very rarely been used. These designs are

• Ernest Steel’s (Henry Greenly’s son-in-law) 7¼ inch gauge as-built West Country design, (1965), ~80 drawings originally marketed by Bassett-Lowke now sold by Maxitrak




• Chris Barron’s 2½ inch gauge as-built West Country design, (1993)



• After carefully examining these designs and Keith’s Ariel we decided to ignore them all and start a new design from scratch.

• The new design is working from 750+ SR and BR original drawings for both the as-built and rebuilt Merchant Navy and West Country locomotives.

• The drawings, all from NRM in digital form have been cleaned with Scan2CAD software. The cleaned drawings have been shared with the NRM so that future model engineers have higher quality material to work with.

• The Scan2CAD software is easy to use and with a bit of work creates as-new versions of poor quality scans of old drawings, see the before and after sections of a drawing below.

[Doug]

I like this project, I have been working on a scale 2.5” merchant navy sir Keith park, I also have ended up jumping off published designs as they were quite poor, my 3D model maybe of help to you if you want a copy, I haven’t got really far but the front bogey is complete.

[masahiraoka]

Thanks Doug. Yes I’ve seen your thread over the years. Thanks for the offer to share your work to date but we have completed the bogie along with much else, as you’ll see in a post or two the engine itself is nearly complete. Regards Martyn 

[masahiraoka]

• The general design specification for the new rebuilt West Country is fairly conventional featuring the following:-

    o Three cylinders with Walschaerts valve gear

    o 100 lb/sq. in. AMBSC (Aussie code) / CE approved boiler with tapered barrel, Belpaire fire box, combustion chamber with water tubes and 3 element radiant superheater.

    o Steam injector, eccentric driven mechanical pump, double acting emergency hand pump.

    o Drop down fire grate and ash pan for cleaning and emergency fire disposal

    o Easily removable combined ⅔ split smoke box + smoke box door + ring to allow easy access to the blast nozzle, blower and superheater

    o Large easily removable cab roof section for ease of driving

    o Remote lubrication system comprising readily accessible pots and fixed plumbing to all internal plain bearings including; axle boxes, cranks, eccentrics, slide bars

• What is not conventional is the level of detail in the 3D CAD design which is being combined with 3D printing techniques. The 3D CAD design is very detailed so parts can be made at any scale from 2½ to 7¼ inch gauge possibly even 10¼. Limitation on scale is currently a function of the size and economics of 3D printing.




• This photo shows the Inside Motion and Reversing Screw brackets printed in PLA plastic for 3½ and 7¼ inch gauge



• And this photo showing the centre cylinder pattern printed for 3½ and 1¾ inch gauge

[niels]

Lovely model.

Are these plastic 3D printed parts intended to be used as lost wax  casting parts and how many % bigger than final parts?

[Doug]

I would have to say I for one am VERY excited about this project, how are you thinking to commercialise the 3D model it would save me at least a year of work if I could buy a copy? The frame and stretchers are relatively easy to make, the three cylinder blocks and wheels are the biggest stumbling blocks as castings are crazy expensive and hard to find and in some cases impossible, I plan to make mine by 3D CNC machining.
Also are you going to use outside admission or swap to the easier normal porting?
Thanks
Doug

[masahiraoka]

Neils
the cylinders are printed in plastic and used as a pattern for casting. Naturally the plastic pattern is lost in the process.
the brackets are printed directly in stainless steel. There will be photos of these in coming posts.

Doug 
similarly there will be photos of the raw castings of the cylinders coming shortly. We haven’t yet machined these but they should present no particular problems doing so.

regards Martyn 

[masahiraoka]

• As one member of this forum has said else where doing these detailed CAD designs is very time intensive.

• As of the middle of March 2020, Phil has spent 6,000 hrs on the project with the chassis essentially complete.

• Approx. 20% of his time has been spent on sourcing suppliers, refining the manufacturing techniques and modifying the CAD design accordingly.

• complex parts e.g. brackets and stretchers are being 3D printed in 316L or 15-5PH stainless steel.

• We're still working on the trade-off between cost, machinability and finish quality for the two steels.

• 316L (yield stress 460MPa vs mild steel 250-350) is not as hard/stiff as 15-5PH (950MPa).

• Flat parts, e.g. the frames, are water jet cut with tab and slot design for suitable slightly more complex parts e.g. bogie bracket stretcher and front stretcher (in front of leading coupled wheels).

• Large “solid” parts e.g. cylinders are cast in silicon bronze from patterns 3D printed in PLA plastic.

• The best guess for the time required to complete the rebuilt West Country design, production engineering and construction of the prototype is between 3,000-4,000 hrs, suggesting a total time of 9,000-10,000 hrs.

• The next seven Posts will show the detailed design and printing of important brackets, stretchers, the cylinder castings, wheels and reversing gear cab gear box.

• Following these I'll post a series of detailed screen shots of the chassis and engine in gradually increasing levels of assembly.

• Finally there will be a series of posts that document the assembly and completion of the prototype locomotive

[Cro]

Be careful with 3D printed stainless, metals in general, as they are extremely difficult to machine as the sintering process makes them very hard. You would be better off printing in a wax (PLA is ok but you won’t ever get as fine detail in places) and casting in a white bronze which has 4x strength of a silicone bronze.

You also get a much more reliable burn out with wax than with PLA I have found. The beauty of the wax is you need very little machining allowance and typically geometrically they are very stable.

Whichever route you choose for printing, especially in small sizes such as these, be very careful about the cast in passageways and ports. If you have long passageways I would suggest looking at plugs somewhere along the way that you cast separately and solder in this way you can a much better clean out of support materials, more support in the mould and all round more reliable casting throughout the process, this is something Mike and I have adopted even in large 7 1/4” castings.

I will try pop some photos up later to show some examples of the above to make it clearer.

Hope this help,
Adam