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Designed and built in the workshop here, we conceived "Stafford" as a robustly-engineered, easy to drive locomotive - something equally at home on a garden railway or public running at the local club. 

Having worked on some hundreds of locomotives over the years, a lot of the design choices fell into place easily: 

• An all-welded steel boiler with replaceable tubes - easy to service and maintain, with the ability to run at 120psi making for easy steaming and a good reserve of power
  
  

• Full-sized controls - the regulator, reverser, steam and water valves are built to fit a driver's hand, they aren't scale versions which are difficult to get hold of and, when you do, are discovered to be red hot!
  
  

• Steel wheels. Cast iron wheels + steel rails = grooves in the treads - in the first season on my Tinkerbell (admittedly running a commercial service), which needed tyres at less than a year old. In contrast, the wheels on our demonstrator engine still look pretty much the way they left the lathe
  
  

• Sealed ball-bearing axleboxes, which reduce maintenance, increase service life (by keeping grit out of the bearings) and ensure that as much power as possible gets to the drawbar, rather than ending up being used to overcome rolling resistance.
  
  

• Walschaert's gear for it's accurate control of  the valves over a wide range of cutoffs - this allowed us to set out the gear to give generous full-gear cutoff for reliable starting (and I've lost count of how many big engines I've driven that need a bit of driver's leg assistance to move away after stopping on a "dead spot" in the valve gear) whilst still allowing economic high speed running with the lever "notched up"
  
  

• Cast iron cylinders with slide valves. Pistons are in iron, fitted with the incomparable Clupet rings
  
  

• TIG-welded stainless steel water  tank. I can't remember how many grotty old rust-filled tanks we've cleaned out and repaired on other engines over the years (usually they either start leaking or shedding rust into the injectors, both if you're unlucky) - Stafford's tank is welded, pressure tested then passivated to prevent corrosion at the welds before priming with an acid-etch and spraying in two pack paint.
  
  

• Ball valve regulator - as fitted to my Tinkerbell in 2002 and still going strong (not to mention just about every other successful commercially-built locomotive of the last ten years). Silky smooth in operation, light action even under high working pressures, absolutely steam tight and easy to replace should the need ever arise
  

The engine has been designed in SolidWorks, allowing us to test assemble and simulate the motion of all parts before transferring them to our CNC machines to cut metal. The valve gear was calculated from first principles before extensive simulation to check accuracy and symmetry of valve events at all cutoffs.

Frequently asked questions

Having talked to a lot of people during the development and testing of "Stafford" over the last twelve months, both at shows and in the workshop, some questions come up again and again:

• Does the engine come with a boiler certificate?
  
  Yes. We have a commercial boilermaker build our boilers in batches - they are CE-marked and come complete with the maker's twice working pressure hydraulic test certificate. Prior to despatch, our boiler inspector visits to see the engine in steam and checks operation of the safety valve and injectors. The engine is then issued with a new boiler certificate. Subsequent testing can either be done by a commercial inspector - this involves an internal inspection and steam test annually with hydraulic test every 7-10 years - or your local model engineering club, who will steam test each year, with a hydraulic test after the boiler is four years old, then every two years thereafter.
  
  

• I'm a complete beginner - would I be able to drive and look after the engine?
  
  Absolutely. The engine comes with a comprehensive set of operating & maintenance instructions which cover everything from unpacking the engine when it first arrives to dropping the fire at the end of a day's running. Having taught people to drive everything from a 2 1/2 inch gauge "Dyak" to a 7 1/4 inch gauge Baldwin K36 over the years, there aren't many problems we haven't come across! Anything that isn't covered in the manual, we're only ever an email or phone call away.
  
  

• Is it possible to see an engine running?
  
  Of course. Check to see if our demonstrator is here at the moment (it normally is, although it sometimes goes out on loan to individuals or clubs) - if it is, you're welcome to come and have a drive on our test track. In addition, there are some clips of the engine running on our YouTube channel here:
  
  Club running day at Evergreens Miniature Railway, September 2009
  Prototype running on air in the workshop

  

  Demonstrator running at the National Railway Museum over half term, March 2011 - some words and a video of it working hard here

  
  Our demonstrator is the first engine completed from the original batch of four we built to prove the design. It's done nearly 1000 miles now, either at my own club or out on loan - it went to the Midlands Model Engineer Exhibition in October where it ran up and down for five days giving a variety of people rides (or drives for the more adventurous) - there's a page all about this engine here.
  
  

• Is the engine available as a machined kit?
  
  No. I'm not a believer in kits for a variety of reasons. The "stage a month, pay as you go" kit build market in the UK has had a far from happy history over the last ten years - too often ill-conceived and untested designs have ended up on sale which, in the end, has only led to disappointed (not to say out of pocket) customers. Whilst it is desirable from a manufacturer's point of view to have a regular payment every month whilst an engine is being built (it pays the wages and buys material), the advantage to the customer is far from obvious.
  
  Having said all of that, there are well-run, reputable companies who produce kit-build engines and have done so for years (and, if you look on the archive of this website, you will see many examples that we have sold over the years and been most impressed by) - we salute them, it's just not what we want to do.
  
  What we can supply is a "fast build project" - a complete set of drawings, castings, boiler, saddle tank, all laser cut parts and fittings. We estimate this would enable the average model engineer with lathe and milling machine to produce a finished engine in about a third the time one would expect to build from scratch - see the full listing to decide if this is the way to go for you.
  
  

• Will I be able to get spares in the future?
  
  Yes. We keep most of the "service" type spares (bushes, valves, etc) in stock on the shelf. The remainder can be manufactured rapidly using the original  fixtures and programs used to build the engine.
  
  

• Is it guaranteed?
  
  Yes. The engine is guaranteed for 12 months against defects in manufacture. Just like our secondhand engine policy, I like to think it's a "no quibble" arrangement, the design is intended to provide a reliable, easy to service piece of machinery which will give good service for many years if looked after sensibly.
  
  

• How do I order a "Stafford"
  
  Ring us up and ask! We're currently on an 8-10 week delivery schedule, although with the completion of the next batch of engines we hope to get that down delivery ex-stock for the standard engine and 2-3 weeks for one needing optional equipment (including a non-standard colour). There is a deposit of £250, for which you will be given a receipt, your engine's works number and expected delivery date.
  
  

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