Constructing Siusaidh - a large 7.25" gauge engine

Running dates
Siusaidh will be visiting the Moors Valley Railway on 1st May 2010 for their Tinkerbell rally

Something you won't find anywhere else on this website - a picture of me!! I'm the ugly old one leaning on the cab, by the way. This photo was taken on her first day of serious work at the SNBR. Lining and numbering still to do, but the end of the road is VERY close now. There were a couple of minor niggles, all easily sorted out, and, apart from that, she did a very good 7 miles on her first day out.

This page documents the construction of a LARGE Tinkerbell style engine. This started out as a locomotive close to the original (Roger Marsh) drawings, but ended up as something a lot bigger. Follow this link for the full story, from what I started building to what I am now building.

This link takes you to a page with some pictures of Jason at the Moors Valley Railway, the inspiration behind this project.


This table summarizes progress to date. From the start of 2006, I will attempt to update it monthly. Click on the photos to see a larger version.

January 2008

  • Make and pipe up vacuum ejector
  • Fit cab beading and rain strips to cab
  • Make and fit chimney liner and spark arrestor

    Total: 22 hours work

  • Just before Xmas 2007

  • Pictures of her first and third steaming: Not all brilliant quality, I'm afraid, bit I was smiling too much to care. . . . .
  • Raising steam

    Under power at last

    After her boiler test at the SNBR (Thanks to John Downes for this photo) - and me in the cab at last !!

    November 2007

  • Fit chimney
  • Make and fit gauge glass blowdowns
  • Make and fit regulator stand
  • Make and fit grates
  • Make and fit blast pipe nozzles
  • Remove tanks and undercoat

    Total: 37 hours work
    Just a few jobs to go before she's steamable, we've provisionaloly booked the boiler tester just before xmas (Fingers crossed)

  • October 2007

  • Complete welding up cab
  • Make and fit bunker coal rails
  • Seal tanks
  • Make and fit firehole door

    Total: 38 hours work

  • September 2007

    At last! The boiler's on !! Tanks nearly done, started on the cab. The photo shows the engine in early October. The rear of the cab is welded up, the front is just clamped on, and the roof is just placed on. But she looks the part !!
  • Make RHS tank
  • Fit tank water valves
  • Fit blowdown actuators
  • Start welding up cab

    Total: 38 hours work

  • July/August 2007

    Went to the Severn Valley Railway to roll the smokebox and other curved bits, then made up the smokebox. With this fitted to the frames she really does start to look like an engine at last - probably more so than at any time in the past !!
  • Make LHS tank
  • Make smokebox
  • Start fitting chimney

    Total: 50 hours work (Over 2 months - and passed 700 hours on the project)

  • Boiler on, chimney, dome and tank placed on: looking like a locomotive at last.

    June 2007

  • Continue chime whistle
  • Make MVR style coupling
  • Mill and lap vacuum control
  • Complete smokebox dart

    Total: 16 hours work


    May 2007

  • Make and fit firebox supports
  • Fit second smokebox support
  • Fit ashpan
  • Adjust RHS expansion link position
  • Air test on large compressor

    Total: 26 hours work


    April 2007

  • Run vacuum pipe through, make standpipes, continue work on the drivers valve
  • Complete ashpan
  • Start work on smokebox door and closing apparatus

    Total: 15 hours work
    The boiler has arrived !!!


    March 2007

  • Make remainder of drain cocks and fit
  • Fit running boards
  • Form ashpan
  • Start to fit vacuum piping and stands
    Total: 21 hours work(Also passed the magic 600 hours on the project)


    February 2007

    First air test (on a small compressor) done, makers plates arrived

  • Remedial work from air test
  • Cut out ashpan
  • Start boring out chimney cap
  • Make first drain cock
    Total: 24 hours work


    January 2007

    Several 'little' jobs done, so not much to show for the work but much closer to air testing. Ordered the makers plates.

    Build lubricator and fit

    Fit steam pipes

    Shorten rear brake hangers to make ashpan simpler to make

    Mock up ashpan (in card)

    Total: 26 hours work

    Makers plate, in negative form, ready for etching


    Motion complete, lubricator piped up, in forward gear. Ashpan micked up in card.

    December 2006

    The festive season meant that I didn't get as much time as I might have liked to work on the engine, but, as 2006 closed, I had a chassis which was ready for air testing apart from the LHS eccentric rod which needs welding and the lubricator needs completing.

    Make and fit LHS motion pins

    Calculate and make LHS eccentric rod

    Fix reverser stand

    Cut reverser reach rod to size

    Start on lubricator

    Total: 15 hours work


    November 2006

    Get RHS eccentric rod re-welded and ground back

    Make and fit final RHS motion pins

    Complete reverser catch and handle

    Fit LHS piston rings, pin piston rod to crosshead

    Cut and fit first section of footplate

    Start making lubricator tank

    Total: 26 hours work


    October 2006

    Fit RHS Trunnion hangers

    Shorten and turn down valve rod tails

    Trim backs of combination levers

    Make new union links

    Make new eccentric rod forks (More offset towards centre of loco)

    Fit 2 weighshaft arms

    Fit RHS piston rings, pin piston rod to crosshead

    Trial assemble RHS valve gear. Eccentric rod 5mm too short

    Grind off eccentric rod fork, clamp and check

    Make RHS return crank

    Mill out reverser handle

    Total: 36 hours work
    Note for anyone building their own design of Walschaerts valve gear: the gear is very sensitive to the length of the eccentric rod (have a play with Charlie Dockstader's simulation to see this). However well you design and build the gear, the length of this rod is critical and won't be what you expected !! It is essential for good valve openings that the expansion link swings excatly the same amount fore and aft of its centreline. So, calculate where that centreline is and find an easy way of measuring it (I measured from the motion plate). Now, assemble all the valve gear (but leave the eccentric rod adjustable length, e.g. clamp the fork on the end rather than weld it) and measure the swing. Adjust the fork position until it is correct. In the picture, I've adjusted it and it waits re-welding and dressing. The drop links are also temporary ones for checking.

    RHS motion trial assembled, in forward gear !!

    September 2006

    Bore out and fit connecting rod big end bearings

    Make little end pins

    Fit Left hand motion bracket

    Fit and align slidebars

    Make and fit valve rod tail supports

    Make jig and turn eccentric rod end caps

    Make and fit valve straps

    Fit right hand valve

    Test fit both connecting rods

    Total: 40 hours work

    Motion plate, slidebars and conn rods fitted !!

    August 2006

    Make and fit piston rods

    Machine rear cylinder covers and all glands

    Fit parkside speedo sender unit, refit rear bogie

    Make cylinder gaskets

    Wash out cylinders, fit to frames

    Fit coupling rods

    Fit front smokebox support

    Make valve rods and tails

    Bore out trunnion hanger brackets

    Make return cranks

    Complete milling out of crossheads, fit union link hangers

    Total: 60 hours work

    July 2006

    Complete brakes

    Complete and test front pony

    Fit cycle speedo

    Total: 19 hours work


    June 2006

    Complete new front pony - just needs rubbing plate in frames to complete

    Bore out and fit bearings to coupling rods

    Fit reverser bracket to frame

    Total: 20 hours work
    New pony built and ready to go. Coupling rods ready to fit. Laser cut smokebox supports, front footplate filler etc. arrived.


    May 2006

    Turn new front pony wheels

    Order new front pony frames

    Fit driving wheel spring hangers

    Make brake actuating rods and cross beams

    Machine first slide valve

    Total: 20 hours work
    Having sprung the drivers, stability was much better, but the extra stability gained by the outside-framed pony was still considered worthwhile.


    April 2006

    Make and fit brake shaft bushes

    Fit footwell angles and floor

    Cut and fit reverser stand angle

    Cut and fit brake hangers

    Drill and tap cylinder front covers

    Drill and tap left hand steamchest fitting bolts

    Rough out pistons

    Grind port faces flat

    Total: 20 hours work
    Tests showed that with the original inside-framed front pony, stability was not as good as it could have been, especially on tight curves. In order to accomodate an outside framed pony, the wheels would have to be made smaller, and new side frames ordered.


    March 2006

    Fit rear bogie

    Mill out cylinder ports

    Drill steam passages (from ports down to the bore)

    Mill out steamchest to size

    Mill steamchest covers to size

    Drill and tap right hand steamchest fitting bolts

    Total: 30 hours work


    February 2006

    Bore and face cylinder blocks. Top photo shows the right hand block being bored, having already had the mounting and valve faces machined flat, and the exhaust outlet drilled and tapped.

    Face steam chests

    Paint flycranks

    Join frames together. The bottom photo shows them after fixing, the smokebox supports are just put in place to show how they will fit. Some footplate and firebox support angles also bolted in place. (Note: Chalk marks in the picture are where the frames were straightened. As delivered, there was a slight bend at the front of the frames)

    Total: 31 hours work

    January 2006

    Drill frames

    Make spring hanger welding jig

    Mill connecting rod small ends

    Fit horncheeks and axlebox retainers

    Total: 31 hours work


    December 2005

    Laser cut frames, buffer beams, coupling and connecting rods arrived. Photo shows one frame posed with the wheels (and a lot of leaves)

    Summer 2005

    All valve gear and motion forks, trunnion blocks, drop link hangers, crossheads and combination levers milled from solid. Picture shows some of these fitted to rods, and the whole lot laid out to show how it will all fit together

    Early 2005

    Tinkerbell trailing truck turned round to be used as leading truck. This may require wider wheels making to suit "Haylock gauge" as the ones currently fitted are from 25mm thick blanks.

    Drivers machined from 35mm thick blanks, fly cranks and crankpins machined, assembled and quartered.

    Rear truck wheels manufactured from 28mm thick blanks, truck laser cut and built

    Both trucks use ball transfer units on the contact surfaces. Sacrificial rubbing plates are to be employed for when/if wear gets unacceptable.