Lilla – An 0-4-0 Narrow Gauge Loco in 7 1/4″ gauge.

I started this project a few years ago and due to other commitments and projects Lilla’s build stalled.

Lilla is just over 58 ins. long and the buffer beams are just over 21 ins. wide with 7 1/2 ins dia. wheels. Cylinders are 2 1/2 ins. bore with a 4 ins. stroke.

The current COVID-19 situation has lead to more time in the workshop so a bit more progress has been made.

Lilla from catalogue a

Painting the frames with etch primer.


The first of several coats of red on the frames.


The copper boiler is a big beast. A hydraulic test confirmed all is well and ready for the fittings to be made.


I had a problem with the eccentrics – the straps kept moving sideways. So I modified the eccentrics to have two walls / sides instead of one. Much better.

Lilla valve gear 1

Showing more detail of the modification to the eccentrics.

Lilla eccentrics 2 a

Modification to the eccentrics completed.

Lilla eccentrics 1 a

Detail of the expansion links.

Lilla valve gear

I have spent the last few days pushing Lilla back and forth on its building stand track which is exactly one wheel revolution long. It is quite stiff.  I have clearly identified it to be the cylinders need wearing in.  I have kept a tally of 6900 revolutions or pushes… but it is much easier and I think the cylinders are nicely polished / worn in.  Time to try it on compressed air. Cross fingers!

This short video shows her working at approx 20 p.s.i.  supplied from two separate compressors.  It is not quite as smooth as I would like so the plan is to tweak one of the eccentrics a very small amount before locking them in final position.

9 Drain Cock Drawing

After getting the valve gear working as well as I could it was on towards a fully completed running and painted chassis.  Next were the four drain cocks. Not your usual turned up ones – a little bit of fabrication and silver soldering was needed.

10 Drain Cocks taper reamer

Boring out the tapered holes on the drain cock bodies. Each body started life as a 1 3/4″ length of 1″ square brass with the threaded end turned first.

11 Drain Cocks parts

This shows from top right:- machined and hardened taper reamer, three part finished bodies and finally top left a finished body.  The square brass in the middle is  for a short piece silver soldered into the body as a steam outlet.

12 Drain Cocks parts

A finished drain cock. Taper cock in stainless steel. I was lucky to find a 1/4″ square broach which made the cutting of the square hole in the levers very quick and easy.

13 Draincocks

A finished drain cock in situ. I decided to make all the pins in the levers from stainless steel silver soldered to mild steel levers.  All nuts and washers and spring washers are also in stainless.

14 Using the Reglus holes fo taper pins

The Reglus drill jig in use again.  This time drilling for all the taper pins in the drain cock levers and linkages.

15 Draincock levers

Drain cock levers and linkages almost complete.

16 Draincocks 2

Drain cocks finished – levers and linkages ready for painting.

I deliberately silver soldered the steam outlets so that they point approx 22 degrees out to the side in order to avoid the buffer beam.

Regulator 1a

I have decided to use a stainless steel commercial ball valve for the regulator.  A significant number of builders appear to praise them so we will see. The mounting pillar was an “interesting” fabrication all silver soldered up. The tube-plate and the back-head are not quite 100% parallel to each other so I made a tapered washer to pull the main regulator shaft across a little.

Regulator 2a

The ball valves are PTFE sleeved and some are rated at approx 180 C.


Regulator 3a

Completed assembly.


Regulator 4a

Checking the completed assembly before bending the split pins.

30 smokebox elbow 1a

Above – set up for machining 45 degree angle for smokebox elbow.

31 smokebox elbow 2a

Above shows both halves machined and ready for a little fettling and silver soldering. I used a saw cut to insert a small piece of brass to hold the two halves inline.

32 smokebox elbow 3a

The completed elbow after silver soldering. The piece of brass is then filed away and a small radius will remove all signs of the corner piece.