Model of an LMS Black Five Loco Front Bogie for Gauge 1. (1 3/4″ or 45 mm Gauge)

Photos of a Gauge 1 (3/8″ scale) Black Five Locomotive bogie based on LBSC’s 3 1/2″ gauge  (3/4″ scale) “Doris” plus related documents.

It’s based on the 3 1/2″ gauge (3/4″ scale) LMS Black 5 Engine “Doris” as designed by LBSC but I scaled it down to half that size.

What Is A Black Five And Who Is “Doris”?

Well, I can’t expect everyone to know these things, but here is the answer:-

“Doris” is the name given to a model steam locomotive designed by the late and great “LBSC”. The model is based on the LMS Stanier 4-6-0 Class 5 loco introduced by William Stanier in 1934.

“Doris” is designed to run on tracks of 3.5″ gauge and is to a scale of 3/4″ to one foot.

And Who Is Dot?

“Dot” is again and LBSC designed model loco of the same prototype but is half the scale of “Doris” at 3/8″ to the foot and runs on tracks of 1 3/4″ gauge. This is known as gauge One, or G1.

So What Is a Bogie And Is it “Doris” Or “Dot” You Are Building?

At the time I wanted to build the complete engine but part-way through the bogie construction was as far as i got.

This photo shows the bogie on Doris:-

Limited Workshop Facilities

At the time (1993) my ‘workshop’ was in an upstairs boxroom and basically comprised just a small lathe called a Minilor TR-1.

The Minilor TR-1 Lathe was made in France and sold in the UK in the early 90’s by Hegner UK Ltd. A Milling head was available called the FR1 In many ways it was similar to the Emco Compact 5 but the Minilor was made from cheaper materials and not to the same standard as the Compact Five. The price was a fraction of the Emco lathe but just couldn’t perform.

The Minilor TR-1 Lathe was 65 mm centre height and about 350 mm between centres. Here is a photo of what’s left of it today. (2015)

By the way that lathe has been re-purposed and is currently on the cross slide of my big Kinwa lathe acting as a very effective spherical turning attachment.

I wanted to build the larger 3 1/2″ gauge Doris but due to limited facilities it had to be Dot.

“Doris” Detail At A “Dot” Size

The “Dot” design was a very much simplified version of “Doris”. “Doris” has external valve gear which is entirely omitted on Dot. See the photo where I have marked up the valve gear on Doris – those bright flashy steel rods:-

I just had to have this external valve gear on my model so I tried to copy it from Doris. (More on this later)

Also for example the Dot bogie was a very simple affair lacking much of Doris’s detail so I decided to scale down and model the Doris Bogie.

I was aiming for a model with Doris’s detail at a Dot size.

Other Related Content On This Web page

Also shown are various purchased drawings of the 3 1/2″ gauge LBSC’s “Doris” and his Gauge 1 version “Dot”. There are also the CAD drawings I made at the time and various other related documents and a photo of the lathe I used to make the model on.

I made this model in 1993, some 22 years ago. Being 22 years old and simply kept in a tin box as I moved house several times, the model has suffered from rust and a few parts have fallen off.

The model really is tiny and the photos are deceptive. Because of the fine detail of the model it looks bigger than it actually is.

This page is not just a few photos of a model. It illustrates my approach to model engineering 22 years ago and which has changed little since then. It also proves that I can make small models not just half sized traction engines.

Photos Of the Gauge One Black Five Bogie

Images Of The Drawings Used To Make the Model

First, here is the main CAD drawing I made:-

LBSC’s Doris is a design for model Stanier Black five for 3 1/2″ gauge. I scaled down his Doris bogie drawing and simplified it to suit Gauge 1. (1 3/4″ gauge)

And here is a detail from that drawing showing the axle springing arrangement:-

The scan above is a close-up of my CAD Drawing of the Gauge 1 Black Five Bogie showing the springing detail.

Note the tiny size of some of the screws, 14 BA for the Axle Box Keep for example. 14 BA is 1 mm diameter and the tapping drill is 0.82 mm (No. 66)

It is important to get the wheel tyre profile correct to G1 Standards. This CAD drawing shows me adding the wheel profile angles.

Part of the General Arrangement drawing of the Gauge One Stanier Black Five Loco model designed by LBSC. The lack of outside valve gear is noticeable.

This is a CAD drawing I made for the equalisers for the Gauge one version of LBSC’s 3 1/12″ Gauge “Doris”. It is based on the Doris drawing but scaled down to suit Gauge 1.

Before making a CAD drawing some key dimensions need to be established. This is a sketch I made to determine the critical setting out dimensions of the wheels and frames for the Gauge One Black Five model loco.

The original drawing by LBSC of the bogie for his 3 1/2″ Gauge LMS Stanier Black Five Loco. You can see where I have marked up the drawing with metric dimensions at half size to suit 1 3/4″ Gauge (G1).

Piston Valves And Green Arrow

Although I only ever made the bogie of the Black Five my intention at the time was to make the complete locomotive and whilst building the bogies I was looking forward to other aspects of the LBSC Dot design that needed amending.

One of these was the external Walchaersts valvegear which as I have explained was non-existent on Dot.

Dot’s bigger sister, Doris had external Walchaersts valvegear but also had piston valves which I thought would be impracticable if scaled down to gauge 1. The piston valves were far to fiddly for a 3/8″ scale model.

LBSC’s own drawing of the cylinder and piston valve assembly for his 3.5 inch gauge Black Five “Doris”.

Getting a gas-tight seal between the piston valve itself and the piston valve bore would be a major challenge in Gauge 1.

The valve gear on the Gauge 1 steam loco model of green Arrow designed by Martin Evans is full Walschaerts outside valve gear. I was interested to incorporate it into my Gauge 1 Black Five model. preliminary investigations suggested that it was entirely feasible.