At Expo EM Bracknell 2019 I got to talking with Karl Crowther, a professional model maker whom I am sure is known to many S4 modellers. He had been commissioned to convert the then recently released Bachmann GN Atlantic to S4 and was contemplating scratch building a chassis for it. I at the same time was thinking of converting the same (or was it?) to EM but in contrast I was planning to scratch build my chassis on the computer to effectively create a kit. I therefore undertook to provide Karl with an S4 option of the etches once I had successfully test built my model in EM and in return his customer would help out with the cost of development.
in June of 2020 and on the 2nd attempt, I successfully completed my test build to create this model in EM:
It was then over to Karl to have a go at building the S4 chassis. It was a couple of weeks into the build that he hit a particular problem with the tender. It transpired that in the period from our initial agreement to the point of my delivering the etches to Karl, Bachman had re-released the model with a different tender. This alternate tender was fitted to the preserved loco (GNR No. 272) when it was first built and had a completely different wheel and brake arrangement.
It was back to the drawing board for me and my CAD design was updated to allow either tender variant to be modelled. In order to ensure that the re-design was successful I ended up building this model in S4:
The loco’s frames are compensated: twin beams on the driving wheels and the third ‘leg’ of the compensation is a pin directly above the rear bogie wheel around which the bogie pivots. In the raw the chassis looks like this:
The tender in contrast uses CSB instead of compensation. Three tender variants can now be built using the etches: the original Bachman tender with the offset wheelbase, the revised tender with the equally spaced wheelbase and the brakes to the front of the wheels, and a third variant using the body from the re-released version known as a horse shoe tender having the brake hangers traditionally placed behind the wheels. The revised tender chassis in its ‘front ender’ form looks like this:
I have a small stock of etches (only) which I am prepared to make available to members of the S4 and EM Societies. Anyone wishing to acquire a set of etches can contact me by email: frank.davies@btinternet.com