Stanier 8F 2-8-0
Recently, I was fortunate to be given a number of completed Alan Gibson LMS and Midland Railway locomotives. Although nicely built they aren't all suitable for operation on the sharp curves of Halifax Midland so, in some cases, a partial rebuild will be necessary.
The first to be tackled was the Stanier 8F, one of my favourite classes. Perhaps this isn't so surprising as I saw 485 of the class in my travels around northern England in the 1950s and 1960s.
The model, as originally completed was powered by a Portescap motor and gearbox and was clearly very powerful. However, it struggled with the curves on Halifax and also suffered from the problem of the return crank not being rigidly fixed on the crankpin. This resulted in the valve gear performing some very strange antics.
Eventually, I decided on a partial rebuild. Firstly, I constructed a powered tender as described on this page. Having proved the concept I decided to remove the motor. This necessitated dismantling parts of the valve gear, connecting and coupling rods and removing the rear three axles. The loose connecting rods and return crank assemblies were temporarily held out of the way, by wrapping some fine wire around them and securing them at the top of the chassis.
In an attempt to overcome the problem of rotating return cranks I decided on a somewhat drastic solution. I had used Romford crankpins for many of my 4mm scale locomotives, and had found them robust and simple to use. Best of all the return cranks were soldered firmly in place on the crankpin. I therefore decided to replace the Gibson crankpins with Romford ones; it was a surprisingly easy task.
The Alan Gibson crankpins were unscrewed from their holes and these were then opened up a little at a time using fine tapered broaches. When I judge the holes were just about capable of having the screw of the Romford crankpin inserted, I gripped the shaft of the pin with pliers and gently screwed them into the hole. The screw cuts a thread into the plastic but it's essential that the crankpin is at right angles to the wheel as you do this. From the effort needed to do this I was pretty certain that they wouldn't come undone in use. However, I then unscrewed them a few turns and put a drop of Loctite on the thread and then quickly re- tightened the crankpin.
Once all six of the rear wheels were converted, it was a relatively simple matter to re-quarter the wheels. I did this using a mirror behind the model, allowing me to see that the crankpins are set at 90 degrees to each other. The coupling (which had all been hanging loosely from the undisturbed front wheels) and the connecting rods were then put back on the crankpins and the chassis test rolled. Once satisfied all was well the little securing washers, that come with Romford crankpins, were soldered in place. The return crank was then soldered in place in the correct position.
For once, very little tweaking was necessary and the free rolling chassis happily rolled around the tightest curve on the layout - a flange squealing 36" radius. I hasten to add this loco is not going to be expected to cope with this sort of curvature on a regular basis, but it shows what is possible.
As the tender is a completely self-contained unit, all that is needed is a simple loop and hook coupling between locomotive and tender. The tender seems quite happy picking up current on just four wheels so, unless matters change, the locomotive itself won't be fitted with pick ups.
The haulage capabilities of the model are more than sufficient for my purposes as it happily lugs all 30 of my wagons, most of which are heavy cast metal models, around the layout.
The photo below shows the completed loco.