Metalworking

This is the part I’ve really been dreading. I want to keep the platform because it gives the model a nice, rigid base and has some useful detail I can make use of. On the other hand, diecast metal is a horrible material to work with. The stuff is hard, brittle and unforgiving. Cuts are final, scratches are difficult to remove and pieces snap off easily never to be reinstated securely. So, understandably modifying this part is something I’ve been holding off, meanwhile measuring carefully and then measuring again.

Remarkably, my little Y9 shunter is actually bigger than FR 20 in almost every respect, not least its length. I have already decided to retain its original wheelbase despite being 2mm, or a scale 6 inches, longer than FR 20. So the plan is to leave the centre section untouched and consequently the springs in the right places relative to the wheels. That means any length adjustments will be restricted to the area between the wheel centres and the buffer beams. I intend to make those distances accurate meaning that the overall length will be plus 2mm due to the wheelbase.

To help make accurate, square cuts, I made myself a dedicated 00 scale cutting jig. It simply comprises three pieces of wood screwed together in a U shape and with some accurate guide slots cut across it. The last part was the big challenge. I know all about a bad workman blaming his tools and all that but I had made two neatly curving saw cuts before I realized that my tennon saw naturally cuts curves. In the end I managed a straight cut using a hacksaw.

At the rear, the mod was easy enough. When measured, the cut line fell neatly along the mould line denoting the front of the buffer beam. I cut upwards from underneath and using my jig achieved a nice square cleave. It also conveniently took the rear rail off with it; which was a bonus. Obviously FR 20 is a tender loco, so will not need buffers at the rear but more of that later.

With the cut made, the exposed surface revealed just how horrible these castings are. Granted, this was one of the thickest parts of the casting, but it revealed huge great voids in the metal. A lesson for the future when working with these parts is not to assume they are homogenous.

Packaging problem

FR 20 approaches Mytholmes tunnel
[image courtesy of Furness Railway Trust]

Perhaps this project’s biggest challenge is squeezing a standard-sized motor into a boiler slim enough to look plausible. As you can see from the pictures, FR 20 has a boiler that is much narrower than the engine making it very hard to find somewhere to put the motor. In contrast, the Y9 has a generous amount of space inside its ample water tank to accommodate the power unit.

For my project I don’t expect to be able stick to the dimensions of FR 20 down to the millimetre, but the closer I can get to them, the more convincing the model will look. Nothing will spoil the illusion more than an incongruously large boiler. In fact, thanks to the size of my intended smokebox, which I’ll come to later, the largest diameter I can take the boiler out to is 19mm. However, the width of the motor is 20mm and simply will not fit.

What are the alternatives? A smaller motor is a possibility if I can find one that delivers similar power from a more compact package. However, before I set off trawling the internet for a possible candidate, I wanted to try another strategy.

The end profile of the motor is circular with flats on the top and bottom slimming the height down 16mm. If I could turn the motor through 90 degrees, it would effectively narrow the width of the motor and the top half would fit into the boiler while the rest could be buried out of sight in the chassis. But would it work?

I tried measuring the clearances, between the wheels and under the intended line of boiler top but couldn’t be sure. This is a game where half a millimeter counts and the only way to be certain is to try it and see.

I chamfered the sides of the chassis to find a little more space, but the big adjustment needed was going to be the mounting block. I had to file 2.5mm off the deck the motor sits on and hope for the best. Working slowly, measuring and test fitting again and again I eventually gained enough space for the motor to sit on its side.

But would it fit in the chassis, stay clear of the wheels and not sit too high? I assembled it all with trembling fingers wondering whether I had made a big step forward or just written off a previously operational loco. And the result? Success! It not only cleared the wheels by a good half mill, but it also will only raise the boiler height by one millimeter over the scale height of real thing. Phew!

The cutting begins

The tank loco is quite old and it turns out the ends of the more recent Y9’s axles are smaller. So a straightforward swap of the wheels is not possible. However, the main axles are the same diameter on both engines and as long as I use the whole assembly from the older loco, they will fit into the Y9’s bearing.

The bigger wheels do foul the Y9 chassis in a couple of places, though, most notably the brake blocks. But with a bit of work with a modeling knife they are dispensed with and the wheels fit snuggly up against the chassis.

I also plan to reuse the platform as it comes with several benefits. Cast in metal it’s solid and heavy which will aid traction. Plus it comes with some nice detail like the springs that are in the right place for FR 20. But when added to the chassis with its new wheels they foul. Fortunately, the interference is very small and hopefully a little grinding should create the necessary clearance.