It’s the little things which can make a big difference. Incidentally this is a good statement to make in some more personal situations too if you’re feeling a little inadequate too.
Couplings on locomotives are a good example of this – a small detail but get it right and the whole is much better for it. In fact you’re likely to notice a horrible, chunky, overscale screw coupling than a nicely proportioned one. I wince when I see a beautiful, kit built loco which has had a set of those massive Romford screw couplings. They look appalling in 4mm scale – though, in S Scale, the look pretty good!
Personally I really like the lost wax, cast brass couplings from Alan Gibson. They look superb and the ‘Heavy Duty’ type is perfect for most mainline diesel classes. These are best regarded as cosmetic though – not a problem as we’ll be using Spratt & Winkle couplings. You can make these work, but the hooks are very much to scale and, as such, operation will be very fiddly and awkward. If you want fine but working couplings then the Masokits screw coupling is a very good option. Paul Marshall-Potter has written a great guide to assembling these and using them.
The coupling comes as a brass sprue from which the individual components must be removed. Before this though, the holes in the links need to be drilled out to 0,5mm diameter – this matches the size of the pins on the centre section.
There’s more than one way to remove the individual pieces – you could use a slitting disc in a mini-drill if you were confident, but there’s little room for error (guess how I know this!). Side cutters also work but leave you with a good deal of cleaning up as you can’t cut too close without risking deforming the parts. My now preferred method now is to use a piercing saw to cut the parts off. You can a lot of control and can get very close to the parts leaving very little cleaning up required. Once you’re happy with the appearance of the parts, the holes need to be opened up to a running fit on their pins. Using a small cutting broach the holes need only a tiny amount of material removing.
Assembling should now be quite straightforward – small pliers will allow you to bend parts slightly to fit and then align everything. The links only need a slight tweak to allow them to fit on the centre section. One both links are in place the top link needs to be ‘popped’ into place through the top slot in the coupling hook. Fine nose pliers are a good way of doing this. If you’ve done this before, it may sound daunting but the cast brass has a bit of flexibility and as long as you don’t keep doing it, it won’t adversely affect the pieces.
Once the couplings are together I blacken them in Birchward Casey ‘Super Blue’ gun blue which works very well on brass. Within a few seconds the appearance will darken and within thirty seconds they are ready. The Super Blue gives the brass a lovely dull finish, but if you gently rub either a finger or cotton bud over the surface it’ll buff to give a wonderful oily sheen.
As these are purely cosmetic I simply glued the shank of the coupling hook in place – when I have used them in the past functionally I have pinned them in place, having drilled a hole in the shank for this purpose.
It takes between half an hour and an hour to assemble a pair – it depends how confident you are or whether or not you have done a pair before. And once you’ve done one, the next is much easier! I think they are well worth the effort – the photo of them fitted to 20104, below, shows the final appearance.