Illustration by the author

If you are having difficulty coupling up screw couplings then perhaps you might be interested in a solution that I have tried with success. The materials needed are simple and cheap and easily available. You will need to have a 10BA brass cheesehead screw and nut, a cocktail stick a piece of wood about 6x4in and half an inch thick, a coupling hook and a paper clip, not one of those fancy coloured ones but an old-fashioned one. There must be millions of these at the bottom of filing cabinets and desk drawers. You will need some simple hand tools which I imagine you already possess and a soldering iron.

If you already have a suitable hook then you can skip this section. I used ones found on an etch obtained at a Guild show. These etches are very thin to use singly so I usually solder two together to get a more robust shape. To do this, I only tin the coupling hook end of each matching etch then hold by the spine the two lined up in a hand vice. I then put the hand vice into a bench vice (or in my case into my workmate bench) and solder the hook end. Any tendency for the etches to part can be corrected by using a pair of pliers while the solder is melted. When the hook is inserted through the buffer beam and the coil spring put on, you can splay the etches apart to trap the spring without the job of locating a split pin.

Drill a vertical hole, 0.07in (1.8mm) in diameter, somewhere near the centre of a piece of wood, then push the 10BA screw fully down. Now drill a 0.034in (0.9mm) diameter hole at the side of the screw head. Keep the drill rubbing against the screw head and drill as deep as possible. Take small cuts at a time to avoid breaking the drill.

Next, take the paper clip and twist it apart and cut two U shapes from it. Lay one of the U shapes on the wood. Using flat pliers, fingers and round-nosed pliers, squeeze the U until the two prongs are the same distance apart as the diameter of the screw head, and parallel to each other as in the illustration below.

Now cut one stem off ⁵/16 in from the loop end, thread the loop into the hook and insert the long stem into the small hole in the wood. Push the loop right down until the short prong touches the wood. Depending on your chosen hook, it should not bind against the screw head. Ideally it should just swing clear with a minimum gap and to achieve this the ⁵/16 in dimension may need to be trimmed to nearly ¼ in. Once you are satisfied at this stage, the assembly can be soldered together. Carefully remove the assembly out of the wood and trim off the stem. Clean up with a file and you are halfway there.

The procedure for the link is similar to the above but the 10BA nut is supported on the pointed end of a cocktail stick. Drill a hole somewhere in the wood the same diameter as the cocktail stick, then screw the nut firmly onto the point. Insert the cocktail stick into the hole until the nut is touching the wood. Cut off the protruding stick from the rear but don't throw it away. Drill a 0.034in (0.9mm) diameter hole adjacent one of the flats on the nut, as described above. Take the other U shape of the paper clip. Squeeze it using pliers and fingers so that it is the width of the nut and parallel as in figure 2. Cut one prong to the ⁵/16 in dimension and insert the long prong into the small hole until the shorter prong touches the wood. The assembly can now be soldered together, taking care not to get solder into the thread. I found that this operation is best carried out using a pointed tip soldering iron. Remove the link from the wood, cut off the prong and clean up with a file.

The two parts can now be assembled and tested. Insert the coupling into the vehicle and, with it standing on straight track, try coupling it to another vehicle. Adjust the length until the buffers touch. It may be that the screw is too long to allow the link to slip over the hook properly, in which case the screw should be shortened slightly. Notice that the screw coupling now behaves like a single link which I find is much easier to handle than the usual type.

Some years ago I was given a shirt for Christmas and it was held to its backing with ball headed pins. I thought at the time these might be useful one day and I have used some of them to represent the bar that forms an important detail of the prototype. I cut them ⁵/16 in long, then soldered them on to 8BA washers. I then installed them loosely on the screw couplings and they look quite convincing.