Catenaries

For starters: under a bridge - furthermore: poles

More text and pictures on this subject is published (in dutch) in Modelspoormagazine 49.

As I wanted catenaries on my layout, I first had to build it under a tunnel: The Boulroie station crossing. This wouldn't be reacheable after being placed. Its construction is described here:

I made a mould, using printed circuit board material, as this is heat-resistant but not heat-conducting. It can be cut and glued easily. For the suspension, I used brass profiles and 0,5mm steel wire. For starters, I cut these at 20mm length

Some millimeters from the edge, a 0.6mm hole is drilled in the brass H-profile. Once put in the mould, one steel wire is slipped through this hole. Another wire is slightly bent en put aside the first wire. They get soldered together, using tin-it 40/60 and some electronics core solder.

Once the support beam is soldered tot the main beam, the wires and profiles can be cut to the right length and angle. This is done using a diamond saw in my rotary tool. A footplate is made from thin brass. I imitated some bolts, using a scratchpin and a light hammer. This footplate is soldered to the rest of the catenary support while it is still in the mould.

Once this construction is done, the support can be safely lifted from its mould. After some first cleaning, an insulator, made from some spare Sommerfeldt parts, is shifted over the wires. As they are soldered together and are bendable, this is easily done.

The steel wires hold the insulator in place: no glue is needed. After cleaning, the catenary support is painted. The insulator gets matt black, the rest of the support a greyish color. The place is marked on the tunnel ceiling, a small hole drilled to fit the top insulation. Now the support is glued to the tunnel ceiling.

The catenary wires are made from brass and copper/tinned wire. Using a drawing program on my computer, a printed an exact scale length drawing of the wire construction. This is used as a base for further construction. The wires are cut to shape, a small hook is bent at the edges to fit the support wires.

Using masking tape, the catenary wires are held in place on the drawing. Using soldering fluid and core solder, they are fixed together. Wire edges are then cut off and sanded. After a thorough cleaning, the catenary is airbushed.

The top insulator needs a footplate, too. It is made from sheet brass. The center hole allows a very thin wire, holding the insulator in place.

Now the catenary wire can be installed. The connecting to the steel support wires is glued. On the edge of the top wire, the footplate-and insulator is placed. The right picture shows the result.

A H-shaped brass profile, 4 by 4 mm and an M3-bolt are the main ingredients.

These are soldoured together with a hot, solid-state soldering iron.

This joint, although tough, needs to be hidden. Some scrap styrene, milled to shape, will do as a way to make a master for moulding.

The brass profile is used to align the styrene bits while gluing them.

Some filing is needed to get master "in shape".

A master model ... that's for casting, right? So: put some masters in a small styrene box.

Silicon rubber is used to make the mould.

Our cast copies. We need little resin to cast these, so combining this casting with other castings is recommended.

The mast's base is now shoved from the top down towards the soldered joint, were it can be glued in place.

The result is a solid mast with a well concealed joint. Using an M3-bolt, it can be mounted firmly to the subroadbed.