![\"\"](\"https:\/\/ngtrains.com\/blog\/wp-content\/uploads\/2026\/05\/Dropper-Assembly.png\")
<\/a><\/p>\nTo that end I wanted dropper wires from the underside of the rail to locate with a mechanism under the board. Criteria were: –<\/p>\n
- \n
- Silver soldered so it won’t come undone<\/li>\n
- Consistent placement so that the rails become a known standard to mate with the mechanism below the board.<\/li>\n<\/ul>\n
That said I need a jig to me.<\/p>\n
That opened a bit of a can of worms that included a mild rebuild of my bandsaw whilst equipping it with a metal cutting blade to cut the aluminium for the jig.<\/p>\n
![\"\"](\"https:\/\/ngtrains.com\/blog\/wp-content\/uploads\/2026\/05\/Assembly-Jig-300x216.png\")
<\/a>On the jig the aluminium block is screwed to the back plate. In this picture there are two bits of rail glued to the far face leaving a channel for the rail to be soldered locating it parallel to the back plate but spaced off it.<\/p>\nAt the far right is an end stop, This has a Vee filed in it so not only does it set the distance it prevents the rail deflecting up or down.<\/p>\n
The dropper wire holder consists of two bits of brass tube silver soldered to a bit of brass angle. Two bits of tube were used because I had them to hand but they resulted in a happy accident. One bit moved a smidgen such that there is a very slight misalignment. The happy result is the dropper wire is held tightly and stays where its put. A couple of layers of card spaced the dropper holder up to the centre line of the rail.<\/p>\n
![\"\"](\"https:\/\/ngtrains.com\/blog\/wp-content\/uploads\/2026\/05\/Flat-on-the-Wire-300x215.png\")
<\/a>The droppers are 1mm diameter nickel silver wire. They are bent in a pair of pliers with the width of the blade acting as the depth gauge for the length of the bent bit.<\/p>\nOnce bent they are held in a pin vice and were touched on a powered sanding disk to create a small flat on the bottom to increase the surface contact of the soldered joint.<\/p>\n
The rail being used is Micro Engineering code 83 and its the weathered variety so the bottom face has to be cleaned of the weathering compound.
![\"\"](\"https:\/\/ngtrains.com\/blog\/wp-content\/uploads\/2026\/05\/Wire-and-Rail-Prepped-300x261.png\")
<\/a>Once clean both the rails and the droppers were left to soak in pickling acid for awhile –\u00a0 precise time being one cup of tea and two biscuits. This gives them a final clean prior to soldering.<\/p>\nWhat is silver soldering? Its a harder and higher temperature method of joining two metals. Whereas your soft soldering with an iron uses a temperatures in the 150 to 350’C range this is in the 600-900’c range. Its advantages for modelers is that it can be the first part of an assembly and subsequent soft soldering won’t make it come undone. In this case its that its a stronger bond and unlikely to fail in a location where fixing it would be a right pain in the nether regions.<\/p>\n