I have been working on my first model for a while now and still have a long way to go before completion.

The goal is to have a real bridge console operate a model lift-span bridge. The console was taken out (replaced) in 1995. It is the original console (1964). The bridge is still operating.

The model is scratch-built from using photographs. Plans for the bridge are unavailable.

The project is for the local naval and maritime museum in Ballina, NSW, Australia.
I am a volunteer who had some background in electronics many decades ago. The museum got me to convert the console from an industrial to a low DC voltage apparatus.

The allocated display area is 1200 x 2400 mm (4 x 8 feet). This brings the whole bridge (across the Richmond River) to a 1/72 scale model.

Here is an image of the real bridge:


Here is the old console from that bridge:


My proposed layout for the project:


Please be patient with me in showing you the work in progress. The first several posts will be what has already been done. Then there will be delays in further posts as I am still working on the project. As mentioned, it is a scratch-build, and I am still trying to figure out what and how to do the next bit. Basically I already know what is to be done, but since I never done anything like this, it takes me awhile to actually venture into the unknown and experiment, so to speak, from one step to the next.

The museum is a non-profit organisation and has a limited budget, which limits the choices of resources. So my plans and reasons for doing things a certain way are often influenced by such restrictions. Naturally, I do many hours of searching for the cheapest items available. I often cannibalize and utilize other bits to access parts and materials for the project. Oddly enough, there is a certain amount of satisfaction gained from improvising and utilizing unexpected resources.

Hope you will find this project of interest.

Welcome to the forum and what a great project. I will be watching with interest.

Graeme

Welcome to the forum sounds a great project and certainly a little different, look forward to seeing your progress.

Al

The first thing I had to do was to find out how this console actually operated the lift-span bridge. I spoke with the current operator and found out that there is a long sequence of procedures. In a nutshell, both road and river traffic has to be controlled before raising the bridge. The model also has to be somewhat child-proof, so that nobody can lower the bridge onto the boat as it passes, and any other potential mishaps.

The planning, designing, and drawing of plans has taken up a fair bit of time. Scratch building is so different to having all the parts, drawings and instructions at hand. Because it will be a museum display, the model will be out of my hands as soon as it is completed. Others will need to know how to operate, troubleshoot and repair the model when need to. So I am also compiling an operation and service manual as well.

Here are some of my plan drawings. These were done on computer. other drawings, to save time, are photographs of my drawing drafts (free-hand). You will see those later on.

Overall idea of how I want the display to look like.


Both bridge and boat will be driven by electric motors with a 148:1 reduction gearbox, donated for the project. The drive system is via cables and pulleys.


A montage of some of my drawings for building the bridge and display table. All measurements in millimetres.


For those unfamiliar with a lift-span bridge, here is an animated GIF of how they work.

I decided to make a simple layout drawing of the control panel. I makes it easier for me to read and follow.



After opening the front panel to examine the console contents, drawings and iPhone photographs were made of the switch mechanisms and other bits. A lot of wires were cut when they removed the console. Disconnecting them from the terminal strips was the start of revamping the console.



The museum's workshop is too small to include this project with its on going work on other smaller projects. So this display is being put together in my lounge room. The timber arrived for making the display table and its attached Control Box (under the table).



The line you see across the table top is a 3 mm gap. This serves as a sliding guide for the traversing boat.



The Control Box has two doors for accessing the motors, pulley systems, and electronics.

Looks like a great start on this project I don't envy you with all the wiring.

Al

Thank you Tony, Al, and Jase.

At this stage, because the table-top and control box turned out okay, I was starting to feel more confident. To get a break from wood-work I worked on reverse engineering the control panel. The internal wiring harness made it impossible to lift up the control panel for closer inspection. I used my iPhone to take snapshots to see if I could use the wiring without modification. Damn! it was no use. I will have to rewire the whole panel to suit the DC controls. So the harness wiring got disassembled and stored for later use.

The curator wanted the console to still look antiquated, yet cleaned up. The museum president said it would be good if the museum visitors, especially the kids, could get to see what was involved under the control panel. Displaying photographs was discussed. Then I opened my big mouth and suggested to replace the front panel with a thick sheet of perspex. So now the console has become a wiring diorama as well. This means that the console interior will be under close examination. It needs to be cleaned up, painted, rewiring a coloured harness, and internal lighting.

Decided to use a dark bluish grey interior in the hope of highlighting the coloured wiring. Ironically, Dulux had the exact shade I was looking for and it's called Boatshed Gray.

The first added requirement to the console was a DC Power Supply Unit (PSU). This was a bit of a headache to design because I had to estimate its requirements as well as available parts to build it. I needed +24, +12, and =5 volt supplies that can handle about 2 Amps each. This is what I came up with.



Making the PSU.



Blown Fuse Indicators for each DC voltage line.



Testing the PSU. All worked fine from the start.



PSU mounted inside the console.

This is moving along well, looking forward to seeing it through to completion.

Al