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Fire Monitors Part 2

The fire monitor columns are constructed from two lengths of brass tube with various bits added, either for appearance, or for function. The short tube is 8mm o/d and has a brass collar added. This tube will eventually be glued into a hole in the cabin roof. I had to make these tubes a little longer than shown on the plan to ensure that the rotating monitor would not foul the lifebelts on the engine room roof. The second, longer tube is 7mm o/d and forms the rotating column. It will slide into the shorter 8mm tube. It carries the water from below deck up to the monitor at the top of the tube. A brass bush is soldered into the top of the tube and the monitor body is soldered into that bush. Part way down this tube, a brass collar is soldered to act as a bearing point against the top edge of the larger tube when everything is assembled. The bottom of the 7mm rotating tube was plugged with brass and then drilled and tapped with a female M5 thread. The servo coupling is a brass boss with a disc of 0.5mm brass sheet soldered on. This was then turned to be circular before 4 brass pins were added to engage with the servo arm. The top of the boss is threaded with an M5 male thread to screw into the rotating column. A short length of 3mm copper tube is attached to the side of the boos to provide the water connection point. The centre of the M5 screw is drilled out 3mm to allow the water to pass into the rotating column. Plasticard was used to add some details to the columns and then the monitor was rigged up on a mock up of the cabin roof and connected to a servo to test out the rotation. An electronic was built to give 180 degrees of rotation for the monitor. I would have liked a little more, but the servo doesn't seem capable of accepting more than 0.5 - 2.5mS pulse width. Finally everything was stripped down, de-greased and painted using rattle cans. First with grey etch primer and then with 'Toolbox red' as suggested by Robbob. I have just realised, while writing this that I should not have painted the lower sections of the rotating tubes as these need to slide into the shorter tubes. Ah well, it will be easy enough to scrape that bit of paint off! (I'm sorry that the photos are not ordered in the correct sequence for the description. It doesn't seem to matter how I name the photos, or upload them, they just take on a random order of their own. Anyone know a solution to this?)

5 years ago by Graham93