To control the extractor fan I purchased a three-way switch that is labelled, “Man”, “Off” and “Auto”. The fan controller has a trigger connection and the idea is that this can be controlled from the light switch or in future a more sophisticated control such as a humidity sensor.
I wanted to use a standard metal box to match all of the others in the workshop. As you can see the switch is quite deep so that gave me an issue with the mounting. I purchased a box and a plain stainless steel blanking plate.
To give that extra bit of clearance, I designed a spacer using Fusion 360. To position the holes I used the parameters option which allows these values to be calculated.
It printed successfully first time although I could have left more clearance on the large hole as that required some filing to fit around the switch.
The hole needed in the front panel was smaller than my smallest hole saw but bigger than the step drills. So I marked it out and cut the hole using the Dremel. I then drilled the mounting holes which needed some fine tuning with a round file.
Retrospectively, I could have used the 3D printed part as a template and drilled the mounting holes first and added the body hole afterwards.
The switch was screwed on and the front panel was attached to the case.
The next step is to mount this on the wall and add some cable glands for the wiring. I also need to sort out a duct and grill on the wall.