Ceiling Mounted, 3D Printed Family of Housings for Home Automation Sensors (PIR, Infra-Red Remore Control, Light Intensity Sensor and Buzzer)

As an electronic engineer, over the years I have had great fun "making projects" of varying degrees of technique and effort. On looking at the final result of many of those projects, despite that great feeling of accomplishment that I gained from completing the technical challenge, I often was left with a feeling of "disappointment" that the housing arrangement that I had to select from those commercially and economically available did not meet my "pre-project" expectations of what the finished article might look like. The result although working brilliantly to its specification never made it to my home environment due to my wife's judgement that it "looked like something a geek has made in the garage" - a statement although rather harsh was not far from the truth.

The age of 3D printing has completely changed that situation and now an equal part of the project is ensuring that I have a housing arrangement that fits the technical and packaging requirements of the design itself whilst meeting the aesthetic demands of an unforgiving household.

Any home automation project these days presents many such "modules" that need to blend into the home and for sure, would not have been possible but for this technology and today I bring you one small part of that project that you can also adapt to your needs.

I have included STL files of all parts used and I have made my original CAD project on Tinkercad (www.tinkercad.com) public so that you access the master design should you wish to make your own version. (Search in the Tinkercad 3D gallery for "Omnidirectional Multi Sensor Housing" & "Single Multi Sensor Housing")

The project presented here is a range of ceiling mounted compact housings accommodating a mix of sensors used in any home automation type project, namely ....

1. DHT22 temperature and humidity sensor (Note NOT the DHT11 as this is smaller)
2. Light intensity sensor (GL5516 or similar)
3. Passive Infra-Red (PIR) movement detector (SR501 type)
4. Infra-Red receiver (IR) for IR remote control purposes
5. Small buzzer

This is the housing design only and no attempt is made to cover the wiring arrangement although for the sake of completeness, I have included the data sheets of the above devices in section 4.

All versions include a common mounting arrange based on a hollow tube (6) that goes through the ceiling (5), at the top of the tube above the ceiling is a two piece clamp assembly (3) that can slide up and down the tube. The clamp can be locked at any point just by tightening the 2 screws in the clamp.

Below the ceiling, a thin disc (4) can be fitted at a fixed point along the tube length. The clamp can be positioned to allow you to secure the total assembly in the ceiling by squeezing the latter between the clamp and disc.

The tube also serves as the wiring feed through the ceiling into the housing.

There are two versions of the sensor concept:

A. Omnidirectional cluster housing

This is a single ceiling mount assembly that has three separate sensor housings:

1. Housing (2) containing 1 x IR receiver, 1 x light intensity sensor & 1 x PIR detector
2. Housing (1), each containing 1 x PIR sensor only
3. Housing (1), each containing 1 x PIR sensor only

With this configuration, the assembly has a 360 degree movement detection zone

B. Single sensor housing

There are two versions of the single sensor housing:

1. Housing (1) containing a single SR501 PIR detector only
2. Housing (2) containing 1 x IR receiver, 1 x light intensity sensor & 1 x PIR detector.

The component parts of the three housing omnidirectional cluster can be broken down to;

• A. 1 x base plate and mounting tube cluster assembly - printed as one part.
• B. 3 x mounting frames for the PIR detector
• C. 1 x mounting clip for the DHT22 temperature and humidity sensor
• D. 2 x PCB guides (optional)
• D. 1 x large cover
• E. 2 x small covers
• F. 1 x Assembly top cover (optional)
• G. 1 x Assembly bottom cover (optional)
• H. 2 x above ceiling clamps
• I. 1 x below ceiling disc
• J. 2 x 3mm x 20mm self tapping screws (holds the ceiling clamps together)
• K. 2 x M3 nuts
• L. 6 x 2mm self tapping screws (for fixing the 3 housing covers to the back plate cluster)
• M - Assembly top cover
• N - Assembly bottom cover

All of the items apart from the nuts and screws are 3D printed and the STL files are listed for download in section 4

The PCB guides and PIR mounting frame are push fitted into the base plate as previously describe in Section 1

The component parts of the single housing can be broken down into the following:

• A. 1 x Base plate (large version or narrow version)
• B. 1 x Mounting frame for the PIR detector
• C. 1 x Mounting clip for the DHT22 temperature & humidity sensor
• D. 1 x Cover (large version or narrow version)
• E. 2 x PCB guides (optional)
• F. 1 x Mounting tube
• G. 2 x above ceiling clamps
• H. 1 x below ceiling disc
• I. 4 x 20mm M3 screws (mounting tube to the back plate and the above ceiling clamp pieces together)
• J. 1 x 10mm M* screw for fixing the DHT22 sensor to the base plate
• K. 3 x M3 nuts
• L. 2 x 2mm self tapping screws for fixing the cover to the back plate.

All of the items apart from the nuts and screws are 3D printed and are listed for download in Section 4.

The optional PCB guides simply push into a recess in the back plate to allow you to fit a 24.4 x 30 x 1.5 mm circuit board for any purpose that suits. In my project, I fitted a small 5V buzzer and a single op-amp IC circuit for local amplification of the photo resistor used for the light intensity sensor. It was a shoe horn fit but I got it in.

The PIR mounting frame is also a tight push fit in the recess provided on the back plate.

There is not a lot I can say re the 3D printing process itself as I can honestly say it was surprisingly straightforward.

For all of the items, apart from the items mentioned below, I used an UPBOX from Tiertime (www.up3D.com) with standard print settings of 0.2mm with both ABS and PLA and the items printed without issue.

See the picture for the settings that I actually used even though I did not find anything critical.

The software that I used was UP 2.18 supplied with the printer. This is not the latest version but still the one that I prefer to use.

With other printers, you may have to experiment with settings and the best orientation of the parts for the optimum printing

The covers and base plates will take the longest to print and in particular the covers and omnidirectional back plate will take some time post print to remove the support material that will also be printed.

See the diagram for the preferred printing orientation for each part based on my final experience.

(Most of the parts were printed separately to minimise waste if a problem occurred)

For the small parts below, I printed at 0.15mm simply to try to take care of the detail of the parts: Printing at 0.1mm resolution is even better but it prolongs the printing time and for me, I did not see a benefit.

1. PIR mounting frame
2. PCB guides
3. Below ceiling disc.

The following downloadable files gives you the complete set of STL files compatible directly with your 3D printer and/or third party printing contractor.

I have also included a data sheet of the devices used within this housing.