The goal here was to develop a better way of attaching the sensor for the 1Byone Wireless Driveway Alert system to the side of the house.
I recently purchased the 1Byone Wireless Driveway Alert (picture left). The system itself works well but one area where it could do with some improvement is in the method the designers have chosen for mounting the sensors. The back of the sensors are flat except for a single screw-head slot (see Figure 1) which is meant to securely fix the sensor to a wall or post. This rudimentary way of mounting the sensor makes it almost impossible to position the sensor so that it focuses precisely on the area of one’s property that requires monitoring. In my case, if I were to use the provided means of sensor mounting to one of the outside walls of my house, the sensor would either pick up car and foot traffic on the road in the front of the house or it would pick up my neighbour’s comings and goings. In either case, this would have set off the sensor far too often with too many false positive alerts which would have rendered the system pretty much useless. Therefore, what was needed was some sort of bracket to allow for precise positioning of the sensor so that it would only be set off when movement was detected in the area of interest.
I live in a bungalow with a driveway that runs along the entire length of the side of the house and on up to the street, so the ideal place for the sensor in this case was on the fascia board just below the guttering on the side of the house. The sensor also had to face towards the street but angled downwards so that the area covered by the sensor did not include the public pavement nor the road in front. This would have been impossible to achieve with the mounting design (if you can call it that!) that comes as part of the sensor. So a bracket of some sort was needed to hold the sensor at a right angle to the fascia board and tilted downwards. After examing several different options both in the commercial space as well as considering making a bespoke bracket on a 3D printer myself, I finally settled on a commercially-available bracket from Toolstation that is normally used to hold a handrail to a wall.
NB: I did not end up using the actual one from Toolstation in the end, but instead one that I had lying around the workshop, which looks almost identical to commercially-available one, save for possibly a slight difference in the positions of the screw holes – see Securing the Sensor Holder to the Bracket section below. The bracket has a right angle to it (see Figure 2) which was ideal for having the sensor attach to the side of the house but still be facing forward towards the street. The bracket itself was made of brass (perfect for weather-resistance), and attaches to the fascia board via three screws within a circular plate. However, the screw holes on the other end that would be used to hold the sensor in place were too narrow for the M5 machine screws I planned to use, so these holes were made larger on a standard pillar drill using a 5.5mm cobalt drill bit. Finally, to match the colour of the fascia boards and sensor (ie. white), the bracket was brush-painted with white metal paint (in retrospect, spray-painting would have provided a better finish).
3D model of the Sensor Holder
With the bracket chosen and optimised, I now needed to find some way of attaching the sensor to the bracket. The sensor itself is not very amenable to modification and I did not want to start drilling holes in it to attach the bracket. This was primarily because the plastic that the sensor was made of did not look strong enough to support screw attachment directly, but also with each new hole I placed in the device, I would decrease the sensor’s overall resistance to the elements. Therefore, I decided on making a sensor holder that would not require weakening the structure of the sensor at all and that could be fashioned on a 3D printer.
To model around the irregular shape of the sensor accurately, the sensor was scanned on a regular flatbed scanner from both its back view and from its bottom view (a 3D scanner would have been preferable but since I dont’ own one…at least not yet!). Both scanned images were then imported into Blender (a free 3D modelling software from www.blender.org) and used to fashion a bespoke holder around the sensor (see picture right).
The sensor is supposed to be water-resistant but does not have an International Protection or IP rating like most electronic hardware that is designed to be exposed to the elements. Therefore, to further increase its water-resistance, the new sensor holder was designed as a continuous ‘hood’ around the upper, side and back aspects of the device. This was especially important since the sensor was going to be mounted with it tilting forward most likely exposing different parts of its structure to the elements than were likely expected in its original design.
The bottom of the sensor holder on the other hand was left open for two reasons. Firstly, there needed to be a way to insert the sensor into the holder (although this turned out to be unusable once I had printed it – see below), and secondly, by leaving it open, any rain water that did manage to find its way between the sensor holder and the sensor would have a easy escape route (incidently, the sensor itself looks to have been designed with a similar mindset as there are what appear to be four small drain holes at the bottom of the sensor (see picture right) presumeably to allow for water egress). Unfortunately, I did not appreciate how large the central bulge of the sensor was, so pushing the sensor up from the bottom opening proved to be impossible without cracking open the sensor holder. However, fortunately, it turned out that the sensor could be relatively easily inserted into the sensor holder from its front aspect when the sensor is pushed into the holder bottom first and at a 45° angle (video of insertion coming…).
Finally, as with the bracket, the sensor holder, which was printed in pink PLA plastic, was painted white with metal paint to blend in with the white fascia board on the side of the house.
Securing the Sensor Holder to the Bracket
Before the 1Byone sensor was placed inside the new sensor holder, the metal bracket was attached to the holder with two stainless steel M5 x 16mm countersunk machine screws. One point to note here is that the actual bracket I used was one that I found lying around in my workshop. It looks very similar to the one available from Toolstation (see link in the Materials table below), however, the positioning of the screw holes used to attach the sensor holder are not likely to be the identical to those of the Toolstation one, so these need to be adjusted on the 3D model before printing. To do this, scan the area of the bracket that the holder will be attached to using a regular 2D scanner and import the image into Blender. Adjust the image size to match its actual size in the model, before moving the holes on the sensor holder to the correct location (as per picture on the right).
Securing the 1Byone Sensor in the Sensor Holder
Before I realised that the sensor holder was inadvertently designed so that the sensor cannot possibly fall out from the bottom of it (see explanation above in the 3D model of the Sensor Holder section), I had already designed in a securing mechanism for the sensor within the holder. This consisted of a stainless steel M6 button screw and stainless steel nut that was secured to the back of the sensor holder (see picture right) with the tip of the machine screw protruding into the original screw-head slot on the back of the 1Byone sensor. A rubber tap washer was used to make the hole in the holder water-tight.
Securing the whole thing to the fascia board
A single 3.5 x 25mm stainless steel screw were first used to secure the complete unit (sensor + holder + bracket) to the fascia board under the guttering at an approximate downward angle so that the sensor could monitor the general area of interest. With a bit of trial and error and a lot of aimlessly walking around in the driveway to activate the sensor, I was able to adjust the angle of the bracket so that the sensor precisely covered the area of interest without encroaching into undesirable areas like the road and public footpath. Once the exact angle was established, the remaining two stainless steel screws were inserted to fix the whole thing permanently in place.
*Note the use of stainless steel screws and nuts for all fixings which were used to ensure protection from rusting especially since everything is exposed to the elements.
- .stl file of sensor holder (NB: check screw holes line up with your specific bracket before 3D printing)