Inductive sensor holder for Diehl Corona MCI

Water meters frequently come with a half metal wheel that enables to use an inductive sensor as an impulse counter to read water usage data. The Diehl Corona MCI is such a device, it has one rotation per L. The inductive sensor must be carefully placed to get proper on and off signals (slightly off-center from the wheel to properly trigger on and off).

The Diehl sensor has a round shape with two nudges on the outer diameter that can be used to fix alignment of the sensor. My model is made for aninductive sensor of 18mm diameter with 10mm range (a smaller 12mm diameter and 4mm range did not detect the metal cog for me). It features an M18 thread (1mm pitch) into which the sensor can be directly screwed in and which can be used for tight fight alignment. A threaded insert (M3 x 5.7mm) for an M3 screw in the ring allows for better fixation of the holder to the water meter. I have also added a second model for a 30mm diameter inductive sensor which I used for some experimentation (without  holding screw and threading, use the screws that come with the sensor to fix). The larger sensor works, but I unified on the 18mm sensor for water and gas meter.

I have also created a matching case for an ESP8266 D1 mini pro and an ESPHome config for the water meter with a D1 Mini.

Print Instructions

I have used PETG, but any other material should work just as well. This model requires supports. You can use support enforcers to only support the holder top overhang and the thread cylinder. The incline at the back of the holder does not need supports, neither does the screw hole.

Assembly Instructions

After printing, insert the threaded insert from the outside and put it in place. Partially screw in the sensor (lower sensor end still above upper end of the holder ring). Place the sensor on the water meter, watch for the grooves on the meter fitting into the nudges on the holder. Add the holder screw, tighten it only slightly (just so that the holder doesn't move anymore). Screw the sensor all the way in. Verify that the sensor works (power it and test with a liter of water to see activation and deactivation).