Magnet Mount for Ei Electronics Ei650i Smoke Detector

About 10 years ago, I installed several Pyrexx PX-1 smoke detectors in my house, as I had found very positive reviews about them at the time. As an additional benefit, I appreciated their overall design and the fact that they allow for mounting using a magnet, making replacement much easier than the usual mounting option using screws.

Now that they are aging and need replacement, the situation seems to have changed since multiple reviews point out that they tend to show a late reaction to smoke compared to other products. Based on the review at https://www.faz.net/kaufkompass/test/der-beste-rauchmelder/ I went with the Ei Electronics model, though I chose the non-connected but much cheaper Ei650i model.

The main drawback of that model is that it only comes with screw mounting, and I didn't want to drill holes into my wooden ceiling.

As a result, I designed an alternative mounting cover that allows insertion of the metal plate from my old Pyrexx models. With this alternative cover, I can mount the Ei Electronics smoke detector to the existing magnet mounts already installed.

If you find yourself in a similar situation, you might be interested in this model.

Originally, I wanted to print this with ASA, but since I didn't have white ASA at hand, I went with Prusament PETG. I printed the model on my Voron printer. A time-lapse video can be found here: 

While the precise material and printer for sure do not matter much for this application, I am mentioning this since the tolerances of the model matter a lot. And since different materials shrink with different factors when cooling, using other materials might need minor adaptions of the tolerances in the model.

Even for my material choice, there is still a minor flaw in the model: The latch that is supposed to snap in when installing the cover is not yet precise enough to actually snap in. Since the cover is a tight fit for me, even without the latch, I decided to leave that imperfection for fixing in future iterations.

The model already has built-in support structures where needed, such that there is no need to activate supports in your slicer.

I printed the model with 0.2mm layer height, though other settings likely should work as well.

I also increased walls to 4, used 5 bottom and top layers, and increased infill to 40% for additional strength, though this likely is not strictly needed.

I am interested in hearing feedback about your experiences with the tolerances of the model and if it also works with other models from the Ei650 series of smoke detectors. Remixes for other metal plates or magnets are also welcome.

To install the cover, you first need to disassemble (and destroy) an old Pyrexx PX-1 smoke detector to remove the metal plate for reuse. This metal plate you press into the new cover. It should be a tight press-fit. Do not forget to remove the built-in support structures with pliers, since you will be unable to install the cover if you forget to do so. Finally, you install the cover on the smoke detector in the same way the original cover would have been installed. Note that this will activate the smoke detector. The complete assembly should attach to the magnet at your ceiling easily.