My own enclosure

[ttielemans]

I wanted to make my own enclusore. I paid attention on printability, ventilation and flexibility. The enclosure orientation is horizontal or vertical. The side walls can be swapped out for different designs. The PCB is attached with small self tapping screws. The top with 4x M2.5x12 mm bolts (8mm would be ideal but I had 12mm in stock).

The case was printed with eSun PLA+ on my Prusa MK3 with 0,2mm layer height and no supports.

The STEP/STP file is available on my google drive.
https://drive.google.com/file/d/1R2aJRWKAr5R3vcG7h97ao5NLkBjwaHvD/view?usp=sharing

The 3MF files (I prefer 3MF instead of STL)
https://drive.google.com/file/d/1Qokz7NuxpzFrb7aSjuQmoETKw9WD1VEs/view?usp=sharing

[Achim_AirGradient]

@ttielemans This is awesome!
It’s great that the community has more choices with enclosures. Are you ok if I link to here from our main DIY enclosure website?

[ttielemans]

Hello Achim, sure.
Thank you that you like it.
You can share it as you like

[Achim_AirGradient]

Great, I added the link here: The AirGradient DIY Sensor Enclosure

[cmartens]

I was wondering what the distance is between the upper side of the pcb and the bottom side of the litter. Basically I would like to know the maximum height which can be used on top of the pcb so that the pcb will still fit in the case. Thanks in advance.

[ttielemans]

The distance is 22.4mm (even decimal because of 0.2 layer height for 3d printing).

To adjust the height is easy to do. If you would like more height, tell me and I make a special case for you (at no cost) .

[brianFromNyc]

I test printed this case. I’m really liking it so far.

I do need to check the calibration on my printer because the fitment is really tight. The side pieces required a bit of clean up in order to slot in, and the board doesn’t sit down in the holder spot. This is 100% a problem with my print settings, not the design. I’m just mentioning it because anyone else printing on a printer that isn’t quite calibrated may face the same issues.

The only feedback I have so far:

• It would be nice if the closure screws were on the back for a nice clean look.
• The PMS5003 shrouds aren’t necessary if the air sensor is pushed flush against the case side before adhering to the board. Yes, this means the sensor will sit offset from the template marked on the board, and actually protrudes over the PCB board edge, you wouldn’t notice it because it is inside the case.
• The fan could be secured against the case edge without adhesive if a short divider is added to the top piece.
• The case bottom and case sides could probably be printed together (as one piece) - and without supports - because the printer should be able to bridge the small gaps at the tops.

[ttielemans]

Hello Brian,

Thank you for the feedback.

• Screws on the back is a good suggestion and should be very doable.
• I personally prefer to use screws to attach the PMS to the board. In case adhesive tape is used, the shrouds can be ommitted.
• Good idea for a variant without screws.
• The very fine ventilation holes did not print very nicely in vertical orientation and that was the reason to make all sides in such a way to print the horizontally.

[ttielemans]

I have made some small updates.
Moving the screws to the bottom is a bit more complex than expected and is still on the todo list.
It is ofcourse a matter of preference. Having the screws on top is more convinient for assembly.

In order to compensate somewhat the “temperature leaking” I have added two new elements with a 20mm and 30mm extension for the SH3x.

I share now the folder instead of the files so that updating is more convinient.

https://drive.google.com/drive/folders/18hyBFjyJzBdfCH8klpFMiMLU_LZll0Xh?usp=sharing

BTW what works nicely is the concept of the replacable sides. I can now swap out the sides without the need to reprint the whole case.

[dominic]

nice case and no risk of breaking the probes clips during instalation! i do like the idea of separating the temperature sensor from the rest, but having it stick out of the case doesn’t look clean. so my idea would be to have it as a chamber inside the case itself with big ventilation slots to the outside of the case only. but no openings towards the inside besides one small hole where the cables can be fiddled through before soldering. afterwards that hole can be sealed with some hot glue or so. thoughts?

[ttielemans]

@dominic I just had a quick look at your suggestion. The distance between the PM and temperatuur sensor is just 1.4 milimeter. Even with a wall thickness of 1.0mm, the tolerances are small. The areas where the PCB crosses the walls can also be a bit tricky to get closed enough to have any effect.

What would interest me is where the heat is created. Is there somebody in this group with a thermal camera that can make some pictures of the airgradient? Maybe there are other areas of the PCB that are less influenced by other components.

[Achim_AirGradient]

We did extensive testing. The heat is generated by the PMS module and then conducted mostly through the PCB to the temperature sensor.

I also experiences with a small wall but it did not help much. This is why we have in our professional sensor and the new DIY kit that I am currently designing a big air gap between PMS and temperature sensor.

I do not think you can get an accurate temperature reading inside the small and current compact DIY sensor.

[Achim_AirGradient]

I just looked up our old testing for our professional sensor and have to slightly correct above.

Most heat is generated by the S8 and D1. However, since the PMS sensor is metal it conducts the heat much better and acts as a kind of transfer towards the temperature sensor.
Here is a thermal image we did at that time:

and here is a comparison of having the PMS powered off on the PCB vs off the PCB:

As I mentioned earlier we did extensive testing and one of the reasons why our professional sensor is bigger is that we just need the physical space for the separation of the components to achieve an accurate temperature reading.

[lbhm]

@ttielemans

I share now the folder instead of the files so that updating is more convinient.

https://drive.google.com/drive/folders/18hyBFjyJzBdfCH8klpFMiMLU_LZll0Xh?usp=sharing

I have a small question regarding your files: What is the purpose of the part “Plug for probe”? I opened it in an online 3mf viewer and could not really make sense of it.

[ttielemans]

I made it to close the hole to minimize potential heat transfer. It is force fitted in place (no glue required).

[byrnespj]

@ttielemans I like this case! Would it be possible to get a version of the top without the lcd cutout? Thanks!

[Indymx]

I mounted the PM sensor with VSB tape rather than screws, I wonder if that will help with the heat transfer issue… Perhaps even block some of the heat from the CO sensor…

[ttielemans]

@byrnespj Hi, I have added “Top side without LCD hole” in the google drive.

[ttielemans]

@Indymx Hi, I have build various cases. The best solution for the most accurate temperature reading is using the temperature and humidity sensor of the PMS5003T . Second best option is a case with the temperature sensor in the side with the extension.
Accroding to my experience, the impact of the case is rather low.
Do you have any measured deviations with the taped solution (measurement with the sensor and a reference thermometer)?

[Indymx]

I have not done that yet. I haven’t put anything in a case yet either. I have an assortment of other temp sensors laying around, I’ll wire one up to another esp32 and sit in near the sht31 but with a few inches of air gap and let that sit for a while grabbing data and see what the difference over time is.