Please feel free to suggest amendments and additions to either the preamble or the list of tools and resources above!
Great idea for a thread.
For considerations I think it is worth noting RF requirements. Often this precludes the use of metal enclosures when using internal antennas, where because of their environment, they would be best suited. It may be also worth mentioning potting as a form of enclosure.
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EMI is an important issue to deal with and good reason for a metal/faraday enclosure. Either external EMI like in a machine environment or in the case of radio gear where secondary frequencies/harmonics/etc need to be blocked from getting out.
Also, let us not forget aesthetics. Even for a CNC machine in my shop, I want my electronics case to look good and professional.
A build technique you left off is sheet metal bending. F360 has a really nice sheet metal module that makes it super easy to make cases and, for homebrewers, a brake is pretty easy to build.
[opinion alert] On the subject of PCB as case material. While I know people do it, it makes for a terrible enclosure. Sharp edges and poor fit are pretty common. It think it has a terribly unprofessional look to it. Several Open Builds products are like that. I have seen it used for a faceplate where the edges are recessed and it looks good.
I have never had the need for a Faraday cage. Solving the EMI at the source is cheaper. Granted, you might have a special circumstance, I don’t know. My designs has included VF drives with high dV/dt and we have never had the need for shielding
If you use Metal enclosure, and have mains in, then you need to comply to bond wire testing and touch current etc
About enclosures, if you have openings for cooling, rule of thumb is that slots needs to be wider than 1mm for reasonable air flow
For “why bother with enclosures”, I’d add:
- EMC / EMI / “grounding”
- Heat rejection, thermal compliance / performance
Some interesting reading on isolation and enclosure grounding is at 4000 - Electrical and Electronics Systems, Avionics/Control Systems, Optics | Standards, specifically HDBK-4001. The “lessons learned” section is also interesting reading. There’s a fair amount of overlap with non-aerospace RF and automotive.
A common enclosure design scheme in aerospace and other harsh industrial environments is the “bathtub” with a flat sheet lid. The bathtub has openings on the “bottom” (bathtub orientation) where bulkhead connectors are mated. A flat lid is attached over the bathtub and that becomes the “bottom plate” that is thermally / electrically coupled to the chassis. PCBAs tend to look like this example from soeffects.com:
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FreeCAD is great for enclosure, bracket, and heat frame designs IMO. The learning curve is steep and the first few times I tried it, I wasn’t convinced it was any good at all (but it’s really good). It also has a decent sheet metal plugin which I’ve used to design various U-shaped enclosures. Nearly every action you take in FreeCAD shows up in the python console as something you can then take and script. It’s a good way to start collecting scripts to programmatically/parametrically duplicate an enclosure design with different dimensions.
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We are currently working on a project that has 28 CCTV cameras. The customer was unhappy with the $15 grey plastic junction boxes for the ethernet termination at the camera and insisted we come up with a better looking solution. So we quoted stainless steel junction boxes, that due to the environment they were in, had to be the fancy stainless steel (316), not the ordinary (304) stainless. Each junction box now cost $300 (excluding glands and fittings). The customer agreed that they were a better looking solution and signed off on it. It must be nice to have money 
If the client is spending a good chunk of money on NRE and the first run, finding a way to make the end result look good even if you/we/me have to absorb some of those costs means the client has something that looks the part, reflects their investment in the techy bit and acts as a calling card for our next project.
We live in the Apple design world now. People have “stuff” made that they don’t really understand and many of the people that they show it to may not understand, but hopefully they understand what it does and as Apicius said “the first taste is always with the eyes”.
It would be useful if we could share our low-cost looking-good techniques.
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You missed my total nightmare “component”, one that has been plaguing at least one project with very small batch sizes for months:
“The Window”
I have projects with small LCD status displays. Having them mounted nicely but behind at least one piece of transparent material to stop people poking the display with a finger, biro, screwdriver etc etc has been an ongoing nightmare.
Cutting the case and getting a window to fit nicely - meh. Please tell me someone knows how to do this.
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@nmcc, do you have an example of what you’re trying to build?
For me, even something seemingly simple as lining up a LCD comes out better when everything is dimensioned and parts are made/cut by machine. Getting comfortable with 3D and 2D CAD has been critical for me to do enclosure work.
If you want to do the enclosure yourself, a 3D printed cover plate (with holes for displays, lights, and connectors) with a clamshell housing is probably the easiest way to go.
Then, add a professionally produced coverlay – Maverick Labels (Custom Industrial Labels And Equipment Labels (Free Shipping)) offers samples. There are many other vendors that do this work – search for “nameplate” and “overlay” to find them.
BTW, https://www.takachi-enclosure.com/ makes nice enclosure products and offers customization services (CNC, coverlay, engraving).
No display, but here’s an example of a project I did with an inexpensive snap-together box from
https://www.budind.com (PC-11476) and a paper + laminate coverlay that I did with a Silhouette machine. In this particular case, I CNC’d the openings in the front cover piece, as it wasn’t a straight plate:
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I make liberal use of Hammond enclosures, as they have a small minimum qty (normally 25) and cost for custom versions (custom = CNC’d) is pretty similar to off-the-shelf. If you have a mill it’s even better because you can do the customizations yourself at prototype phase:
Or use a 3D printer for the end panels. I’ve even 3D printed a full “belly plate”, but here is for example the end plate detail (the ‘belly plate’ on that is also 3D printed):
Using this has given me basically 100% success on the test CNC item Hammond sends back.
If you combine the CNCd cases with laminated vinyl labels (I use a local print shop, but previous threads have good links like ‘Maverick Labels’ that might be more suitable in USA) you basically end up with something that looks as good as “real” test equipment in most cases IMO.
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I’ve used a laminated paper label with a cutout (in the paper) for the window. This was just a one-off, but I assume you could get a self-adhesive label printed with a clear section for the window. I guess it depends how “poke resistant” it needs to be!
Sorry guys, I think that’s only visible on the consultants’ side of the forum. You could ask the the OP to change its category but bearing in mind people may have answered in context of the limited audience it may not be the kindest thing to do. We can extract links into a post on this thread (I’ll try later once I’m on my PC).
Good catch! I updated my post to point out Maverick Labels and the search terms to use to look for other similar vendors.
Just now circled back to this topic. I’ve been playing around with laser etching powder coated metal plates. Pretty amazing stuff. Took me some time to really dial in the process and I am still working on multicolor but I am very happy with the results. The photo is of a 4 mm aluminum panel cut on a CNC machine, powder coated with the semi-gloss black and then etched with a 40W CO2 laser. Note - 4mm because I happened to have it. Much thinner would work. A bit more detail is in my blog on the topic.
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that looks good. i’m looking forward to doing some laser cut metal panels and anodising at home for panels as well. but powder coating seems a lot less of a hassle and still nice finish, great work.
I have thought about anodizing over the years but the acid and mess of it always dissuaded me. Powder coating is so easy and almost no clean up (compressed air to blow the excess dust out the door). Plus, it is a lot tougher than an anodized finish. I can barely make a mark in it with a screw driver.
I have to say I’m more impressed by your powder coating than I am the laser - that seemed really out of reach until I read your blog.
yeah that’s what i’m thinking too, anodising is such a mess, i just like the colours ! we can do some of that with the laser but also silly hard to control
i just hadn’t really considered doing powdercoating at home either
I bought my set up from Eastwood. Got the “Dual Voltage Gun” (140, though on sale right now, sigh), some extra powder containers and several powders. They have a single voltage gun for about $100 which I probably could have gotten by with. Harbor Fright has an even cheaper one ($80) that would probably work (not really that much to it). I had a thrift shop toaster oven that I use for reflow. Bought an air filter and pressure reducer from HF.
It turned out to be really easy. If you do reflow at home, this is way easier. It’s not quite as exciting as watching your ICs and components snap into place but it’s pretty close. The trickiest part is getting it into the oven with out it touching anything. Anything it sits on will leave a mark. I used sheet metal screws in the mounting holes as standoffs.
There is a related technique called “hot flocking”. Basically, if you heat up a part to 400F, pull it out of the oven and sprinkle on the powder, it will stick. You can do glass that way. I’m going to experiment with using something like a powdered sugar shaker to see if we can skip the gun altogether. Dirt cheap if it works.
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