Wow… well I’ve had the new Prusa i3 MK3S for a few weeks now and can’t believe I waited this long to upgrade. The print quality of the Prusa is great, and dimensional accuracy (especially with small features) goes way beyond what I’d expected. I have to say that I’ve gained an new kind of respect for the FDM process and printed components.
I’m impressed to the point that it appears viable (maybe even a no-brainer) to print our own enclosures rather than machine and modify the big bulky expensive shells covered in previous updates.
A downside of course is that prints are porous even at 100% infill. This is important to address because we want to keep water and moisture out with a high IP rating. Although the enclosure will be fully potted anyway, we still don’t want the case exterior taking on water.
Vacuum flooding a low viscosity silicone-based sealant may help offset that issue. I’m looking into it.
For now, this looks like a promising way to perhaps have our cake and eat it too. We can make the total package as small as possible right away. With great quality at a very low initial cost, and (importantly for me) the ability to quickly iterate to new designs without having to burn through stockpiles of inventory. I think I’m in love.
Size comparison with the other enclosure I’d planned to cut to length. Modifying the big one means we’d still end up with a lot of unnecessary width, height and internal volume to fill with potting compound ($).
Never hurts to live up to the name. (Smaller has to be better).
What are your thoughts/plans on mounting? Are you planning velcro, or perhaps some mounting ears?
I like the vacuum flooding silicon idea for IP. You might also consider exterior coating with an acrylic paint or perhaps plastidip would be functional as well.
Though, plastidip contains toluene, not sure what effect that may have on room temperature PLA (assuming you’re using PLA).
I’m thinking three reinforced mounting bosses with M6 stainless socket cap screws. One on each side and the third at the center top. With a rubber grommet and metal bushing in each. Should help against vibration and prevent the “strong armed” among us from breaking off mounts with one too many ugga duggas.
PETG seems to be the best material for the job. It’s tougher than PLA by a good amount and doesn’t rapidly degrade from being exposed to outside elements. Thermal expansion is lower. And it’s easier to work with and less expensive than nylon or polycarbonate.
…or so I hear. I haven’t tried it out yet myself. We’ll see how it does and go from there.
I can’t get over how far it’s come along in recent years, to the point of now being a serious manufacturing process for a growing number of applications. I love it. Right on brand for NanoEFI if you ask me.
Just my 2¢, but I wouldn’t use PET-G near fuel, as it softens it, I only know as I made some fuel gauge adaptor/spacers and was surprised by the results after 6 days or so.
I tend to use the carbon filled products in my automotive prototypes in the past that have gone in engine bays, and although my Hall effect sensor case was PET-G, I now use “BioPCs” that have a high VISCAT temperature rating up to 165ºC. There will be equivalents to Extruder Green TEC PRO in the USA I’m sure.
I’m anticipating that in most nEFI installations the ECU will be mounted out in open air. So my main concerns for now are UV exposure, and protecting from water ingress at different angles. If we start seeing a lot of engine bay installations early on, I may have to rethink this.
For now I think we’ll be fine with a note in the instructions that direct contact with fuel, oil, coolant, etc should be avoided. Eventually the cases will be injection molded, I’ve been leaning towards PBT+G for the material at that stage.
If you want UV performance go for an ASA derivative, as that’s what it is aimed at, but get a low warp variant. It’s as strong as ABS in your use case.
and thanks for your support! 
