It’s not waterproof. I got the sheet metal parts from Schaeffer AG [1].

Thanks!

3d printing is here to stay, but load bearing parts are problematic. I had to change some of them to metal.

[1] https://www.schaeffer-ag.de/

How thick and what material is the sheet metal? Is it something that fit and be machinable on a cheap 3018 CNC mill?

(Sorry if that's answered in your linked post, I skimmed it perhaps a little too quickly...)

I used 4mm thick, black anodized aluminum plates. I'm not a machinist and do not know the specifics of your CNC machine, but you will most probably have no problems machining these plates.

Thanks!

(I'd be able to make those, I would probably need to do it in a few passes though.)

Did you try to print with nylons and carbons? I am currently in the progress of designing a fast robust RC car. I am very pleased with the durability of it. With standard pla/abs and pet I kept getting broken suspension parts. With nylon I haven't had a single failure during testing (+100mph). You have to design your stuff with plastic in mind, but you can make strong parts for sure. No doubt metal is better for most applications, but still it is doable.

I used PETG. I’m happy that I tried it, but it is hard to make 3d parts work, when they are subject to loads.

Speaking of (hobby) 3d printing and loads, why don't I see printed parts combined with extruded aluminium profiles (rectangular tubes or T-shaped), threaded steel rods and some nuts+washers more often? Those reinforcement elements are cheap as dirt and should be almost as easy to work with as legos when you can guide all the difficult connections with bespoke printed adapters. What am I missing? (I have zero experience with 3d printing, I barely get beyond kneading a pack of Sugru...)

I work in robotics and this is very common for prototyping and also common for grad student projects. Here in Japan, Misumi will machine things like that to length and add whatever features you need, or even configure an entire assembly (eg a 6 sided box) and get all the parts delivered. I don’t recall the name of similar sites in other countries but they exist.

Other easy things to get a good result is use nuts or inserts instead of threaded holes when you can, and try to keep printed plastic parts in compression, not tension.

I think not enough people use sheet metal. Doing as you described plus sheet metal to put some material on the outside of the cross section not only looks professional, it adds a lot of stiffness. And for aluminum sheet 0.5mm or 1.0mm thick you can literally cut it with a knife and straight edge, and use a couple of pieces of wood or even books to make surprisingly nice bends. For thicker or more complex parts, it’s pretty easy/cheap to make or buy a decent brake, and also pretty cheap to get parts made from sites like I described above.

I think a lot of 3D printer hobbyists turned to 3D printing once it got good enough because we don't have space or easy access to even cut things or have a stash of parts. You're right, I can get a M6 x 1200mm stainless steel rod for AUD$5. But then to cut it accurately would need a few more tools. So you kinda try and limit things to what you have. And you can do quite a few useful things with just 3D printed piece and the odd screw here and there.

Yeah, I think the thing with the more exotic filaments is that it's a more specialized used case for when you still need to retain the lightness of plastic. With something like this, the weight doesn't really matter and you want the big increase in strength or durability that you get with metal. Otherwise I find that correct design in your parts provides enough strength in most 3D printed parts to just use PLA or PETG. Nylon is quite a bit stronger but not worth the effort to try and print.

I also think the carbon filaments are BS. I've seen several tests like this one: https://www.matterhackers.com/news/filament-strength-testing

The carbon fibre nylon is worse than the plain nylon in terms of strength. Which makes sense to me. If you grind up carbon and put that into your filament why would that make it stronger? Maybe for compression forces?