alt Hacker News3D printing is to mechanical engineering what vibe coding is to computer science.
With the rise of accessible 3D printers that can print engineering materials, there are a lot of people who try to create functional parts without any engineering background. Loading conditions, material properties, failure modes, and fatigue cycling are all important but invisible engineering steps that must be taken for a part to function safely.
As a consumer with a 3D printer, none of this is apparent when you look at a static, non-moving part. Even when you do start to learn more technical details like glass transition temperature, non-isotropic strength, and material creep, it's still not enough to cover everything you need to consider.
Much of this is also taught experimentally, not analytically - everyone will tell you "increasing walls increases strength more than increasing infill", but very few can actually point to the area moment of inertia equation that explains why.
3D printing has been an incredible boon for increasing accessibility for making parts in small businesses, but it has also allowed for big mistakes to be made by small players. My interpretation is the airshow vendor is probably one of these "small businesses".
Replies
Ehh.
Everything you need to consider is really not that much when it comes to most typical consumer 3d printing projects. Mostly because they are usually about stuff like "fixing a broken tashcan". The engineers who made that bullshit plastic part that broke after a year probably knew all about area moment of inertia, but that doesn't mean I need to to print a replacement part that lasts longer - or not, in which case I'll just iterate on my process.
I really don't get the dismissiveness, and frankly, I've never experienced that from engineers in my life. They just seem delighted when someone, kid or adult, tinkes with additive manufacturing.
I call bullshit. 3d-printing is just a manufacturing method. Basic woodworking is much cheaper and more accessible than 3d-printing, do you call it vibe-coding?
You don't need to be able to mathematically jerk the equation off to understand why increasing material at the perimeter adds more strength than the center (within reason and in typical cases) or why you probably shouldn't use something that melts around 200deg in an engine bay.