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Lego's 0.002mm specification and its implications for manufacturing (2025)

thewave.engineer

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Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#211

Post by perfmode »

rkangel wrote: post #77

The tolerance for interference fit ("clutch power" in Lego terminology) is important, but that's fairly simple. It's the cumulative tolerance when you assemble large structures that's important. Knockoff bricks can be fine for the first few you assemble, and then as the structure gets larger things don't quite fit together. Also interesting is that in very large models, there is decoupling between sections. Lego has…

This is the most interesting point in the thread to me. Tolerance stack-up is the reason tight per-part tolerances matter at all. A single brick being precise is table stakes for injection molding. The hard problem is what happens when you compose hundreds of them. The decoupling strategy you're describing is really similar to how you handle error accumulation in any large composed system. You can't make individual components perfect enough to avoid drift at scale, so you introduce boundaries where the accumulated error gets absorbed rather than propagated. In Lego's case that means designing joints between sections that are forgiving enough to accommodate the stack-up from each chunk independently.

It's also why knockoff bricks can feel fine for small builds and then fall apart (sometimes literally) on larger ones. If your per-part tolerance is 3x worse, it doesn't matter much for a 20-piece build, but for a 2000-piece build your cumulative error budget is blown long before you're done. The failure mode isn't that any individual brick is bad, it's that the composition doesn't hold.

I'd be curious whether Lego publishes or talks about those chunk size design rules anywhere. That seems like the actually interesting engineering story, more so than the per-part tolerance numbers that get repeated in every article about them.

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#212

Post by maxglute »

cruffle_duffle wrote: post #203
maxglute wrote: post #187

Earlier quoted context omitted.

My point is lego has ceiling on imagination. Different in analogue world where most of building was physical. I grew up with buckets of mismatched lego and lots of technic sets, it was more interactive relative to other toys at the time, but now snapping bricks vs running server for minecraft city seems like baby mode.

And that is the thing about raising a kid these days. Those damn machines have replaced so much… because yeah Minecraft is like a souped up version of Lego where in creative mode you have every part you need. And you don’t have to dig for it or anything. And it has survival mode and a whole huge thing on top of that. It’s so difficult to know the boundaries. People from older generations giving advice about screen ti…

> completely uncharted water

Good thing with analogue toys like legos is you know your kid is playing with legos that is wiring X brain cells for Y skills, even if Y skills are deprecated in digital world. It's hard to say with current gen, there's screen time to try to shape behavior, there are occasional kids who are tech literate maestros which every generation has, but plenty of kids who rely on LLMs, can only finger type because they grew up with touch screens. We're in tech timeline where passive users, i.e. most kids are impressed by millennials who can write cursive and touch type, other kids build stuff that previously required teams of 100s of engineers.

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#213

Post by autoexec »

mytailorisrich wrote: post #209
autoexec wrote: post #197

Earlier quoted context omitted.

For most people anything that has only kept up with inflation over the last 50 years is more expense today than it was 50 years ago because wages have stagnated while prices have soared.

No, that's not the case. For instance, the median household income in the United States in 1976 was $12,686. That's $72,857.55 today based on inflation (Google/Census Bureau Data + online inflation calculator). However, Google's AI overview says " As of early 2026, the median household income in the United States is estimated to be approximately $84,000. " So the the median household income in the US today is about $…

> in real terms average hourly earnings peaked more than 45 years ago: The $4.03-an-hour rate recorded in January 1973 had the same purchasing power that $23.68 would today. (https://www.pewresearch.org/short-reads/2018/08/07/for-most-...)

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#214

Post by basilikum »

scatbot wrote: post #12

Lego is one of those companies that is simultaneously amazing and kind of sucks. On one hand the core product is incredible. The tolerances on the bricks are micrometer-level precision and the fact that pieces from the 70s snap perfectly into ones made today is mind blowing. On the other hand, a lot what the company does today just sucks. Set prices are outrageous. Printed bricks get replaced with stickers and many s…

Just buy from one of the many way cheaper way better competitors.

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#215

Post by galaxyLogic »

mytailorisrich wrote: post #209
autoexec wrote: post #197

Earlier quoted context omitted.

For most people anything that has only kept up with inflation over the last 50 years is more expense today than it was 50 years ago because wages have stagnated while prices have soared.

No, that's not the case. For instance, the median household income in the United States in 1976 was $12,686. That's $72,857.55 today based on inflation (Google/Census Bureau Data + online inflation calculator). However, Google's AI overview says " As of early 2026, the median household income in the United States is estimated to be approximately $84,000. " So the the median household income in the US today is about $…

Ok, but, what about median household size? Shouldn't we calculate the "richness" based not on how much each household makes but how much each member of a household gets from it? My guess is that households are smaller these days, but don't know.

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#216

Post by mytailorisrich »

galaxyLogic wrote: post #215
mytailorisrich wrote: post #209

Earlier quoted context omitted.

No, that's not the case. For instance, the median household income in the United States in 1976 was $12,686. That's $72,857.55 today based on inflation (Google/Census Bureau Data + online inflation calculator). However, Google's AI overview says " As of early 2026, the median household income in the United States is estimated to be approximately $84,000. " So the the median household income in the US today is about $…

Ok, but, what about median household size? Shouldn't we calculate the "richness" based not on how much each household makes but how much each member of a household gets from it? My guess is that households are smaller these days, but don't know.

Well if today's households are smaller that makes them even richer (more money split over fewer people).

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#217

Post by kroolik »

cruffle_duffle wrote: post #192
Xerox9213 wrote: post #140

Earlier quoted context omitted.

Buying buckets of used bricks is pretty cheap, too. I bought an adult's old lifetime collection for $30 CAD. My 2 year old son and I are still sorting them.

Sorting Lego is such a pain in the ass. I have like a huge stash from when I was a kid. Back then we just had it all in a few tubs and dug to find a part. But somehow now I feel I must sort them… but the “right way” is ill defined and kind of sucks the joy out of playing (especially disassembling) And there is no “right way” that I’ve even found. Sort by color and now the little pieces fall to the bottom and are hard…

Build with what pieces you can find, rather than plan the perfect structure ahead. Improvising keeps the creativity going! Wheres fun if sorting legos sucks all the Joy from it

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#218

Post by vikingerik »

scatbot wrote: post #12

Lego is one of those companies that is simultaneously amazing and kind of sucks. On one hand the core product is incredible. The tolerances on the bricks are micrometer-level precision and the fact that pieces from the 70s snap perfectly into ones made today is mind blowing. On the other hand, a lot what the company does today just sucks. Set prices are outrageous. Printed bricks get replaced with stickers and many s…

If you're complaining about the prices, remember how capitalism works. The price is set by buyers, not sellers. That's the invisible hand, the seller will set the price to what buyers show they will pay. If you're unhappy about $500 for a Millennium Falcon or whatever, your beef is not with the company for accepting that when people choose to pay it, it's with those other buyers for paying that much.

As the other replies are saying, it's mostly brand power. If your complaint is that $500 for a Falcon is monopolistic because there's no competition because nobody else can legally sell Falcons, the monopoly is really with Star Wars not Lego, they're just delegating it to Lego. You're always free to find your cheapest source of bricks perhaps from other manufacturers and build your own equivalent.

As for stickers and apps and the other stuff... yeah that's the enshittification that also always accompanies capitalism. It's lamentable but it only changes if enough customers vote no with their wallets.

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#219

Post by eszed »

johnisgood wrote: post #205
Aurornis wrote: post #113

Earlier quoted context omitted.

The existence of specialty sets doesn’t subtract from creating building. My kids get some of the specialty sets, build them, then hours later they’re either taken apart or heavily modified. The specialty sets can provide some interesting unique pieces too. My kids have a photographic memory of each of those special pieces and which set they came from. They’ll remember them and search until they find that exact piece.…

Off-topic, but: > My kids have a photographic memory How do you know it is photographic memory? More than one of your kids have it? Do you know why or what may have contributed to its development?

> Of each of these special pieces

I didn't see him making any generalized claim. I recall the things I'm really into better than I do things I'm not, which is all I think he was saying about his kids. (My four year old remembers facts about volcanos - including the name of the scientist who made the claim - waaay better than he does where he left his shoes, so it tracks for me!)

Re: Lego's 0.002mm specification and its implications for manufacturing (2025)

#220

Post by SV_BubbleTime »

Something that took me years of working with custom plastic injection part experience to notice still kind of shocks me…

Legos don’t have draft.

That means nothing to 99% of you, but someone else here must understand what the implications of that are for releasing from molds at a mass scale.

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