The pieces did NOT exist in the 1970s. Fast microcontrollers, stepper motors, precision miniaturized manufacturing, reliable and cheap miniaturized DC electronics, and far far more technology was non-existent at any kind of affordable price point. Look at kitchen appliances or metal/wood shop machinery from this era, still heavily analog, mostly made from sheet steel, mostly non-computerized. The 80s would bring better microprocessors but even the simple Nintendo was an inflation adjusted $450. For comparison the first RepRaps used a full power PC as their host machine and their materials cost roughly $1000 in today USD and needed parts from a commercial stratasys machine.

Some of the greatest and most under appreciated technological achievements in the last 40 years have been in materials science and miniaturization.

I think it's probably correct that few people *really* cared until the Reprap project showed a real DIY 3D printer was possible.

Early machines were industrial machines with huge price tags, proper linear motion systems, complicated extrusion systems and so on. There is a bit of a mental leap to go from seeing $100k+ machine and dreaming to design something that can be built for $200-500.

The problems were: no "reference designs", no tried and true go-to mechanical parts (like cheap chinese linear motion rails), extruders (they were DIYd!) or heated beds (early models were just PCBs) and so on - imo it just took someone to get this rolling and that may have well taken 30 years.

I think Reprap was first publicly shown around 2005. From then on it was taken on by more and more makers and refined. It culminated in the early 2010s hype with Makerbots and its contemporaries but they still cost > $1500 and were far from set-and-forget appliances, like 50% reliable and slow - we had one at work and I got fascinated but it printed at 5-20mm/s so parts would just take forever and often fail due to bed adhesion, clogs, ...

The last 10-15 years then have seen the popularization of 3d printers through the Prusa i3 and its clones (Ender and other cartesians < $300) and steady refinement of reliability through better materials. Then the last ~5years or so significantly bumped up the speeds through better linear motion components, motion systems and input shaping + firmware and ecosystems like Klipper.

Bambu imo got in at just the right time and refined everything that had culminated up to this point into a solid appliance. Imo their genius was more in the industrial design, making it reliable and affordable manufacturing than anything else.

It was invented but protected by patents, so it wasn't until those patents expired that companies and hobbyists started to experiment. Early 3D printers hadn't figured out things like layer adhesion yet so parts tended to be too weak to be very useful. It wasn't clear that this was an area for improvement rather than a fundamental downside of the technology.

What needs would home 3D printing fill in the 70s?

A complete set of woodworking or metalworking tools was a lot cheaper than a home computer. And there were entire magazines dedicated to proliferating free or easily obtained schematics/designs. Labor was also cheaper, and people had more time for hobbies.

I would also argue the point that it would have been relatively cheap. We are used to the ubiquity of cheap DC motors and precision parts being a click away. But if you were to rummage through a vintage Radio Shack to cobble together a home printer, I think you would struggle to construct anything precise enough with consumer available parts.

> a melting plastic

Don't sleep on the chemistry of filament. It has to be extremely precise and consistent. We benefit from the massive economies of scale today, but this was small batch stuff 20-30 years ago. And if we are talking about the 1970s the plastics were really primitive by today's standards.

3D printers were first invented in the 80s. There's a combination of several factors why they took off in the 2010s:

1. Cheap stepper motors and electronics from China

2. Expiration of Stratasys patents in 2009

3. Widespread availability of CAD software and desktop computers powerful enough to run it

4. Reprap project made it easy for companies (and individuals!) to develop their own printers

A mixture of patent protection, China’s (lack of) precision manufacturing at scale at that time, and software immaturity. LM8UU around 15 years ago when I started my 3D printing journey was upwards of $15 PER PIECE. You need at least 8 for a Mendel or i3 style printer during the reprap boom. Just the bearings alone would have cost you, $100 or so. Then factor in chrome rods, stepper motor, stepper motor drivers (Pololu just released their A4988 boards), you’re looking at almost $1K just for the parts. The software like slicers and even gcode interpreters weren’t even made yet. Merlin wasn’t even a big thing until about 10 years ago. We take for granted how much work the community has put into 3D printers to get us where we are today.

You could buy a 3-D printer from Stratasys in 1990, but it cost $178,000! The printing unit was $130,000 and the Silicon Graphics workstation with slicing software to run it was $48,000 more. So the technology was there, but two orders of magnitude too expensive for the consumer market. Patents account for part of the cost, but the computer to control it was also way too expensive, as well as the custom (vs commoditized) mechanical components.

Link: https://books.google.com/books?id=0bqdMvDMv74C&pg=PA32&dq=st...

Have you ever seen 1970s CNC gear? I came across a 1970s CNC lathe in a surplus store once. The thing was the size of a small car. The electronics box was the size of two racks. Inside were cards that handled one bit of one register. Input was from a paper tape. No CPU; all special purpose electronics.

Directly controlling industrial machines from a microprocessor was very rare before the 1980s.

3DBenchy.stl, the little boat that everyone prints as a benchmark during 3d printer reviews, is 10MB.

A 10MB hard drive cost $3,000-4,000 in 1980.

That's $12k-15k today.

Just opening the .stl file and having it render (USABLY) on screen in high-resolution was probably not economical until the late 1990s-early 2000s.

I am used to computing tasks being human-perception instant. It takes tens of seconds to run repairs on 3d models, which means it would have taken tens of hours to do that same thing, if there was even enough RAM, in the 90s.

> All the pieces existed to make a working 3D printer existed even in 1970! and relatively cheaply. So why has it taken so long for 3D home printing to actually become a thing?

Easy. The printing process itself is not that hard.

It's the model _design_ that is tricky. We needed home computers to become powerful enough to run 3D CAD software, and enough people to get proficient with it.

RepRap started in 2005. Realistically, we could have had it maybe a few years earlier. But not _much_ earlier.

Some observations that I didn't see in the other comments:

- Home 3D printing is often more of a hobby than a traditional prototyping or engineering discipline. People view it as a skill to have, and a fun use of free time. Note how the cheapest and most finicky ones are popular; they can be made to work well through careful operation, troubleshooting, procedures, customization etc. They are not set-and-forget, and I think the userbase likes that.

- Home 3D printer parts (the motors, frames, electronics etc) are almost exclusively sourced from China. We live in an AliBaba world; that wasn't always the case.

When I started my Industrial Design degree in 2007 the workshop there already had several large, commercial 3D printers for student use.

Mind you they were nothing like the tabletop consumer ones we have today. They were about the same of a large American refrigerator.

Since it was not really any special or amazing for us to have several of them, I have to imagine that industrial 3D printing capabilities were well established by the point.

Edit: as I recall they were mostly used to make parts which could be given a nice surface finish and then from which silicone molds could be made.

I don't know that I'd argue that "consumer" 3D printing, as in a printer at home that just churns out a part when you want it, is even really hear yet, certainly not in the way that a dishwasher or lawnmower is. You need to do your own slicing, thinking through supports and brims and layer height, and the printers themselves need no small amount of troubleshooting that is much more than "turn it on and off again". So, I'd argue it's still a hobbyist realm than a consumer one.

Patents do explain some of this delay....

Fused Deposition Modeling or FDM (1989, expired in 2009), Liquid-Based Stereolithography or SLA (1986, expired in 2006), Selective Laser Sintering or SLS (1992, expired in 2012), metal processes like Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS) (1996, expired 2016).

One thing to think about is you'd need quite a beefy machine to even properly render the gcode in the 70s and 80s. In this age of printers computers often didn't even have fonts, they were ROM cartridges your printer would take. And even into the 90s there were accelerator cards for printing documents and talking to the printer in alternative ways than parallel ports.

So really, for an average hobbyist the idea of a 3D printer controllable from a home PC wouldn't really be possible until like the mid 90s. So you really need to start your look at why it wasn't a thing at some point in history I'd start the digging there, not the 1970s.

It was the polymers that needed to be invented. In the 1990s we used to order quick-turn prototype 3D prints for parts to check fit before committing to tooling for hard materials, but we only had 3 days to work with it before it fell apart into a puddle of goo.

I don;t think anybody was really doing FDM/FFF until the 90s and it didn't really take off until the 2000s. It was quite expensive, required a high level of expertise in both mech E and CS, and existing subtractive methods (like CNC and lathe) were very effective.

The magic ingredients were inexpensive microcontrollers, massively paralleled mosfet transistors (also a product of large scale integrated circuits, since they are actually millions of tiny mosfets working together), and the expiration of several key patents that made it possible to have a commercial explosion around the reprap scene.

The patents expiring was a big deal, since the main patent was on the fused deposition process itself.

The other factor was that normal desktop computers had become powerful enough to run sophisticated 3d modeling programs and make machine motion computations from 3d design files.

There weren't good CAD tools to send the designs to the machine until recently. Early CAD tools mostly produced drawings and it was a separate step to manufacture from there.

The way inkjet and laser printers work is also quite different from the way a 3d printer works. The similarity is mostly in the gantry, so there was nontrivial innovation required here.

To some extent 3d printing is probably also a reaction to decreased access to domestic manufacturing. It doesn't make a lot of sense to produce most parts in plastic if you can get a cast or milled part quickly and cheaply.

Part of it is technological advancement. It wasnt until the last 15 years or so that embedded processors became cheap and powerful enough to run a 3D printer at consumer prices.

There's also the problem of 3D modeling and slicing. Again up until quite recently, 3D CAD was out of reach for most consumers. Either due to hardware capabilities or cost of the software. Slicing is its own entire branch of 3D processing and it took time to develop all the techniques we use today that make it fast and reliable. Slicing software could only exist after the printers were common.

As well, I expect the availability and materials science of the plastics we use needed some further development.

As I recall, 3D printers rose to prominence at about the same time and speed as we started getting genuinely powerful personal computers. You really needed a fast CPU, and printing became more accessible as the early I5/I7 generations became cheaply available.

While you absolutely could build an FDM printer with 80s technology, I don't think it could ever be practical or affordable. Even if someone invented all the computational techniques for slicing, the compute available back then was not even close. It would literally take an actual supercomputer to slice your model. It'd take many, many hours on any consumer computer. This would hold true until the early 2000s. At a random guess, I'd say the tipping point would have been around the Pentium 4.

So, same as most technologies we take for granted these days. Enabled almost exclusively by the speed and capacity of computer available to consumers.

Working 3D printers existed long time, but only SLS and very expensive.

Only in 2000s appear things important for cheap 3D printer:

1. Cheap power semiconductors.

2. Cheap 32-bit microcontrollers.

3. Powerful computers, to run slicer, and free slicer.

4. For photo-sensitive resin appear large 2nd market of powerful semiconductor lasers and light-modulators (from DLP projectors).

To be more exact, FIRST powerful transistors appear in 1970s, but become cheap in 1990s; microcontrollers similar, but before 2000s cheap 32-bit does not existed; microcomputers become enough powerful for 3D printing in late 1990s and appeared home CNC motion; lasers are still grow, they now have something like Moore law.

So to conclude, yes, sum of technologies need for cheap 3D printer appeared around Y2K, but then few years spend by fans to construct practice equipment and make first shipment to customer (Prusa made his design around 2009).

1. Patents 2. Cheap CAD 3. Arduino (IMHO...before this it wasn't easy to interface to USB/PC for anyone who wasn't EE) 4. Surge of DIY online (Forums, mailing lists, instructables, pinterest) 5. Reprap leading the way with recycled parts as well as cheap imported motors and controllers. 6. Lack of interest- Machinists could usually do the same thing but better using subtractive. Additive was seen as "useless" for real world items even after reprap.

There are probably a couple other things I am missing...and what order you place my list probably doesn't matter. It took everything at once happening.

In my experience, it really took off when PLA filament became commonplace. ABS and UV-cured epoxy emitted noxious fumes which required separate ventilation systems and weren't really suitable to be used at home.

Early home 3D-printers also required more of the user. It took a lot of tweaking to make them produce decent prints.

Just having a computer that could handle working with relatively complex 3D models, not even visually but just via the terminal, would have been a tall order in the 80s. Even getting the data from the computer to the printer would be tough. Floppies wouldn't store enough data for even modestly complex 3D model files. Parallel port? Would be painfully slow. But even if you get around those issues, the algorithms for transforming the 3D model into 2D layers that could be printed with the proper support structures and with minimal material used are extremely complicated and involved a lot of intermediate data during the calculations. Most machines then wouldn't have had even close the amount of RAM needed to do that in any reasonable amount of time.

My father was an industrial design professor and I remember him showing me a 3D printed element in the early 00’s. He explained at the time that it’s the future but just way way too expensive and unstable for actual use cases. Chicken or egg sort of thing - I agree that it took the internet to exist

1. Patents. 2. CAD software was HUGELY expensive for a long time. 3. Parts were expensive. economy of scale on things like linear bearings made this crazy. I recently took apart my first gen printrbot (it cost me ~$600 and was one of the cheapest ones at the time) and it was all brand name VXB bearings. because that's basically all that existed.

Are many people going to buy a home 3D printer? It's not a profitable business.

It took that long because nobody was working on it, because it wasn't obvious that a low-cost 3-D printer was feasible.

The 3-D printers you're seeing today are basically the series of RepRap designs, named after famous scientists who studied self-reproduction: Darwin, Mendel, and Huxley. The RepRap project, which started in 02005, is the reason this happened. For the first several years, it was about half a dozen people: Rhys Jones, Patrick Haufe, Ed Sells, Pejman Iravani, Vik Olliver, Chris Palmer (aka NopHead) and Adrian Bowyer. The last three of these did most of the early work. Once they got it basically working, after many years of work, a lot of other people got involved.

There were a series of developments that had to happen together to get a working low-cost printer. They had to use PLA, because the plastics conventionally used (mostly ABS) had such a high thermal coefficient of expansion that they needed a heated build chamber. They had to design their own electronics, because Arduino didn't exist. They had to figure out how to build a hotend that wouldn't break itself after a few hours. They had to write a slicer. They had to write a G-code interpreter. They weren't industrial engineers, so they didn't know about Kapton. They wasted a lot of time trying to make it work without even a heated bed, to keep costs down. They improvised leadscrews out of threaded rod and garden hose. They made rotational couplings from aquarium tubing. Lots and lots of inventions were needed to get the cost down from US$60k to US$0.3k, and lots and lots of time was wasted on figuring out how to get the resulting janky machines to be reliable enough to be usable at all.

Starting in the mid-90s, Don Lancaster was excited about 3-D printers, which he called "Santa Claus machines" https://www.tinaja.com/santa01.shtml, when he could see that they were possible. He wrote lots of technical articles about building what he called "flutterwumpers": "low cost machines that spit or chomp". https://www.tinaja.com/flut01.shtml. For example, in https://www.tinaja.com/glib/muse140.pdf in 01999, he describes Gordon Robineau's low-cost PCB drill driven by MS-DOS software over a serial port, with a schematic. (The fishing-line cable drive sounds imprecise, since this was years before Spectra braided fishing line.) But nobody listened. I don't know if he ever built so much as a sign cutting machine himself.

Journalists like to talk about the patents, maybe because they're legible to nontechnical people in a way that difficulties with your retraction settings aren't, but when I was obsessively reading the RepRap blogs in the period 02005–02010, I can't recall that they ever mentioned the patents. They were just constantly hacking on their software, fixing their machines, having then break again after a few more hours of printing, and trying new stuff all the time. I don't think the patents even existed in their countries, and they were researchers, anyway, and generally patents don't prevent research. Maybe there's a vast dark-matter bulk of for-profit hackers who would have gotten involved and started up profitable consumer 3-D printing companies before 02005 if it hadn't been for the patents, but who never got interested because of the patents.

But what I saw was that businesspeople started commercializing RepRaps once the open-source RepRap hackers got them to work somewhat reliably. Before that, they mostly weren't thinking about it. After that, most of them spent a lot of years shipping very slightly tweaked RepRap designs. Josef Prusa got involved in the RepRap project and redesigned Ed Sells's Mendel, and everybody copied him, and he famously started selling it himself, very successfully. https://reprap.org/wiki/The_incomplete_RepRap_Prusa_Mendel_b... And more recently Bambu Labs has apparently gotten the machines to be much easier to use.

Memory?

We take 1GB for granted. In the old time is 4kB was expensive achievement.

And you need a lot of memory to store g code for useful 3d model.

Short answer is, there is no need. Personal computer were sold to make nice printed paper. Here there is no specific application.

The answer to this is the same reason why flying cars aren't ubiquitous. Inventory and discovery is often the easy part.

Is it actually better than homes built by other methods?

The most expensive part of home is general the land it's built on.

Micro-stepping controller chips.

Before that, the precision available without gearing and feedback wasn't sufficient. There were systems but they were order of magnitude more complicated and several orders more expensive.

Stratasys patents.

Computers in 1970 were so slow we hacked in saying lightness, a scientific measure of color, was the average of the two highest color channels.

Equivalent statement: "A flying car is just a car with wings, what's so difficult about that???"

I knew someone who recycled paper printers into a home brew 3D printer and then a 2D shopbot style CNC.

Patents