Here’s a little tip about tech blogs, and journalism in general: absolutely everything you read is one hundred percent true, except in the cases where you – the reader – know anything about the story being discussed. Those stores on Wired and CNet where a device using an ARM Cortex-M3 is described as having, “the same CPU as a modern-day smart phone?” Totally legit, unless you know that running Android on such a chip is a virtual impossibility.

Such is the case with ‘key 3D printing patents set to expire in 2014’ – a phrase bandied about tech blogs with the fervency of news the seventh seal has been broken. If you believe everything you read on the Internet, we’re looking at a world of 3D printed lollipops, unicorns, and rainbows in just a few short months. Following the logic of journalistic veracity above, this obviously isn’t the case. What does the expiration of these patents actually mean, then?

Let’s Back Up A Bit Here

The current crop of 3D printers use fused deposition modelling, FDM, or the ‘squirting melted plastic’ method. This technique was patented in 1989 by [Scott Crump], co-founder of Stratasys, one of the largest manufacturers of 3D printers. This patent expired in 2009, and there’s no coincidence 3D printing really started to pick up around that time with the development of the Reprap Mendel and the founding of what was previously the Open Hardware community’s golden child, Makerbot.

If past results are any indication of future performance, the expiration of these key 3D printing patents will result in yet another boom in the field of one-off manufacturing, rapid prototyping, and some really cool projects coming out of hackerspaces in the next year or two.

And Here Are The Patents

The ‘key patents‘ (just search for [Carl R. Deckard] as the inventor if you want more) referenced by hundreds of articles spread out all over the Internet involve selective laser sintering. What is SLS, you ask? It’s actually pretty simple: take some powder, shoot it with a laser, let the powder melt, and put a dusting of new powder over the mess you just created. You can use a wide range of plastics with SLS compared to the FDM Repraps and Makerbots we have today; you can even print in metal and make yourself a rocket engine. If NASA is doing it, it has to be awesome, right?

So What Makes SLS So Great?

Even though the current lineup of ‘squirting plastic’ printers is fairly capable and can do a lot in the right hands, there’s some stuff an FDM machine such as a RepRap or Makerbot can’t do. Overhangs are possible, but for very intricate shapes – a one foot tall scale model of the Eiffel Tower, perhaps – you’re looking at a world of hurt. The only way an FDM machine could print something like that is with two filaments, using one material as a support and later dissolving it away.

The same goes with printing parts inside parts like the popular ‘ball in a cage’ carving project. No squirting plastic 3D printer can do this without supports, but an SLS machine makes it very, very easy.

SLS also allows for many, many different materials. While most FDM machines will not see a filament besides ABS and PLA, laser sintering machines can print in just about any powder that melts. Everything from nylon to polycarbonate to metals are possible with laser sintering.

Finally. lasers allow for much higher accuracy than the most common 3D printers. While very accurate FDM machines can print with an accuracy equal to that of a human hair, this isn’t the case for the majority of RepRappers out there. SLS simply doesn’t have the problems of oozing and misaligned layers so common in home-built printers.

Why You Won’t Have an SLS Printer in Your Garage

Oversimplifying everything a great deal, these printers are basically made of two parts: a laser cutter on top, and a plunger and roller system to build up parts layer by layer below. Simple enough, right? Let’s just do some back-of-the envelope calculations on how much it would cost to build our own SLS printer.

First things first. We’re going to need something that moves a laser beam around on an XY plane. Here’s a fantastic Open Source laser cutter that does just that. The BOM lists the component costs (minus a laser tube) at about $850. Throw in an eBay CO2 laser tube from China, and you’re looking at a fully functioning laser cutter for just about $1100. That’s awesome, even though it’s right about in line with the cheap, smaller-capacity Chinese-made laser cutters you can get via the usual channels for about the same price.

That’s half of our build right there. Now all we need is some sort of roller to dispense the powder and a plunger mechanism to build a part layer by layer. This is where things get a little more difficult. You’re probably going to need some sort of sheet metal build tank to hold all that powder, and the plunger will need to work at some fairly tight tolerances. The roller is simple, but you’ll also need some way to (somewhat) evenly spread the powder in front of the roller. In the end, you’ll probably looking at around $2000-$3000 for a low-end, home built SLS printer.

Here’s the problem, though: we’re around the price point of a Makerbot or Ultimaker – both proven machines – and an SLS machine is not going to be that much better. You’re still basically only working with plastics, and while you don’t have to deal with support structures on our DIY laser 3D printer, you’re not doing anything that can’t already be done with a stereolithography printer like the resin-based Form 1 printer for the same price.

As for printing in metals, that’s a pipe dream for any machine cheaper than a car. Sintering metal with a laser requires a vacuum chamber, diffusion pumps, and some very hard core equipment to do it right. Not to mention you won’t be able to melt any appreciable amount of metal with a 40 Watt laser. While there has been some progress with a similar project called MetallicaRap, the MetallicaRap team estimates their final kit will cost about €10,000, out of the range of just about every hobbyist or hackerspace.

By the way, the MetallicaRap project is really awesome and you should think about a small donation to the project.

Basically, if you don’t know how to build an electron microscope or fusion reactor in your basement, you don’t have the skill set to design a machine that can print a usable metal part.

If not homebrew, then what?

The reason everyone is so excited by the expiration of ‘key patents’ is the fact that other large companies besides 3D systems – Stratasys and Zcorp, for example – will be able to manufacture their own SLS printers. That’s great and all, but even 3D systems, the maker of these SLS printers only use them for their professional range. The bulk of professional printers produced by these companies use a method similar to SLS – using an inkjet to spray binder onto powder – but this isn’t covered by the SLS patents.

If anything, the expiration of these key patents will mean a reduction in cost for the very, very high end printers. The stuff NASA uses. Of course a few large companies will be using this tech for custom, one-off parts, but don’t expect to see any laser sintered parts show up in your car’s engine any time soon. Remember, 3D printing and rapid manufacturing is only ideal when you need to make a handful of parts. Anything more, and you’re better off with traditional manufacturing methods.

In Closing…

Will the expiration of key 3D printing patents in 2014 change anything in the arena of 3D printing? Well, large, already established 3D printer manufacturers will be putting out cheaper printers that can print in metal. You’ll be able to buy a 3D printed rocket engine for a few hundred dollars instead of a few thousand. Once Shapeways gets their hands on one of these machines, you’ll probably see a few extremely tiny internal combustion engines built by hobbyists. There will probably be a flood of combination 3D printer / laser cutter machines on Kickstarter. Other than that? It’s going to be cool, but patent expirations aren’t going to change the world overnight.