RepRap: An open-source 3D printer for the masses

IDG News Service — Tue, 04 Mar 2008 15:57:44 -0800

Imagine the last time something in your house broke -- a cup or plate, a bracket, a door handle, a component in an electrical appliance or mechanical device, a hinge, a switch. The list can go on and on. But instead of tossing the entire device out, or heading to the local hardware or electrical store to find an often costly replacement, imagine if you could recreate that object or component in your home on a 3D printer. Now imagine if the 3D printer you use to make that part could recreate itself as well.

This idea of self-replication has been around for some time, but until recently such technology has been far from the reach of the average person, costing tens of thousands of dollars to setup.

But researchers at the University of Bath in the UK gained worldwide attention in 2005 with the RepRap project -- an open source self-copying, rapid-prototyping machine that can manufacture mechanical parts and even reproduce itself at a fraction of the cost.

RepRap is short for Replicating Rapid-prototyper -- a self-replicating machine often described as a 3D printer that can manufacture components by building them up in layers of plastic. This technique is known as Fused Deposition Modelling Rapid Prototyping.

Software development for RepRap was done using Linux, and all of the project's software and hardware components fall under the GNU General Public License, meaning the design specifications are free for all to use and improve upon, with only several hundred dollars required for materials.

The design for the first version of RepRap, known as Darwin 1.0, has not yet been finalized. But it is close enough that kits are available for sale and early adopters have already began building their own, safe in the knowledge that when the time comes to upgrade, the RepRap can make its own parts.

Currently, Darwin 1.0 can manufacture about 65 percent of itself, excluding electrical circuitry, motors, nuts and bolts. The next version of RepRap - Mendel 2.0, will boast an electrical conductor allowing the machine to make its own and other circuitry, bringing it one step closer to complete self-replication.

Video demonstrations of the RepRap in action can be viewed here, along with items the RepRap can produce.

Within the next five years the RepRap team envisage that it will be possible to manufacture 90 percent of a mobile phone or MP3 player on the RepRap.

Computerworld recently spoke to Dr Adrian Bowyer, founder and head of the RepRap project at the University of Bath. Dr Bowyer talks about RepRap's capabilities, its history, why its hardware and software components are open source, and where self-replicating technology and the RepRap are heading in the near future.

Where did the concept for the RepRap come from, what was its inspiration?

Really it was inspired by symbiosis. The classic example, of course, is the symbiosis between flowers and insects, which has been going strong for 140 million years. As every school pupil knows, the flowers give nectar to the insects, which then transport the flowers' pollen because the flowers can't move. Both species benefit.

I thought: suppose one made a machine that copied itself and lived symbiotically with people? Specifically, the machine (analogous to the flowers) would make other goods (analogous to the nectar) in addition to itself, and people (analogous to the insects) would help it to reproduce by putting its parts that it had made together. That should be a stable symbiosis that would be proof against, for example, mere legal or financial pressures.

Why is the primary goal of the RepRap project to replicate itself, and not just to build anything?

Because self-replication is the most powerful and stable force we know. It gives exponential growth (which is always checked by finite resources). And it is subject to Darwin's law of evolution, which drives it towards evolutionarily stable strategies (like the symbiosis I mentioned).

Once you have a machine that can copy itself, you have a path to being able to make anything under the laws of physics.

Who is the RepRap aimed at and what need is it addressing in today's society?

Initially it is aimed at geeks and hackers, like any new technology; they are the ones with the skills to make early machines work. But of course it will evolve - that inescapable Darwin's law again. And one very strong evolutionary direction will be towards simplicity of assembly and use. The simpler it is for people, the greater the population of symbionts the machine has to collaborate with.

What is the benefit of having the entire project under the GNU GPL license? What benefits are there in RepRap being open source?

If you have a machine that copies itself, the only thing you can do with it is to give it away. Try to sell it, and you only sell one... Try to protect it legally and you spend the rest of your life in court trying to stop people doing with the machine the one thing it was designed to do...

The GPL forces people who improve RepRap to make those improvements available to everyone, thereby maximizing the rate of evolutionary progress. I personally gain nothing from giving it away, of course. But I don't need anything, and I enjoy running the project, so that's fine.

What kind of software does the RepRap run on?

RepRap software is platform independent and runs on Linux, Windows or a Mac. But all our development is done under Linux, and will almost certainly continue to be so.

Since the RepRap makes its own parts which can then be used to build another RepRap which can be used to build another, and so on, will there be a degradation of mechanical accuracy with successive generations?

Good point, but not a problem. Or rather, this was a problem solved centuries ago at the start of the industrial revolution. Lathes, for example, are made with screw adjusters so that you can get everything aligned and parallel, even if the parts aren't quite true. All you need to be able to do is to make something on the lathe and then measure it accurately to prompt the adjustments. That is simple. RepRap works in exactly the same way.

How much of itself can the RepRap manufacture?

Not counting nuts and bolts (which outnumber everything else in RepRap by an order of magnitude), about 65 percent.

What parts of itself cant the RepRap manufacture?

Mainly motors and electronic chips. We have designed the RepRap machine so that every part that it can't make for itself is available all over the world from multiple suppliers (usually the corner hardware shop...) and is cheap.

Are there plans to modify the current design to replace non-reproducible parts such as bolts with parts that can be manufactured on the machine itself, bringing the overall RepRap design closer to 100 percent self-reproduction?

Yes - that is definitely one of the evolutionary paths to greater reproductive success. For the immediate future I will be concentrating on widening the list of materials that RepRap can build with (starting with electrical conductors). That widening will implicitly raise the proportion of parts that it can make for itself, of course.

What is the current limiting factor with regard to making the RepRap work faster?

House room. If you have a self-copying machine, and you copy it, your rate of working goes up: 2, 4, 8, 16, 32 times etc. In short, it can go as fast as you like as long as you have room for the machines.

You mention three areas key to reducing the cost of building a RepRap: the software used to send the 3D model files to the RepRap, the physical electronics for the RepRap, and the RepRap printer design. What are the major obstacles you have come up against in reducing costs in these areas?

To be honest, there haven't been any major obstacles. It has taken (and is taking) time, of course - there are only about 10 of us, and most of us have day jobs. But -- fingers crossed -- we haven't yet hit any insurmountable problems.

Can the RepRap recycle what it manufactures?

Yes, recycling has been built in from the start. Though I personally think that RepRap landfill is much more environmentally friendly; I'll get to that in a few sentences. The main plastic we are using is polylactic acid. Anyone can make this by fermenting starch, so if you have a few tens of square meters of land to grow a starch crop you not only have a self-reproducing machine, you have a self-reproducing source of feedstock independent of the petrochemical industry. And polylactic acid is completely biodegradable.

So if you make junk in your RepRap machine, or if something made in it breaks, you just throw it on your compost heap and six-months later it's ready to be dug back into your next starch crop. Thus we have a complete, carbon neutral (except for the power used by the RepRap machine -- about 40 watts; and you could easily run it off a photo-voltaic), local, recycling route involving no transport at all and no industrial production.

But I want to move to using a non-biodegradable resin. This too is sourced from biomass, but is stable in the ground. That means that the more reprapped goods that get made from it and thrown in landfill, the more carbon is taken out of the atmosphere and locked away for good. And, in 200 years when we have taken so much carbon out of the air to make stuff that anthropogenic global cooling is starting to be a problem, the landfill sites become our strip coal mines to save us.

What is the RepRap shot glass tradition?

That was started by a Kiwi - Vik Olliver. He designed the glass, which is easy for the machine to make and which allows us to test things like how much overhang we can build unsupported. Now anyone who makes a machine starts with the glass, and toasts the new machine in that glass that it has made for itself.

How will RepRap 2.0 Mendel differ from the Darwin 1.0 design?

The two main differences will be:

Firstly, it will also build with an electrical conductor, allowing the machine to make its own (and other) circuitry. This may even include simple electric motors.

Secondly, it will have a range of material write heads that it can pick up and put down automatically. RepRap 1.0 "Darwin" has two fixed heads, allowing it to work with two materials simultaneously. Mendel will work with half a dozen or so at once.

There will be other technical differences, like we may change the microcontroller that the machine uses, and we may switch from using stepper motors (precise and simple, but low efficiency and expensive) to servo motors (clever control needed for precision, but high efficiency and cheap).

How far away is RepRap from producing complex electronics like a mobile phone or an MP3 player, or glass and metal objects?

If you want 90 percent of a mobile phone or MP3 player, and are prepared to buy the other 10 percent (essentially the chips), then pretty soon (maybe four years at a guess). Ten years to being able to do the lot.

Glass needs high temperature, of course, so that'll take a while. But the electrical conductor we'll be using is a metal. It's called Field's metal and it melts at 60 degrees C.

Is the Darwin 1.0 design ready for anyone to access and build their own RepRap?

Companies are already selling kits. The design isn't quite finalized yet, but is close enough that hackers are happy to build one in the knowledge that they won't have any major changes to make when we do our first official release. The machine works at the moment, and as it can make parts for itself it is particularly easy to upgrade...

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RepRap: An open-source 3D printer for the masses