Source Code

The primary inherent advantage of an Open Source unit, which is also modular and designed to use common, widely available parts, is that it can be economically maintained over the long term.   All components used are easy to replace and can always be sourced, in the near or distant future, from many different suppliers. 

Because the parts can be sourced from suppliers other than the original manufacturer/designers, the incentive to engage in planned obsolescence is broken.  

Additionally, there is no need for the company to stay around for the very long term in order for the unit to continue operation long-term.  70% of companies in the business of home improvement products are out of business within 10 years, and 50% are gone within only 3 years.   Long warranties are therefore useless anyway.

It is important that building elements be effectively maintainable over the long term to get a good return on investment.  Buildings are a long-term proposition.

If a unit lasts 30 years instead of 5 years, that means it's average cost of operation is 1/6th as much, per year (even less, if you  factor in interest).  This has a major impact on return on investment.  The OpenERV has only one wearing part, the bearings, and they can be replaced easily.  Therefore, there is almost no natural limit to how long it can last, because anything that wears out or is damaged can always be replaced.

The use of additive manufacturing and open source components is also no philosophical matter.  In order for components to be easily obtained by many suppliers, they are both necessary.  No machine of this kind can be produced without a few custom mechanical parts.  The only practical way to make such custom parts widely available from someone other than the original manufacturer is to use common additive manufacturing processes and publish the digital manufacturing files.

There are actually more parallels than is widely realized between software hardware, regarding the marginal costs involved and how things are done.  Using a supposedly free piece of software is not free, because you need to invest to learn to use it, get it working, and whatever you use it for entails other things becoming dependent on it, which implies risking labor time if the software turns out to not be up to the challenge.  However, the "compiling" process is very different - the "source code" of most manufactured objects is of little use except to aid repair, like a manual, because the manufacturing of any part from "code" has large capital costs.  Even if you have the design of a component, you can't practically make it because it costs $50,000 to make the mold or set up the assembly line to make the component.  So you are still stuck buying it from some company that has invested that capital.  Additive manufacturing can, for the first time in history, change this.  Not only is the tooling cost (the cost to make at least one of a unique part) very low, but the actual machines are relatively cheap.  This is why it tends to be an integral aspect of open source hardware. 

Fortunately, for electronics, the ecosystem for components has a lot of good commodity parts that are widely available, and there are a lot of companies that stock them and can make you a custom board surprisingly cheaply straight from the design files.

However the limitations of additive manufacturing prohibit many types of mechanical parts from being produced.  We hobble around this, again, using mass manufactured commodity parts, like the bearings, motors, and screws.  

Some aspects of the source code are not ready yet, and publishing partially completed stuff has no real value in this particular context.  But, it will be here:

The STL files (zip file) are ready now.  (unfortunately Github does not support files of significant sizes, I am looking for better persistent hosting options).

Micropython source code packages (you can also get this directly off of the Raspberry Pi Pico built into a unit):

Electrical schematic (there is a copy in the manual, too):

There is a list of replacement parts and their part numbers etc. in the manual.


The TW4 is open source, with all files and the firmware licensed under the CC BY-NC-SA 4.0, which allows non-commercial use without a license.  If you want to make and sell them, talk to us first.  The source code is provided for the purpose of enabling maintenance and as part of the strategy to eliminate the incentive for planned obsolescence, not to enable cloning of complete devices.  If you would like to print your own unit, we can come to an agreement.