Ron Amundson


Because analog is cool!

Open Source Hardware and the Economy of Scale

In the software world, scaling comprises two parts, the technical aspect of whether the application will scale as users grow, and the marketing aspect. The techical part is that it wont require an exponential increase in server / computing capability, and ideally, such costs per user would drop as more users are added. The marketing part, is the marketing overhead per user drops as the application grows.. always a tricky part with any type of business, but with open source, perhaps even more critical.

In the hardware world, economy of scale also comprises two distinct parts. First, raw materials/components prices drop as the line item purchases become larger. Ie, if I want to buy one rca jack, its $2 at Radio Shack, it I want 1,000,000 of them, I can even get them customized for a fraction of that cost. Its even more dramatic with enclosures, ie getting 5 thermoformed enclosures might end up costing $500 each, where as getting 500,000 injection molded enclosures might drop the cost down to $0.50 or less.

Then there is manufacturing overhead… everyone would like to build small quantites economically, but when it comes to electronics, often times the setup costs are tens if not hundreds of times the individual piece part costs. Ie, it might take 20 seconds to populate a large dense circuit board, but it takes 4-8 hours to program, load, and test the assembly equipment the first time to make it so. A similiar deal exists in test engineering… ie, a board level test fixture costs $2500, and whether you run 10 or 100,000 units through it, (assuming one already has a lab view style master test console) the fixed costs remain the same. Lastly there is the knowledge base of the line technicians… a 10 piece run does not develop a knowledge base to allow fast rework/repair, or troubleshooting, where as a 10K run pretty much means the line techs are fully up to speed and ready to roll.

All of these factors taken together, make small production runs of open source hardware problematic. Granted, if the margin is there either by uniqueness or customization oppurtunities, its much less of a problem, but for low margin products, its a real challenge.

Some of the ways to mitigate this, are to choose parts which keep the bom cost at a minimum to start with. Ie, avoid $25 highly specific parts, even though the prices drops like a rock with volume. Another solution would include test fixture designs with the design, such that test engineering overhead is minimized. And of course, using production notes to get line techs up to speed, well before they have run 10,000 plus parts. It may be that the use of a collaborative wiki where all manufacturers can chime in with ideas, problems, and fixes may also be of great help in keeping the economy of scale manageable for low volume production runs.

Production Ready, Enthusiasts, Concepts and Production Notes

Within the open source hardware domain, there is a wide range of approaches, everything from conceptual designs, not far from the lunchtime napkin, all the way to production ready. Granted, a full blown design with gerbers, bom, avl, mechanicals, production notes, including pick/place targets is easy to spot, just as scans of ideas off napkins or notebooks, its really the projects in the middle that are hard to make the call upon.

Granted, if one is going to build 1, or perhaps a hundred, pick/place targets are likely not of great value, but production notes often are.. and often times, they are the most critical. Ie, things like ferrite beads, and the key role proper temperature profiles play, or perhaps issues like potting, and how to prevent it from migrating into the connectors etc.

And production is really where the rubber meats the road so to speak. Back in my contract manufacturing days, it was often said, most anyone can build one, the challenge is building volume, and indeed that is all too true. It could be production tooling, calibration, test selects, final test, qualification, rework, common failure modes, or any number of factors. A few pages of notes can make the difference between great success, or huge frustration and potential failure.

Thus, as I start posting designs, I will be sure to include production notes, even things that should be obvious, ie the ferrite bead issue is just one of many.