DfM Case Study: Introduction to the KBox

Former HDDG speaker Thomas Sarlandie discusses improving the manufacturability of his OSHW project, the KBox.

A critical step in moving from design to manufacturing is reworking a design to better conform to manufacturing processes. We refer to this as Design for Manufacturing, or DfM.

These changes might be small things like changing part numbers to target components that are more easily sourceable. Or it could be larger architecture changes that requires rethinking how a device operates. These larger changes also have ripples throughout the design, including sourcing, firmware and software. The larger the change, the larger the amount of time it takes to validate that change…but also the greater potential cost savings.

Thomas has been working on the KBox for about a year, an open source hardware device that monitors the electronics on boats. He discussed the architecture, design decisions and assembly of prototype units in a talk at HDDG14 at our San Francisco office:

This above linked talk showcased the function of the KBox design. At the beginning, it was not an easily manufacturable product. We decided to chat with Thomas about ideas on how to improve this product’s manufacturability. He described some of the costs and challenges as he moves his design forward into higher volume production:

This product also showcases the challenges of working with low volume builds: each low volume component not only has a higher piece cost, but also has overhead in terms of shipping costs and material handling times. Thomas worked with Macrofab extensively, including for sourcing a majority of the components, sourcing the PCB, board assembly and final assembly of the project box/case. Macrofab is a cloud-based prototyping service that allows designers like Thomas to create products without doing his own assembly (though he began prototyping in this manner).

Future DfM activities could include the following:

LED simplification and reduction. This could also result in a lower cost switching supply due to lower power needs.

Create a water-tight enclosure that still allows user interaction (note the encoder knob is beneath the clear Lexan).

Source a screen that directly integrates with the product (instead of sourcing a screen module)

Migrate away from the Teensy platform to a more dedicated processor platform.

Reducing the overall PCB size, which factors into case choice and also into the assembly cost at a low-run manufacturer like Macrofab.

The open source nature of this product design gives an interesting look into the space between prototype and production. This process is very rarely done in public, because commercial hardware companies consider sourcing and design information to be their competitive advantage. We are thankful to Thomas for sharing his process and we are excited to share some of these steps with all of you. This is a critical lifecycle stage of product design and we want to share more about it here on the Supplyframe Hardware blog. In the past we have written about how things change as a product goes through different lifecycle stages.

If you’re looking to explore this product more, check out the KBox, which is currently for sale on Tindie:

If you would like to get in touch with Thomas, you can reach him via his Twitter handle, @sarfata.