Turning Point in Design: Human Factors

2011 March 10

During my recent sabbatical, I was able to spend plenty of time dreaming and sketching the roaster. It was spent primarily in the Bath House on the Queen Elizabeth steaming over a 23 day period from Los Angeles to Sydney. All of my normal routine was gone, communication with the outside world was prohibitively expensive, and relaxation was readily available. On nearly every sea day, I took my sketch pad to the Bath House, listened to music on my iPad and sketched for two to four hours straight.

I started by sketching where I had left off in the design. I had already decided that the bowl geometry for the roasting vessel was the way to go. The spinning bowl needed to be held in some sort of an enclosure and I had been working on using a sphere. This was inspired by our visit to the Atomium in Brussels.

A Study of Spherical Containers for the Bowls

I then started to sketch some of the form of the complete roaster, including ductwork, housing, and other necessary components. It looked very sharp: very atomic age. At this point, I started to make estimates of the dimensions of the roaster using the the controlling dimension of the bowl being 36″ in diameter. It became quite apparent that it was going to be a big machine.

Complete Roaster Concept Sketch with Spherical Bowl Housings

A Typical Human Factors Diagram

At this point, human factors had to be addressed. Human factors is the study of the human body and how its dimensions and limitations affect how the human/machine interface functions. Originally, human factors were studied in aircraft design for the military and commercial aircraft as cockpits are an incredibly complex and demanding environment. However, designers of all kinds of products have come to realize that a quality user interface separated clever, but impractical design, from superb, useful design.

Since I am the end user of the roaster, it only makes sense that I design the roaster to fit my “human factors”. As it turns out, I am rather average in my personal dimension (girth and weight, excepted!), so the typical diagrams and dimensions work well for me. It is important to me that I be able to easily look into the roasting chamber to monitor the roasting process. I also want to be able to dump the green coffee beans into the roaster with an easy motion and retrieve the cooled, roasted beans in a way that causes not strain. All of the controls need to fall naturally into place visually and be in the perfect spot for human hands. The dimensions of the design I had just sketched were starting to dwarf human scale. The sight line into the roaster was too high and loading would require steps to get up to the correct height. The spherical containers for the bowls were the culprit. They simply took up too much room and had to be spaced too far apart, geometrically: they were space wasters and that is not good design.

Stacked Bowl Conceptual Sketch

I started sketching some ideas for stacking the bowls (the roasting bowl and the cooling bowl) to reduce the overall height to the minimum necessary for functionality. The stacking of bowls did squeeze out a huge amount of wasted space and brought the viewing height into the appropriate range.

Bowl Details Sketch with Octagonal Enclosure

I then began to sketch ideas for enclosures that would work for stacked bowls. Making the roasting and cooling process as visible as possible caused me to start thinking about a largely glass enclosure. Curved glass is very expensive, particularly if I wanted to do double pane glass to reduce heat loss and help keep the outside surface relatively cool. This lead to the idea of a faceted enclosure made of flat glass with metal dividers between the sections. An octagonal or hexagonal cross-section allowed for relatively large viewing windows and enough space at the dividers to run heavy stiffeners vertically.

Roasting System Sketched as Interlocked Octagonal/Hexagonal Columns

Given the roasting enclosure shape, I started thinking about the system. The form of the overall roasting system started to take form as a series of interlinked octagonal or hexagonal columns. The first column is the roasting/cooling bowl column. The second column is contains the blowers, burners, controls, etc. and the third column contains the chaff separator (cyclone).

This new design has many benefits and I was excited to continue on working on design details. This design does not lend itself to an atomic age exterior, so I have decided to proceed with a steampunk aesthetic, which offers much more opportunity for decorative art. The design process has many twists and turns and I am very pleased with the current direction.


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