Designing the perfect coffee filter

the able brewing story

Keith Gehrke, co-owner of local Portland coffee shop, Coava, was home one morning attempting to brew with his manual drip Chemex Coffee Maker when he realized he was out of paper filters. So began the hunt for reusable filters, a hunt that ultimately led to the design of the KONE coffee filter. Keith partnered with Sherpa Design to create this successful consumer product.

In 2018, when the business evolved (now called Able Brewing) they once again turned to Sherpa for their consumer product design. This time the goal was to expand the filter line, creating reusable stainless-steel filters that would bring that amazing flavor to the rest of the coffee makers on the market

_{Case study video features interviews with Able Brewing CEO, Brad Walhood, and the Sherpa team.}

Product Design Brief

The Goal: Create a flat-bottom filter basket that will work as a reusable filter in 80% of the coffee makers on the market. The design brief included the following specifications:

1. The objective of every filter is to eliminate variables to get a consistent total dissolve solids goal. In laymen’s terms you need to extract a specific percentage of the coffee in the water on the grounds. If the holes are too small, the coffee flows too slowly and is oversaturated. In the opposite case, the water flows too fast through the filter and the coffee is weak.

2. Dish washable. Naturally, customers will want to wash filters after repeated usage. Washing cannot impact the flavor and function of the filter.

3. Size variability for different coffee makers. There are many brands of coffee makers on the market all with different basket heights and widths. The design of the basket filter needed to consider variability and dimensioned the filter to work with all basket holders.

The flat-bottom filter basket that will work as a reusable filter in 80% of the coffee makers on the market — _{The basket design complete with 40,000 custom etched holes.}

This was a consumer product design challenge and at Sherpa we recognize that effective consumer product design extends beyond mere functionality. It encompasses the art of crafting a positive user experience that elevates your brand’s reputation and visibility. Exceptional product design yields items that leave a lasting impression on customers, resonating with them on a meaningful level.

Research and Industrial Design

Able Brewing started by buying a lot of filter holders from brands and sending them to Sherpa, specifying the filter needs to fit all of them. They also sent competitor samples as a reference to give an idea of their dimension solutions. The Sherpa Industrial Design team worked to define the new filter – not only the new shape, material, and size, but also the branding. It needed to be of the highest quality, reflecting that value in the design which included material choices, style, and fonts.

Solving for Taste – 40,000 holes

To get that amazing taste from the coffee, it is important to let the hot water sit in the filter long enough to absorb the flavor and bring it down into the bowl/cup.

The secret is in the unique design of the filter’s holes, all 40,000 of them. The holes are designed with etched squares on the interior wall intersecting with overlapping etched circles on the exterior wall. This creates a microscopic hole size that allows the liquid to flow through without coffee grinds. Multiple iterations of hole density were tested to verify coffee can flow through them but not too fast. Sherpa’s industrial designer ensured the holes looked good, meaning they lined up in a natural way and looked intentional.

Typically, creating thousands of features, such as holes, in a CAD model will cause the model to crash. Our mechanical design engineers came up with a solution to use trigonometry and code along with the right CAD program, Siemens NX, to achieve a product that could be manufactured.

Consumer Product Design

Sherpa developed prototypes working with Able Brewing’s manufacturer partners so they would be manufacturable within the design specs and unit costs to make the business model work. The team at Able Brewing ran lots of tests on the filter, providing feedback for any changes throughout the prototyping process.

“We have used five Mechanical Engineering firms in the last nine years. We have found that there are people who can do the work on screens, creating CAD designs that look great, but there is a difference between that and finding people who can design for actual manufacturing at a price that is feasible for small business and who can work with our manufacturing partners. That is where Sherpa Design excels.”
Brad Walhood, Principal, Able Brewing

The Filter Basket has been a huge success, received approval and is now shipping. It fits 80% of coffee makers on the market. The BASKET is now the only reusable coffee filter for your automatic coffee maker capable of brewing to Specialty Coffee Association standards.

The Next Filter

Sherpa continues to work with Able Brewing and the most recent project we were brought in on was a second filter called “number 4.” Its task is to fit the rest of the home drip coffee makers on the market. We just learned that Able hope to start production on it next month.

Designing the Perfect Coffee Filter