On the Cutting Edge of Technical Knit Manufacturing

Ruth Grace Wong
Published in
9 min readApr 22, 2019


Connie and Bruce Huffa are Fabdesigns Inc., the engineering firm behind pioneer products such as the Nike Flyknit and Warp Lacrosse Racket.

Connie speaks about how knit-tech engineers can eliminate waste, improve recyclability, and bring industry back to sustainability, while also making better products with higher profit margins.

Bruce Huffa stands in front of their Stoll ADF knitting machines at the office of their textile engineering studio, Fabdesigns. ADF stands for Autarkic Direct Feed, meaning that the yarn feeders are individually controlled.

A Mixture of Older and Newer Technologies

In 2013, Americans produced over 15 million tons of textile waste, and 85% of it went to the landfill. “I bought a 200 year old house, and all the closets in it are really tiny! Back then people had maybe two outfits for work, and one outfit for dressing up — they just didn’t have as much stuff.” As a veteran of the manufacturing industry, Connie is keenly aware of how mass production technologies have enabled mass environmental pollution.

“I got started in this industry when I was 19. My husband started when he was 16. We grew up in the factories.” When Connie started her career, mechanical knitting machines were going out and computers were coming in. She first started on a Shima Seiki machine. “The guys let me do it because they thought that the computerized machines were just a fad.”

Connie keeps an old Apple 2 computer in her office, “because there are some factories in India that are still using this really old technology, second hand.” She shows me an old metal punch cylinder, reminiscent of how the old IBM mainframes were coded. “We used to have to punch tapes, because the machines had no RAM back then.”

She and her husband are at the cutting edge of their field, partially because they still code in machine code, and can find ways to manufacture more efficiently and effectively than everyone else using the graphical user interface. Bruce’s teacher was Thomas Stoll himself, and Bruce was the instructor for Stoll’s North American office back in the 80’s.

Connie knows all the machine language color codes by heart and rattles them off to me. I ask her if it’s possible to break the machine because you don’t have the safety mechanisms that using the software’s visual interface gives you, and she tells me about a time when she forgot to change the tension and broke 200 needles ($4 each) at once. “You have to wear glasses,” she taps hers and grins. Even with today’s What You See Is What You Get software from the machine builders, it’s still possible to make a tension mistake, although the software flags most other issues before they happen.

Top Left: Apple 2 computer in Connie’s office, because sometimes they work with factories in India with old second hand equipment. Top Right: Old school data cartridge. Bottom Left: An old printout of knitting machine code. Bottom Right: Hardware for programming knitting machines with the punch-card method.

The Innovative Solutions From Fabdesigns

Connie and her husband Bruce are Fabdesigns: an engineering firm that takes product ideas and builds complete manufacturing platforms, including training the factories on best practices in lean manufacturing processes. She explains to me that “each yarn feeder is allocated to a system, and on the ADF [Autarkic Direct Feed] we may have multiple feeders in each system”.

You can knit a 3-color jacquard with multiple colors, choosing which colors you want to see on the surface and which to place on the inside of the fabric. For more than a 3-color jacquard fabric, the machine makes multiple passes to create each layer in a row of fabric.

If a machine has two needle beds, you can knit tubes based in jersey fabric only, but if your machine has four needle beds, like the 530 MTB machine in Fabdesigns studio, you can do double bed transfers. This means that you can move and manipulate the knitted pieces in the machine. Both Shima Seiki and Stoll machines utilize 4 needle bed techniques to create garments in one piece without any cutting or sewing.

Left: Stoll 503 MTB four yarn ‘systems’ hang from a the left side of a knitting machine. The ADF (Autarkic Direct Feed) machine sitting next to it can use up to 32 of it’s feeders in a fabric. Right: Several generations of knitting machines sit in the Fabdesigns office, to be used for prototyping and development for factories all over the world.

Three dimensional knitting technology has been around for a long time — since the debut of the Stoll 400 and 402 machines at the 1987 ITMA in Paris. Connie and Bruce have the old brochures on the wall in the studio. Bruce moved from Smitex, the Stoll agent in the UK, to Stoll America in 1985. In 1987 they both helped Stoll pioneer flat knitting on the West Coast through technical sales, programming service, machine installations, and machine services for Stoll.

Bruce and Connie Huffa in front of their 33TC machine

When they got engaged, they were forced to go on their own by Stoll, and subsequently started their own company. Fabdesigns has been in business since 1988, and has always been focused on the most technically difficult projects, knitting to shape, and supporting manufacturing facilities in the US, Mexico, Canada, South America, Asia, and around the world.

The systems they’ve built focus on making products that sell as efficiently as possible. They enable savvy designers from big brands and start-ups to customize fibers and structure placement for function and aesthetics.

Connie tells me about how she’s been recently excited about thermochemistry and other unseen inks that change color based on the environment, because that opens a whole new host of possibilities for knitted technology.

Her machine knitted samples include everything from pieces that have glue yarns in them (This yarn was developed in the 50s), fabric knitted with integrated pockets, padding full of little clear curls of knitted nylon that act like springs, and structural knitted pieces like cables and braids.

Left: Warrior Sports Lacrosse 3 dimensional racket head with Kevlar rim in the knitting. Right: You can knit a sphere.
Left: Spacer fabric that can be used for medical purposes. Middle: Fabric with padding knitted in the form of nylon coils. Right: Knitted straps and flip-flop uppers.
An example of an expandable and collapsible 3 dimensional knit structure

In a previous article, I wrote about just in time, custom-made manufacturing, and it turns out that from 2001 to 2010 Connie and Bruce were working with Brenda French of French Rags to manufacture made to order. “It’s all been done before.” They are currently working with Variant to streamline on-demand manufacturing, where brands or individuals can use an online platform to upload their own artwork onto garments and products, which are then fed directly to a knitting machine for production.

Bruce wrote software that basically takes over from where the online customizing platform leaves off and uses machine language to queue up each order sequentially, one right after the other for Variant.

The Limitations of Knitted Products

I ask Connie about the design limitations associated with knitted products. “Flat knitting is slower than circular or warp knitting, but far easier to set up. In flat knitting one can add or drop needles, creating real shaping and dimension. Only in flat knitting can true seamless products be made with no cutting, no sewing, and nearly zero waste.

One of the issues with knitting in general is that in jacquard fabrics with strong colors, say black and white, there can be grin through. This is where you can see the other colors of a knit jacquard peeking through the surface color via holes in the fabric.

Some designers don’t like this because their ribs are a solid single color and vivid. The introduction of other colors creates a muddier look. The only way around this is intarsia. Intarsia can be employed to prevent grin through, where one yarn feed stops and another picks up where it left off, but this technique leaves ends in the middle of the fabric. It also costs about 25 cents to process each end.”

Another limitation is the number of colors. Connie says that for colors, there are a maximum of 32 feeders, so you can’t have more than 30 yarns because of the need for a draw thread and a special elasticated thread for the takedown comb on the machine.

Left: The green and red ‘grin through’ the black on this jacquard. Right: ADF (Autarkic Direct Feed) machine with 32 yarn feeders.

Eliminating Waste Wherever Possible

Fabdesigns works on technical knits, which is a lot different than working with the fast-paced seasons of the garment industry. “It can take three years or more to develop a medical device, 10 years for a plane, and about 1.5 for the interior of a car — if the design doesn’t change. Then, the products are manufactured for 4–5 years in the case of automotive, or even 15–20 for a medical device.” At this scale, the effect of engineering efficiency is exponential. It’s imperative to keep as much out of the landfill as possible to decrease the carbon footprint.

In cut and sew manufacturing it’s not uncommon for 20–30% of the fabric to be wasted. With wholly knitted manufacturing, which is what Connie specializes in, there’s nearly zero waste — only the waste yarn at the beginning of the piece.

Stoll M1+ CAD system

“We need to think ahead. What’s the exit strategy?” As Connie works on developing fabric with metal in it, she’s also thinking about how that fabric is going to be ground up to extract the metal for recycling after it’s been worn out.

Exploring Potential Recycling Solutions

She mentions a few companies that are all in the textiles and recycling space: Bionic, Tepar, Repreve (fabric from plastic bottles), and Recover. “I really like what Recover is doing. They’re taking clothing that is past production, sorting them so that all the same fabrics and all the same colors are together, and recycling them that way.” In these systems, the black, red, and green jacquard sample that Connie has would go in the black pile to be recycled.

“For some technical knits the specifications would be too exact for recycled fiber to be used, but for most applications in the garment industry, recycled fiber should be fine. The difficulty is that often with recycled material there is no color guarantee. Consumers have to realize the limitations, and designers need to realize how much we can use recycled products and close the loop. It might be a little higher in price, but what is the price of not recycling? People are going to have to vote with their wallets.”

A room in the Fabdesigns office with samples on the right and oaktag patterns in the back.

Connie reminisces about the first light up shoes made by Sketchers that she bought for her kids. They had mercury switches in them. The company was responsible and provided a mail in envelope with every pair, so that consumers could send in their used shoes. Mercury is regulated by the EPA as a hazard in landfills, but with the globalization of commerce now, the logistics of individually sending used products to one place don’t make sense economically. Perhaps large companies can make a difference — Connie mentions how Walmart started in 2009 to require its vendors to state how much recycled content is in their products. For instance: how many bottles were actually put into a specific product.

“My grandmother used as much plastic in a month as we do in a day,” Connie says. “We took soda bottles back to the store. It’s only since the 90’s that companies have shifted the recycling problem to consumers. Interesting isn’t it? This is the same time they shifted production off-shore.”

From recycling plastic into textiles to developing new color matching technologies for recycling fabric, it’s up to today’s engineers to reverse our environmental debt for tomorrow’s planet.

Thanks to Connie Huffa for inviting me to her office to interview her, and going over this article with a careful eye to fact check and add important details. If you are interested in partnering with Fabdesigns for a product or interning with them to get into the knit technology industry, you can contact Connie and Bruce at http://www.fabdesigns.com/.



Ruth Grace Wong

Pinterest engineer by day, manufacturing engineer by night. Manufacturing writer for https://medium.com/supplyframe-hardware