April 16, 2013

To inventors, the "home garage" has always been a symbol of possibility-a place for tinkerers to create and innovate.

About four years ago, Russ Kappius-mountain-bike enthusiast, winner of six Masters racing titles, became obsessed with bicycle hubs. He wanted more speed and responsiveness, but wasn't sure how to get it.

He got an idea for a new hub-drive system and did a patent search. "I quickly learned that there wasn't anything out there that covered what I was thinking." says Kappius.

After working out a design for a novel oversized hub and high-performance drive assembly that would transfer more power from pedal to chain to wheel, Kappius patented the concept and began looking for a way to fabricate the parts.

But how to find an efficient, cost-effective and fast route to transfer his idea to physical product? At first, Kappius and his son, Brady (an engineer and pro mountain-biker), fabricated their hub with machines then field-testing and tweaking the design.

"Because we're a startup, we quickly learned that we needed to make design changes and get new parts to our customers fast to stay competitive," the elder Kappius says.

Then in late 2011, Kappius discovered direct metal laser sintering (DMLS), an industrial additive manufacturing ("3D printing") technology. Using 3D printer from German-based EOS GmbH they could produce parts with exact specifications and design complexity they need.

"We went from concept to bike-ready components in about a month," he says. "I've never been able to move that quickly before."

Kappius Components' hubs have been through a half-dozen design iterations, but the recent move to laser sintering has accelerated the speed of improvements. Here is his story.

"As a software engineer, I am able to change anything at any time to make the code better," says Kappius. "With DMLS, I have similar flexibility. It allows me to make small design changes and almost immediately test them on the bike. That's the beauty of the technology."

The beauty of the lightweight-yet-durable hub, on the other hand, comes from the sleek carbon-fiber shell (handmade by the younger Kappius), as well as the drive assembly housed inside it - including a drive ring, toothed inner ring, and pawls (or flippers), all made using DMLS.

The technological advance in the system comes from two developments: the oversized design - it's about twice the current standard diameter and many more points of engagement than standard designs. These two features constitute the heart of the hub's intellectual property and allow a cyclist to translate the act of pedaling into increased drive force.

When he first geared up for business, Kappius bought ready-made pawls and engineered the rest of his system around them. Once he discovered laser sintering, however, he was able to redesign the pawl itself and add a one-millimeter cylindrical basal extension, which positioned them better when they engaged.

Kappius is pleased with the results. "The tool steel is super strong," he says. "I haven't had a single hub failure. Even the big manufacturers can't say that." Bicycling magazine included Kappius hubs on the timeline of noteworthy bicycle innovations in their 50th anniversary issue in November, 2011.

Russ Kappius, developer of the Kappius hub, and his son, Brady, outside their garage-shop.(Courtesy Kappius Components)

With DMLS technology and help from a New York-based DMLS provider Harbec who supplies them parts on an as-needed basis, the father-son team assembles components in their home shop after hours and ships them out to early-adopter cyclists around the world. Production is accelerating fast for the young company-they sold about 100 hub assemblies this past year and are projecting sales of 500 in 2014.

The benefits of DMLS for the bike-hub creator? "Number one is design freedom," says Kappius. "Number two is the material strength. Three is lead time."

And then there's also the rider experience. "People just love the hub," says Kappius. "They're faster and fun to ride."



Posted in 3D Printing Applications



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Cgpando wrote at 4/18/2013 4:08:45 PM:

It is very difficult for me to accept calling an EOS Metal machine a 3d printer. I can understand that you call an Objet machine a printer because it has "printing heads". But don't create false illusions on 3d-printing, as the majority of things you are calling 3d printers are the fused filament cheap things, in the $500 to $50.000 and none of them will ever be able to "print" this high quality Al parts for a hub.

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