Using Metal 3D Printing to Make an Innovative Bike Part

EOS GmbH is the market leader in metal and plastic powder bed fusion systems. Also called selective laser sintering, laser sintering or SLS. The metal variants are called Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM), Laser Melting and many other things. These industrial 3D printers are high throughput manufacturing solutions. I’m personally a massive fan of SLS as a technology, and my dream desktop 3D printer is a Formiga P110. I tend to think in SLS when I’m developing something with someone. It is the most predictable technology and easy to price in as well. EOS is also a good company with a strong long-term vision and values. Employees have tenure with the company staying with them 10, 12, 14 years or more. I’ve worked with their equipment for nearly a decade and recommend it to clients. So yeah, I thought I’d give you a heads-up on my biases. Feel free to send me your company’s 3D printer in an attempt to convince me that it is better than a P110.

DMLS works when a metal powder is spread out in a build chamber with an inert gas in it. A laser sinters the powder that will become your part and unsintered powder remains to support new layers. A new layer is applied, and the process repeats. Due to the thermal stresses on the part during this process, supports have to be designed and removed. Getting a completely new geometry to print is often difficult the first few times. Similar geometries do print well which is why DMLS has been used to print tens of millions of bridges and crowns and tens of thousands of orthopedic implants. After parts come out of the machine, they often go through a series of post processing steps which may include tumbling, EDM or shot peening. DMLS is the only 3D printing technology suitable for making fine mechanical metal parts and high tolerance metal parts. On the downside you can only run these machines in an industrial set up with HVAC and the works. Compared to DED or other metal technologies, build volumes are limited. Part cost will be higher than with ExOne and often higher than 3D printing + casting, but this depends on a number of factors. Development time of parts and time to part is higher than FDM for example. DMLS/Powder Bed Fusion is ideal for aerospace, medical and applications where you need to make thousands of parts a day. The initial investment is considerable as are running costs. So an excellent technology for individual parts at high volume.

Kappius Components is a Boulder, Colorado based bike component manufacturer started by a father and son team: Russ and Rob. Both bike enthusiasts and engineers, they attempted to manufacture their own bike hubs. The hub is the spinny spin thing at the back in the middle of the wheel. The Kappius’ hubs were more efficient and transferred more power. The team, however, was not able to make them efficiently. Lead times were too long or the parts were not good enough. And what happened next kids….can you guess? Gather round my children because they….turned to 3D printing to solve their problems. And all the problems went away and everything was magic. I guess you can only read so many white papers before you go just a little bit mad. I mean don’t get me wrong they’re fine usually, but there’s never any drama.

Black Papers

Black papers would be so much more exciting…
Initially, the Xcorp team was very skeptical of YStartup’s wild claims and promises. This was exacerbated when they clearly had no knowledge of the insurance industry, were overpriced, arrived late at meetings, look disheveled and offended senior management with loutish behavior. Glad to be spending time with younger people who had “the social medias” Xcorp nonetheless persisted in working with the white tennis shoe wearing kids. Not only their buzzwords were the prettiest. A late night drinking session at a trade fair between recently divorced Simon and comely Amanda made Simon a weary champion for YStartup. An alliance between the two firms was only formed however when Xcorp VP Lucas outmaneuvered another VP Amanda, hoping to make her lose her famous volcanic temper publicly in an IT Compliance Gold Circle Meeting in front of CTO Mary. By suddenly announcing an alliance with YStartup he caused Amanda to crush her six shot Trenta Maple Pecan Late and drown a Polycom Soundstation1. Join us again next week on Black Papers for more corporate intrigue, backstabbing, and careerist psychopathy! Will Lucas win by securing a budget raise? Will Amanda secure her future by diverting a contract to a former intern? Will Tom’s fake homosexuality gambit be enough to gain him entry into the coveted High Potential Pool? Or will he have to go further to succeed? Perhaps even masquerading as a transgender? A new installment of Black Papers arrives Monday!

Kappius Components’ best in class 3D printed bike hub assembly has been under development since 2011. The oversized hub design was able to be redesigned due to DMLS and is produced by Harbec, a service bureau in Ontario, New York. In addition to 3D printing, the part is CNC’d and then heat treated. The company is now able to go from their idea to a part in a matter of weeks. Russ Kappius explains that, “We went from concept to bike-ready components in about a month.” He says that “The essential asset is design freedom. Number two is the material strength closely followed by the lead time.” They were able to iterate their designs quickly and go to market quickly because of 3D printing and are still improving their hub.

The paper goes on to explain just what is so unique about the hub design:

“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. While the most standard drivetrains have 18 to 36 points of engagement, the Kappius hub is built around a drivetrain with 240 points of engagement. So the pedal can engage every one-and-a-half degrees and give the rider an extra quarter- or half-pedal stroke. These features allow a cyclist to translate the act of pedaling into increased drive force which is great for racing and highly technical riding.”

Another thing that seemed exceptional was something I encountered on another site about their workshop. It shows how they take SRAM cassettes and hollow them out to adapt them to their designs (which is a shame since SRAM isn’t great). It also shows how “these neodymium pawls are 3D printed with a magnetic inside which acts as a spring.” Now printing neodymium on a DMLS machine would be rather complicated. It’s also kind of semi-impossible to find out if there is any emerging research on that because DMLS machines use YAG lasers and these are “neodymium-doped yttrium aluminium garnet” lasers. So its difficult to tell if there would be some super amazing breakthrough in this area. There are research teams working on metal printing magnets directly for aerospace applications and missiles but I’m guessing that here the part was printed and then the magnet was added after the fact? This is quite a nice part however and could be a good showcase how relatively small well made parts can play nice with more standard parts in assemblies.

The parts are built on two M270 metal printer builds and the company has sold over 500 so far. The hubs cost $700. The team chose maraging steel as a build material. This is just the kind of innovation that we want to see in 3D printing. Small innovators taking advantage of this technology to level the playing field with the production of actual parts. Agile engineering whereby designs are continually improved based on real-world testing and feedback in combination with 3D printing means that companies are more competitive and lean. It’s companies such as Kappius that will through being new entrants penetrate new markets due to 3D printing.

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