The 3D Printed Wheelchair Hand Drive Is an Elegant Solution to an Expensive Problem
Rapid prototyping and 3D printing have opened the world of product development to a community beyond professional engineers and designers to include a range of smart people with helpful, if not necessarily lucrative, ideas.
As a result, a pair of brilliant and dedicated designers have created a wheelchair attachment meant to allow any wheelchair to be powered via a rowing motion, and the piece is 3D printable, open source and consequently, available to anyone in need. 
Kate Reed is an avid unicyclist and a street performer at Faneuil Hall in Boston, MA, and Nathaniel Tong is a competitive fencer and entrepreneur who has started two businesses on the strength of products he’s made himself.
Their Hand Drive wheelchair attachment is a finalist in the 2015 Best Product category on Hackaday.
The wheelchair hack is an answer to the expensive lever-powered wheelchairs they saw that retailed anywhere from $2,000 to $10,000.
Rather than take on the task of completely redesigning the wheelchair, the pair sought to make such lever-powered wheelchairs more accessible to everyday users. The resulting attachment is almost entirely 3D printable – and costs only $40 to make.
Their Hand Drive wheelchair attachment can be attached to any wheelchair and lets the user make a rowing motion to bring the larger muscle groups into play.
It features a dual ratchet mechanism where one ratchet is engaged by a spring to move the wheelchair forward as the handles are pumped, and to move backwards, a user simply squeezes the brake on the handlebar. That disengages one ratchet and engages the other, and the wheelchair moves backwards.
Reed and Tong say the open source design of the Hand Drive means it can be customized for the needs of an individual user – say a child with smaller hands – and each piece can be adjusted to fit.
With just six 3D printed parts, a handful of screws, lock nuts, some aluminum pole, a mountain bike brake assembly, a bicycle brake cable and a spring, the device is marvelous in its simplicity.
“So far we have been through five major prototypes and dozens of sub-prototypes. It’s been a long process but we finally feel like we are getting somewhere significant,” Reed says. “We now have three final stages of the Hand Drive, one with a single double ratchet, one with three double sided ratchets, and one with planetary gears incorporated into it. Although we have gotten each design to a high level of functioning, we are still working and still trying to improve our designs.”
One of their major goals is to work towards a design where the planetary ratchets can be 3D printed rather than milled.
They say much of their motivation came from finding that statistics regarding wheelchair users say many are unlikely to have jobs and are substantially more likely than the majority of the population to live in poverty.
While the current iteration of the Hand Drive is slow, they feel it can be made faster with improvements to the planetary gears. You can check out all their documentation for their Wheelchair Hand Drive project on the Hackaday page they created.
Have you seen any other improvements to wheelchair design which rely on 3D printing to make them more efficient? Let us know in the 3D Printed Wheelchair Hand Drive forum thread on 3DPB.com.
Ingenious 3D printed wheelchair lever makes pushing more efficient
When challenged to hack a wheelchair and build the best one possible, students Kate Reed and Stefano Pagani of NuVu innovation school and Nathaniel Tong of Rochester Institute of Technology came up with an award-winning idea. The trio developed the Hand Drive, an affordable 3D printed attachment that allows any wheelchair to be powered by an efficient lever-powered rowing motion.
Rather than reinvent the wheelchair, Reed, Pagani and Tong decided to improve upon existing wheelchair designs. The trio focused on a lever wheelchair model which uses a lever mechanism and rowing motion to move a person forward. Not only is a lever-equipped wheelchair easier on a person’s shoulders and wrists, but it also is faster than push-wheel propulsion that relies on the hands to push the wheels forward. Lever wheelchairs are efficient, but their price tag, which ranges from $2,000 – $10,000, puts them out of the reach of most people.
The students wanted to make this system affordable, so they decided to create their own lever that can be retrofitted onto existing wheelchairs. They began with a handful of bicycle parts but found the components were not suitable a wheelchair since they only allowed movement in one direction. The team went back to the drawing board and decided to create their own custom mechanism, using a 3D printer to supply most of the parts they needed.
After experimenting with different designs including five major prototypes, the trio decided to use a milled planetary ratchet with a circular detent in the middle. This mechanism allows the ratchets to engage and disengage depending on whether a user is moving forward to backward. The internal ratchets are fitted inside a plastic outer housing which attaches to a wheelchair wheel. Different housings can be used for different wheels, making the Hand Drive compatible with a variety of wheelchairs.
Because they used 3D printed parts in much of their design, the Hand Drive only costs $40 to make and assemble. The only parts that can’t be printed are the ratchets, but the team hopes to address this shortcoming in future versions of the product.
“In the big picture, one of our goals is to work towards a design where the planetary ratchets can be 3D printed instead of milled,” writes Reed, “We never want to lose sight of our goal to make the Hand Drive affordable and accessible for all.”
They also made their designs open source, enabling others to build a custom version to suit their needs and even improve upon the idea if so inspired.
Aug 26, 2015 | By Simon
Time and time again, one of the most exciting developments that we’ve been seeing with 3D printing has been in disrupting traditionally manufactured products with products that users are capable of manufacturing on their own for much cheaper than what they would otherwise retail for. Among other reasons, this dramatically brings the cost of goods down since there is little overhead in terms of marketing, shipping and the cost of manufacturing the parts through traditional processes.
When combined with how easy it is to share these open source product designs, it becomes clear just how powerful this notion can be - especially for niche-specific medical products that are oftentimes not covered by insurance and are very expensive for what they are.
More recently, this example of open source product design was demonstrated by Boston-based Kate Reed, an avid unicyclist and street performer and her partner Nathaniel Tong, a competitive fencer and entrepreneur. Together, the two developed a wheelchair hack that won the 2015 Best Product category on Hackaday - the Hand Drive wheelchair attachment.
The attachment - which aims to be an affordable replacement to the otherwise expensive lever-powered wheelchairs that retailed for up to $10K - was developed to be used with existing wheelchair designs. Originally, the pair were going to focus on redesigning an entire wheelchair, but soon determined that they could accomplish what they needed to do just by simply hacking existing wheelchair designs for an average of just $40 per unit.
“The Hand Drive wheelchair attachment can be attached to any wheelchair and allows it to be powered in a rowing motion,” explains the designers.
“This motion is better for your back, as it uses bigger muscle groups, and it keeps your hands cleaner. Because of our price point and the adaptability of the Hand Drive, all wheelchair users now have access to a lever-powered wheelchair.”
Of course, developing a polished product like the Hand Drive didn’t come without it’s fair share of design challenges, but the designers were able to implement all of the necessary features into an aesthetically-pleasing design that’s capable of being 3D printed on most 3D printers using Autodesk's Fusion 360 CAD software. Among other features, the lever system includes a dual-ratchet mechanism for propulsion - a system that involves a spring-powered action to move the chair forward and a handlebar brake that can disengage one ratchet and engage the other to make the chair move backwards.
In order to make sure that their system would work for a variety of different users, the team developed multiple prototypes to test their system in action.
“So far we have been through five major prototypes and dozens of sub-prototypes,” they explain.
“It's been a long process but we finally feel like we are getting somewhere significant. We now have three final stages of the Hand Drive, one with a single double ratchet, one with three double sided ratchets, and one with planetary gears incorporated into it. Although we have gotten each design to a high level of functioning, we are still working and still trying to improve our designs.”
In total, the team’s finished design is made from just six 3D printed parts, an aluminum pole, a bicycle brake assembly and some fastening hardware - not bad considering that they originally thought that they would have to redesign an entire wheelchair to achieve the same result.
Currently, the designers are looking to gain feedback from users to improve upon their design and make it as accessible as possible for users at all ages and income levels.
“We never want to lose sight of our goal to make the Hand Drive affordable and accessible for all,” they said.
“Wheelchair user statistics inform us that wheelchair users are very unlikely to have jobs and, partly as a consequence, are substantially more likely than the remainder of the population to live in poverty. At all ages, income levels for mobility device users tend to be low. If we can pull this Hand Drive off we can significantly improve the quality of life for many- at a price point they can handle, and with the personal satisfaction of building their Hand Drive themselves with their own specifications.”
Those interested in finding out more about the Hand Drive - including source files and assembly instructions - can head over to Hackaday.
Posted in 3D Printing Applications
3-D Printing Helped These Teens Build a Smarter Wheelchair
SIXTEEN-YEAR-OLD MOHAMMAD SAYED wanted more from his wheelchair. So he started hacking the thing.
Sayed is a student at NuVu, an experimental high school in Cambridge, Massachusetts where students learn practical skills through hands-on projects, and for one his projects, he used a 3-D printer to transform his wheelchair into something more useful. He and his classmates added a laptop tray and a canopy, and, most radically, they rebuilt the chair so that Sayed could propel it with a rowing motion rather than the traditional push.
The project is just one way that 3-D printing is remaking the way we build—and modify—the stuff we use in our daily lives. This includes everything from wheelchairs to musical instruments to guns. Using cheap 3-D printed parts, Sayed and his classmates transformed a simple wheelchair into something very different—not to mention far more valuable—and they’re open sourcing their work, so that anyone can 3-D print the components themselves.
The students didn’t invent the concept of a rowing wheelchair. It’s already in use in the GoGrit, a wheelchair designed for use on rough terrain, and by NASA engineer Salim Nasser’s Rowheels project. The idea dates back to at least 1990, says Steve Spohn, the chief operating officer of videogame accessibility organization AbleGamers. But making it easy to convert an existing wheelchair by using a 3-D printer could make this type of chair more affordable and accessible.
According to the NuVu students, each part costs only about $2 or $3 to print. The only non-printable part is a bar that can be purchased at Home Depot for a few dollars more. And that could be a big deal for some wheelchair users. “If you are someone with atrophy and the muscles you would use to push with your biceps are getting weaker, allowing for different types of movement could mean the difference between continuing in a manual wheelchair or being forced to convert to a power wheelchair,” he says.
‘Start Small, Go Big’
NuVu students attend the school full-time for three months or more, but instead of taking traditional classes like math and English, they spend their time working on hands-on projects ranging from creating animated videos to cobbling together custom robots. Each term kicks off with a one week crash-course in technical skills such as computer-aided drafting, 3-D printing, laser cutting and computer programming.
Then they are given a design problem to work on for the rest of the term. The wheelchair parts were actually part of several different projects. “Actually, I wanted to make a wheelchair that flies and go under water,” Sayed jokes. “But [my teacher] said we need to start small and then go big.”
So Sayed dialed that back to a more humble request: a better laptop tray for his chair. “I had looked for trays outside before,” he says, “but never found one that fit my needs.” Soon, he and his team started coming up with more ideas, like a more accessible compartment for storing cargo, and a canopy to protect Sayed from the elements. But the biggest idea was the rowing mechanism.
No Going Back
While more feasible than Sayed’s original idea for a flying wheelchair, the project was still rather ambitious. “Our project ended up being a very mechanical problem that none of us had every encountered before: figuring out how to make our own ratcheting mechanism,” says another student, Kate Reed, 16, referring to the mechanism that enables Sayed to propel the chair forward with each rowing motion without also pulling himself backwards when he pulls the rowing bar back towards him.
“A mechanical engineer could probably have looked at it and figured out the angles to make the mechanism work. But none of us are mechanical engineers, so we went with the guess-and-check method.”
After several tries, they came up with a mechanism that seemed to work. But when they showed it to Sayed, he pointed out that the wheelchair couldn’t go in reverse. So the students went back to the drawing board.
The Real Challenge
They ended up modifying a traditional brake handle so that, instead of braking, it switches the chair from forward into reverse. “When one mechanism is engaged you can move forward, then when you pull the brake you can switch the mechanisms,” says 17-year-old Daniel Nathaniel Tong.
Tong and the other students say the project taught them a lot about product design and engineering. But more importantly, they say, they learned to work as a team. “Before NuVu, I didn’t do well in groups, because as a creative person you always push your own ideas,” Sayed explains. “Communication was sometimes a challenge, but now I’ve learned.”
"Thank you from the bottom of our hearts, for inventing this unbelievable accessibility gadget that could make life of millions, not only for the disabled but also their carers." - Lily L.
"My name's KiHow. Currently I am messaging you from Phnom Penh, Cambodia. I saw your hand drive design project and immediately thought that this could be very beneficial to alot of people here in Cambodia. I just wanted to send you a message and say great work! I'm really looking forward to downloading the files and putting one together!" - Kihow
"Hi! I'm part of a student's group from Brazil and we want so bad bring your ideia to our country... Do have idea when you'll be able to post the project's files ?? Best Regards" - Rebecca B.
"This is great! The price point and accessibility is beyond amazing.. I can't wait to bring this back to Nepal."
- Manish B.
"This is such an amazing product! I am a wheelchair user and I struggle with back pain daily. I can't wait to try your product! How revolutionary!" - Justin C.
The Hand Drive is a finalist for the Best Product Award 2015 Hackaday Prize. The Hand Drive Hackaday page has thousands of views, and many makers have found the Hand Drive via the hackaday platform.
Hackaday Hand Drive Home Page