Meticulous Bionic Hand

[Will Cogley] is slowly but surely crafting a beautiful bionic hand. (Video, embedded below.) The sheer amount of engineering and thought that went into the design is incredible. Those who take their hands for granted often don’t consider the different ways that their digits can move. There is lateral movement, rotation, flexion, and extension. Generally, [Will] tries to design mechanisms with parts that can be 3D printed or sourced easily. This constrains the hand to things like servos, cable actuation, or direct drive.

However, the thumb has a particularly tricky range of motion. So for the thumb [Will] designed to use a worm geared approach to produce the flexing and extension motion of the thumb. These gears need to be machined in order to stand up to the load. A small side 3d printed gear that connects to the main worm gear is connected to a potentiometer to form the feedback loop. Since it isn’t bearing any load, it can be 3d printed. While there are hundreds of little tiny problems still left to fix, the big problems left are wire management, finalizing the IP (Interphalangeal) joints, and attaching the whole assembly to the forearm.

All the step files, significants amounts of research, and definitions are all on [Will’s] GitHub. If you’re looking into creating any sort of hand prosthetic, the research and attention [Will] has put into this is work incorporating into your project. We’ve seen bionic hands before as well as aluminum finger replacements, but this is a whole hand with fantastic range and fidelity.

Thanks [Johnathan Beri] for sending this one in!

12 thoughts on “Meticulous Bionic Hand

  1. Yet another failure to use 3d printing properly.
    You don’t design a finished thing to be printed.
    You print a thing to test how works in the physical world.

    Prototyping and Art. That’s what 3d printing ‘is for’.

    1. You are so very wrong. The boom in rapid and high quality 3d prints mean they are getting into real products everywhere. Its one heck of alot cheaper to pay any ol’ meatsack to set a print farm going and do any post processing on a small part run than it is to pay for a real machinist and all the iterations to make great injection molds for example..

      So you really should think about designing things to print, often for smaller scale its way way cheaper and therefore profitable to 3d print. But to get easy and reliably good prints you want to design to suit the machines you have as well as possible!

    2. I am fairly sure you are trolling here, rather than expressing an actual belief, but I’ll bite.

      In the real world, you absolutely do design with the material and the manufacturing process in mind, including the benefits and the limitations.

      Fifteen to 20 years ago, your statement still held some water, and to a point does at the bottom end consumer grade FDM level. But even the $US200 machines are good enough to give what is needed in most design scenarios: reliable dimensions, repeatability, predicable properties, and consistent quality.

      Think about the changes when powdered metal processes became available, and the advances over the last forty years of so in that realm. Early use-cases were limited to lower strength parts with lower tolerances. Final dimension was often nonuniform over a part and surfaces could vary a good bit as well, but, with appropriate design consideration, long lasting parts that were impractical to machine economically were turned out by the million- bevel gears in machine tools, for example. Expensive machined gears were the norm when I was a youth and the price of the tools showed it. In the late 1970’s, a handheld angle grinder was an expensive unit. Prices dropped a LOT during the 1990’s as powder metal processes improved and the machined gears were replaced in these products. The gears are not the same. Redesign occurred, as the PM gears at the time had reduced impact strength, significant porosity, somewhat lower fatigue strength, and lower overall strength, relative to the machined gears. But there were also advantages in lower net cost, due to little machining needed, and the PM gears can have advantages with lubrication. Material can also be tuned for an application. There has been a lot of improvement, and now, you can do powdered metal 3D printing for a moderate price and get your very own metal 3d printed parts. Handy.

      If the strength of the titanium part isn’t needed, but only the strength of PLA, and the dimensional tolerances of a 0.25mm nozzle FDM print are suitable, design for it. The titanium part might be smaller, but it will certainly not be cheaper.

    3. 2001 has called and wants you back. Those days are over. I say this as a mechanical engineer with 20 years of 3d printing experience. End use parts are very doable especially with materials that bond well out of plane.

    4. When it comes to prosthetics, customization is an important factor to account for the wide range of sizes and shapes of human bodies. Professional grade 3D printing can help.

      If the hand is built for a robot, then maybe standard off the shelf sizes could be used to take advantage of other manufacturing methods and their economies of scale.

  2. Little typo here:

    If you’re looking into creating any sort of hand prosthetic, the research and attention [Will] has put into this is work (*worth?) incorporating into your project.

  3. My biggest phobia is losing a hand or finger(s). I’ve got a habit of noticing when someone is missing a finger. Then ask how they lost it, so I can bank that info to save my own.
    Had a customer with a BeBionic prosthetic hand and it was the coolest thing I had ever seen. A beautiful work of art of you ask me. I’ve shook hands with an astronaut, artists, musicians, authors… But that guy was the coolest hand I ever got to shake with.

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