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The OPP T-Hook in Scientific American · 18 September 08 by Jonathan Kuniholm

For those of you who haven’t seen it, our efforts to improve on the well-loved features of the out-of-production Trautman Hook have been profiled in Scientific American Magazine this month. In order to avoid any possibility of confusion with the old Trautman brand, we’re going to refer to our new and improved design from here on out as the T-Hook.

Unfortunately, no one has as of yet stepped up to do something with our design to get it in production. We’d love for that to happen, but we’re still working on the design, and the business case is still not strong enough. If you’d like to be included in any possible clinical trials of the new T-Hook, please send an email to info@openprosthetics.org, and put “Want T-Hook” in the subject line. We’ll let you know if we hear that someone’s going to give it a try.

You can check out all of the projects that we have going on our wiki page, including the T-Hook page, where you can download all of the CAD and rapid prototyping files, as well as follow a link to the CAD file viewer.

If you are an amputee, prosthetist or prosthetic technician, you can let us know what you think through our three surveys. We’re calling it a census, because we’d like to hear from everyone.

Connect to others on our social net, our community for users and volunteers. We’ve applied for access to Google Friend Connect as a way to make all of this a little more seamless, but haven’t heard back yet.

As you may have gathered, we are using a collection of free and open tools to make this happen, and it’s not perfect. If you are a master programmer and looking for a challenge, we’d love for someone to help us build a fantastic Sourceforge-type project management and collaboration tool with social networking capability, as well as the next generation of collaborative open source CAD tools to drive this and other open design projects. Until then, we’ll do with what we got.

Thanks for your interest, and we’d love for you all to jump in on the wiki, use the social net to connect with each other, and get to work.

Jon Kuniholm

Blog Posts from OpenProsthetics.ning.com · 17 January 08 by Jonathan Kuniholm

We're Looking for a Few Good Ideas · 10 January 08 by Jonathan Kuniholm

Lead users are consumers (individuals or companies) who spur innovation in an industry by contributing innovations often of a greater value and at a faster pace than the companies that produce the products they use. Their innovations are often freely shared and eventually incorporated into products. Far from being an idealist fantasy, lead user innovations can be incorporated into the R&D strategy of a nimble company, enabling quick identification and anticipation of consumer needs. What we’re trying to accomplish through the Open Prosthetics community is to facilitate this phenomenon, well-described in MIT Professor Eric Von Hippel’s book, “Democratizing Innovation” (downloadable free from his website or ours).

Innovations by amputee-users are very important in the history of prosthetics, notably by folks like D.W. Dorrance, designer of the early split hook, versions of which remain the most popular arm terminal device today; Bob Radocy, whose innovative grip and sports devices are sold at TRS ; and Dr. Hugh Herr, developing powered ankles in his lab at MIT. Perhaps less well-known but equally important are the prosthetists and technicians who have innovated for their patients over the years, contributing products and custom modifications for their patients, some of which have entered common use, and others which have not.

Join us at The Open Prosthetics Project, in assembling the core group of active innovators that the project needs to help us reach the next level in innovation. We have established a social net to allow direct connections, and a wiki including descriptions of active projects that can be freely edited. Contribute to an existing project, or start your own. Please download our flier, asking for help finding lead users, and post it where you see fit.

New Tools for Collaboration · 7 November 07 by Jonathan Kuniholm

After several months of hoping that we could figure out how to effectively manage the spammers on forums of the old Open Prosthetics site, we’ve given up, moved the forums to a new Google Group, and are trying to get up and rolling again. We’ve added a couple of free tools from other websites to help with collaboration.

Our new social net on Ning allows volunteers, users, and anyone who is interested to make direct connections and is, we hope, the magic bullet that will free everyone from being choked by our in box.

We’ve established a wiki, that you can participate in editing. Check out all of the new projects there, and consider discussing your ideas for new ones.

The Google Group duplicates some of the information available elsewhere, but also allows broadcast communication for those who like it.

Please let us know how things go, and we’re hoping these new tools and features get the Open Prosthetics community functioning in a way that we haven’t so far.

"Trautman-Style" OPP T-Hooks Delivered; Lego Hand; MMG · 15 April 07 by Jonathan Kuniholm

We’ve completed four more “Trautman-Style” OPP T-Hook prototypes, and donated them to longtime users for evaluation. We’re told that one, a retired welder, had repeatedly repaired his hook himself until, after 15 years of repairs, it was no longer salvageable. A more detailed update is available below.

John Bergmann, a volunteer, has completed a very cool LEGO extrinsically actuated hand. We’ve put a more detailed update in the mechatronic arm project section, where you can download complete instructions for constructing the hand. We’re working on a way to actuate it. Please consider building one and coming up with something.

Jorge Silva, a PhD student at the University of Toronto, has put together some great instructables on our group page explaining how to construct sensors for acoustic myography (MMG), or the measuring of the sounds made by muscles when they contract. The page also has some activity on a couple of other topics.

"Trautman-Style" OPP T-Hook Update · 15 April 07 by Jonathan Kuniholm

We’ve had four more prototypes made of the “Trautman-Style” OPP T-Hook by Rapid Tool, Inc. The folks there were very helpful getting what we needed done, and we ended up with two each left and right hooks in their ST-100 bronze-infused stainless material, which we are confident will be strong enough for daily use. The design changes Jesse made, coupled with the stronger material, should eliminate the common fractures we have seen on a lot of older hooks.

We had much better luck with this batch than with the previous metal process we tried, and dimensional tolerance issues with assembly were minimal. All of the prototypes were usable after tapping, threading and, in a couple of cases, a little filing. Because the build process involves building some of the parts on a scaffold, the surface finish resembled a clean sand cast on some parts and a brushed sanded surface on others. We may explore powder coating or chroming the material if users are interested. This will require adjusting the dimensions to account for the added surface material.

Because we’re still working out how to get these made and distributed, we were happy that Tackle Design was willing to donate the prototyping costs, and we provided the hooks free of charge to four longtime users of the hook in Minneapolis and Sartell, MN; Lacrosse, WI; and Seattle, WA.

Once these users have had a chance to try and break their new hooks, we’ll see if there are further changes that need to be made to the design. We are exploring ways to get the hooks made and distributed as cheaply as possible, and will keep everyone posted on these developments.

Pimp My Arm; More Media · 10 October 06 by Jonathan Kuniholm

We are in the process of expanding the site as promised to allow users and volunteers to exchange ideas in a dynamic forum called Pimp My Arm. The recent media attention, including a brief interview with Scott Simon on NPR , an article in Wired News and a Slashdot Post has generated a lot of ideas and volunteers. My apologies to those we haven’t gotten back to yet. Please use the new parts of the site to post your offers to volunteer, your ideas for projects, or your comments on anything. As mentioned previously, we’re interested in having people use our group on Instructables as ideas gain momentum, but the threads here can serve as the launching pad (and please link to those pages here to spread the word).

We’re continuing to work with Wyrick Robbins, our attorneys, on the incorporation documents and IRS filings for the Shared Design Alliance (SDA). The SDA will be our parent organization and will help OPP develop the infrastructure we use to publish designs, as well as aid other worthy efforts to do publish physical designs. We’ll have a more complete post on all of these details as the paperwork is completed.

In case you missed it, a stream of our appearance on Dick Gordon’s “The Story” can now be had from their archive

New Project; Radio Appearance · 15 August 06 by Jonathan Kuniholm

We had a revalation about the origin of the rubber bands used for body-powered prostheses, and have started a new project to document potential alternatives. The initial results look promising, and we’ll post more detail than you’re probably interested in as it becomes available.

Hook with black bands

On Monday, Chuck and Jon from Tackle and Robert, who is working on two projects on OPP for his son Michael, taped an interview with Dick Gordon for his show The Story , which will air this Thursday, August 17th on WUNC, our local NPR station, at 1 pm and 8 pm. We enjoyed talking with Dick, and are looking forward to sharing the project with more people. If you missed the show, and want to hear it, contact us.

OPP In the News · 14 July 06 by Chuck Messer

The Open Prosthetics Project has been flooded with visitors today thanks to robots.net and makezine.com. Robots.net has blogged about Tackle Design before when we did our DIY bomb disposal robot. We appreciate the links and welcome all of the new visitors.

The Open Prosthetics Project is moving along but since it is currently a project of passion and not pay, we are keeping the lights on with other projects and working on OPP as we have available time. Of course, you can always help us dedicate more of our time to the project by donating. We are working on getting non-profit status thanks to some pro bono help from Wyrick & Robbins, but for now, any donations you make are not tax deductible. Of course, we are as open with the finances of this project as we are with the designs and will publish all of the donations as well as what we do with the money.

At the moment we’re also working with Instructables to launch a community group to support easier documentation of Open Prosthetics innovations. Along with prosthetics technologies keep an eye out for innovations from Engineering World Health, a group dedicated to developing accessible medical technology for developing countries (see the related post for information another EWH/Tackle Design collaboration for Jaundice treatment). Thanks to the Instructables team for posting two existing EWH innovations. Similar to the Open Prosthetics group, Instructables will be hosting EWH’s documentation. We encourage other like-minded groups to consider using the Instructables platform and community to share their work. Thanks to the folks at Instructables and SQUID-Labs for all their support!

Engineering World Health Collaboration · 14 July 06 by Chuck Messer

Another open source medical project that we are ramping up in partnership with Engineering World Health has received some attention. We are assisting the winning team of the EWH Cures Competition with some pro bono design work to prepare their product for higher volume manufacturing. I was invited to help judge the competition where we selected a team to receive $100,000 in funding to start a not-for-profit business to make and distribute low-cost lights that treat jaundice.

The device, which will cast blue light onto the skin of infants, helps turn bilirubin, a harmful chemical that is not handled well by the liver, into a more harmless one that can be safely processed by the body. Tackle Design is working with the contest winners to take the design to final implementation and will host a small-scale manufacturing effort with volunteer labor to produce some of the devices to distribute to the developing world. Please contact us to find find out more about the project or how you can participate.

Prosthetic Fishing Rod · 9 June 06 by Jesse Crossen

Robert Haag has started another interesting project for his son Michael: a prosthetic fishing rod. The idea is to attach the rod as a terminal device on Michael’s prosthetic arm in place of the usual gripper. Pretty much anything can be made into a body-powered terminal device by attaching 1/2-20 male threads to it, although it’s a little harder to make it do something when you pull the cable.

The first stage of the project is to modify the rod so it can be attached as a terminal device. Below are the parts and the resulting device:

parts for the prosthetic fishing rodassembled prosthetic fishing rodthe prosthetic fishing rod attached to the wrist

And here’s a video of Michael practicing his cast:

Video of Michael practicing with his prosthetic fishing rod

The following supplies were used:

The rod’s handle is trimmed about an inch from the base, then the inside is built up with hot glue and the knurled plate is super-glued into that. The joint is then sprayed with red Plasti-Dip to hide the imperfections. The washer keeps the rod from rotating when it’s screwed into the wrist. The next step is make the cable push the release button for smoother casting. Stay tuned for more detailed instructions on how to make your own prosthetic fishing rod.

Partnerships · 11 May 06 by Jonathan Kuniholm

Bob Radocy of TRS Inc. has partnered with us to explore possibilities in the commercial offering of open source designs, and may collaborate with us on some projects. As a businessman, designer and user of prosthetic devices, Bob has quite a broad perspective on the state of upper-extremity prosthetics, and has done a lot to change the options available.

A note we forgot to post from some time ago: Ralf Hotchkiss of Whirlwind Wheelchair International has agreed to help us with his expertise in open source design and appropriate technology. Ralf has been involved in helping small businesses in developing countries manufacture low-cost wheelchairs using local materials for over 30 years. Ralf’s design is sturdy, reliable, and suitable for the environments in which it is used.

Pediatric Trainer · 7 April 06 by Jesse Crossen

A few weeks ago, Robert Haag contacted us with a very interesting idea. His two year old son wears a body-powered gripper, and they’re trying to teach him to use it. It’s a pretty complex skill because depending on where the gripper is positioned, different combinations of shrugging motions are required to open and close it. It’s not easy for adults to learn, so imagine teaching a distractible young child to do it. Here’s a video of a training session with Rob’s son Michael:

Video of a training session for a pediatric body-powered prosthesis

In the video, you can see the adults giving him positive feedback when he does the right thing. This is essential to learning; the quantity, quality, and promptness of feedback directly affect the development of a skill. Rob’s idea is to build a small device that would measure the tension in the cable and make friendly sounds to tell Michael that the gripper is opening and closing. Now, instead of just being in short sessions, the feedback would be instantaneous and constant, hopefully helping him learn faster and better.

Rob had already done some work, but was stuck on a few engineering problems, so we engaged Jack Walker, a design engineer who volunteered his skills to the Open Prosthetics Project. They’re working out the details and keeping us informed. You can follow developments on the pediatric trainer project page. If you want to volunteer or offer suggestions, please contact us and we’ll put you in the loop.

Metal Trautman Hook · 31 March 06 by Jesse Crossen

We sent the Trautman Hook design off to ProMetal and the printed metal parts arrived yesterday. Today, we got finishing tools (screws, drill bits, a tap, and a die) from McMaster-Carr and put the device together. Here are some pictures of the parts when we got them:

Trautman Hook parts made with the ProMetal processTrautman Hook parts made with the ProMetal processCloseup of a Trautman Hook part made with the ProMetal process

As you can see in the closeup, the printed surface is a bit grainy, but not unattractive, and vibratory tumbling would help it look smoother. After a little drilling and threading, it went together without a hitch. Here’s the assembled device:

A Trautman Hook made with the ProMetal processA Trautman Hook made with the ProMetal processA Trautman Hook made with the ProMetal process

The action is smooth and the backlock is tight, the only issue is that the grippers don’t line up perfectly, probably due to the fingers warping a little during heat treatment. The total error is about 0.050 inches.

The next step is to test it with a body-powered harness, then we’ll try to break it to see where it needs to be stronger. Also, we’re already planning on making a few revisions that would make the device more durable. The cost of this prototype was $500 (ProMetal’s minimum order) plus about $50 for finishing tools. Thanks to Kenneth Heide, CPO for funding it.

Rapid Manufacturing · 13 March 06 by Jesse Crossen

We’ve been doing a lot of research into rapid manufacturing (RM) lately. It’s a way of building complex shapes from layers of material, and it will be how many things are made in the future. What’s most interesting about this technology for prosthetics is not the “rapid” part, it’s the fact that you can make things in very small quantities at a reasonable cost. In the prosthetics industry, this means that very small groups of users, like extreme skateboarders missing one foot, can have products made just for them at a reasonable cost. RM also makes it cheap to introduce new products, like we’re doing with the Trautman Hook. Through our consulting business, Tackle Design, we’re also exploring new applications of RM technology to prosthetics in response to a public announcement from the NIH.

Prosthetic Patents · 9 March 06 by Jesse Crossen

Another Tackle Design project, the All Patents Initiative is building tools to make the entire US patent database searchable and accessible. This will help researchers study the history of innovation and give the public access to an important part of their national heritage. The searchable data for patents before 1900 just came in from processing at HP Labs, so we did a simple search for “artificial limb”. It turned up 81 patents from 1852 to 1898, mostly for leg and foot designs. Many of these were probably developed for veterans of the Civil War. The old illustrations are beautiful, and they might contain some ideas that are still useful today. For instance, note the similarities between an 1891 patent (US Patent 450,476) and an image from this 1998 research paper:

US Patent 450,476An endoskeletal finger from a 1998 research paper

We will continue to search old prosthetic patents for “new” ideas. Here are some more great images from the collection:

US Patent 167,779US Patent 197,943US Patent 507,453

More Quotes · 9 March 06 by Jesse Crossen

We’ve sent the Trautman Hook design to more manufacturers for quoting, and the results are good. There are two direct metal processes that are in the right price range, Prometal and SLS Laserform. Both start by binding particles of stainless steel together with plastic, Prometal by spraying on the binder and SLS by melting it with a laser. Then the part is sintered in a furnace, which vaporizes the plastic and fuses the particles of steel together. At this point, the part is still porous, so it is heated again in the furnace next to an ingot of bronze, which melts, flows through the part, and fills all the voids. The resulting part is a composite of stainless steel and bronze. Below are the quotes we received for the two processes:


Rapid Tool Inc. (SLS Laserform ST-100)

Note: The rapid prototyping and manufacturing industry is very dynamic, and these prices may not be accurate within a few months of February 2006.

The best aspect of these processes is that, unlike with plaster casting, the batches can contain multiple designs. For instance, a batch of ten could contain five left-handed hooks and five right handed hooks. We are in the process of getting prototypes made using these technologies.

SBIR grant · 28 February 06 by Jesse Crossen

We are applying for a Small Business Innovation Research (SBIR) grant from the NIH in response to a public announcement that requests research into new ways of manufacturing medical devices. Applying for this grant is going to take up most of our time in the next few weeks, so there will be very little research going on. Hopefully our efforts will pay off later this year, and meanwhile we’ll keep you updated about the status of the application.

Manufacturing Quotes · 27 February 06 by Jesse Crossen

Based on lessons learned from the first prototype of the new “Trautman-style” OPP T-Hook, we modified the CAD files to be more tolerant of process variations. Then we made STL files and sent them to a number of rapid prototyping companies. We requested quotes for quantities of 1, 10, and 100 devices, and it came out as follows:

Quickparts.com (plaster casting process)

Precise Cast (casting with CNC machining):

American Precision Prototyping (investment casting, not including final machining of holes and threads):

Synergeering Group (direct fabrication in Titanium)

Note: The rapid prototyping and manufacturing industry is very dynamic, and these prices may not be accurate within a few months of February 2006.

As you can see, the price for a single design is high because of the fixed costs for setup. Still, it seems like making affordable hooks will be possible with some investment in inventory. We are also looking at alternative materials and processes that might reduce the costs. After all, materials have come a long way in the last 100 years, and there’s no reason to adhere strictly to the existing design.

You can download the CAD model (4.8M zipped) if you want to experiment with the design or STL files (2.8M zipped) if you want to get your own quotes. Warning: This version is largely untested and may not work as intended.

The Trautman Hook · 10 February 06 by Jesse Crossen

We have made a preliminary prototype of the Trautman Hook. After Kenneth Heide, CPO generously lent us two used hooks and two new ones, we reverse engineered them and made a CAD model in Alibre Design. Below is the original hook and a picture of our CAD model:

The original Trautman HookCAD model of the Trautman Hook

We made some small changes to the design based on the areas where the used hooks had been broken and welded back together, and there are probably more opportunities for stengthening and weight reduction. As soon as we had finished the model, we emailed it to Bill Watson at Anvil Prototype & Design, who printed it on his Z Corp rapid prototyping machine and filled it with cyanoacrylate (super glue) for strength. We we able to assemble the parts into a moving model to test the design:

ZCorp prototype of the Trautman HookZCorp prototype of the Trautman HookZCorp prototype of the Trautman Hook

The back lock works perfectly, but the opening action is a little rough at the beginning. This may be due to the high friction between the rapid prototyped surfaces or it may be a geometric issue; we will do more testing to resolve the problem. Our next step is to refine the model and try casting it in metal. Thanks to Anvil Prototype & Design for donating fast, high quality rapid prototyping services.

You can download the CAD model (3.7M zipped) if you want to experiment. Warning: This version is largely untested and may not work as intended.