Project 5 (Final) Mixed techniques: Joshua Woody

 

The first step I took in creating this project was determining what I wanted to do. My wife has a chronic illness that affects her joints and it was recommended by her doctor that she wear thumb braces daily. She's gone through a numerous amount of some braces and different styles each one not covering all of the bases that it needs to. There are three joints in the thumb that need to be protected. From wrist to tip of the thumb, the joints are:

·         the Carpometacarpal (CMC) Joint,

·         Metacarpophalangeal (MP) Joint,

·         and Interphalangeal (IP) Joint.

most thumb braces only protect one or two, in addition, the some braces are restrictive to the point where wrist Mobility is impinged. An ideal brace would allow for the most mobility in certain directions but negate hypermobility in the wrong directions and would protect from all four main hyperextension types. those types are:

·         Swan necking, (IP hyperextension)

·         hitchhiker's thumb, (MP Hyperextension)

·         medial over rotation, (MP hyperextension)

·         and CMC instability.

The disease that my wife has creates instability in the joints that would prevent her from doing daily activities. for example, picking up objects dressing and undressing, typing on the keyboard, opening a jar of peanut butter.

Whenever she attempts to do one of these things she tends to hyperextend in one of those four directions: preventing her from accomplishing the task and creating pain in the associated joint. This problem is complex and involves biomechanics, and requires a multimodal approach that would include 3D scanning, Physical clay Sculpting, 3d modelling in fusion 360, 3d printing, and sewing.

Biomechanics is a subject I know absolutely nothing about, so I had to learn a lot in order to start this project. Because I knew nothing about biomechanics the system of rapid prototyping was ideal for this project. In the first step, I took a novel approach of using a 3D scanner. I chose the 3D scanner because I needed my part to be tailored to the human hand, and I have enough of a hard time Drawing a human hand in two dimensions, I could not imagine attempting to create one in three dimensions from scratch in fusion 360. I had seen the 3D scans and prints of the Fist that was sitting out in the shop and saw it as an opportunity to utilize a new tool into the process of making.

The process of actually using the scanner was difficult and required a learning curve. The scanner has its own specialized software that I had never used, and the device itself had large proportions and had to be Tethered to the computer making Logistics interesting for the project. To use the three scanner, I had to identify the best method for creating a 3D scan of a human hand particularly the thumb. For the first 30 minutes I was stuck trying to scan a wheel before I realize that I needed to calibrate this scanner using the software. I then had to figure out the best way to use the dots to create a scannable object that the scanner could pick up. I also had to find a way to stabilize her arm that would prevent movement and secure a clean scan. I end up using a pool noodle that I folded in half and duct tape together. After about three scans the third scan was acceptable and had a pretty high quality to it. however, it was an open mesh that could not be turned into a 3D model without modification. So in order to turn that scan into a 3D model, I needed to utilize the software that I've never used before, the create form software, to planar slice the fingers off of the scan and fix it so that it could be picked up in Fusion 360.

Once I had the model in Fusion 360, I used the hole repair tool and then exported it to Prusa slicer, where I printed the whole hand model to scale on a Prusa Mark 3. I then took the print home, and begin prototyping with polymer clay. I Chose Polymer Clay because it is easy to manipulate while warm, hardens in the refrigerator, and cures in the oven.  The initial clay polymer was used and formed without the 3d hand scan and without wire and it was very fragile. In addition the clay warped while in the oven and I had to start over again. When we started over with the 3D print of the hand, we utilized the refrigerator to cool the part and also identified using the wire where supports would need to go for each of the joints these results turned out much better and helped inform how I would modify the 3D scan and cut away pieces. It was with this prototype that we found the best success in solving the job of protecting all three joints in all four directions.

 

The process of creating a hollow 3D model from a mesh scan was very difficult and it took me probably a few days to figure out. The process I came up with goes as follows: open the mesh in Fusion 360, go over to modify mesh tools, select shell, then select repair, when I selected the shell distance I had to pick a thickness and this thickness value would stay with me and the design for the rest of the design process. I chose 2 mm shell distance thankfully it turned out to be hey solid choice. Once the show had been created The Next Step was to convert it into an object from which you could manipulate it that was the next step once you can convert it into an object I used the create plane and then create sketch and then the extrude tools to cut away different sections of the shelled hand 3D model based upon the polymer clay prototype.

 

 

I then printed the shell on an Ultimaker in my Makerspace, and it came out way too small. I realized that I needed to upscale the design and reprint it. Is it this time that I got my own 3D printer and after setting it up I had an Ender 3 V2 Neo ready to print with PLA Plus, having easy access to this printer at home made rapid prototyping even more rapid and I proceeded to create six prototypes each with small design changes.

The First new print was a simple upscaled version that I used for sizing, it was during this iteration that I identified that I had printed a little bit too large, and also, placement of the strap was going to be a problem, it immobilized her wrist and prevented her from doing daily tasks with that Style. Despite the rest of the brace being too large, the interphalangeal or IP joint was the right size, although too far away from the actual joint that it was trying to support.

 

 

In the next iteration I cut the bottom of the brace off so that the strap would wrap around the hand rather than around the wrist. When this prototype came out I soon realized that the first thumb race giant was too small and once again too far away from the actual joint it was supposed to be supporting however the CMC joint section was ideal. In order to find the correct ratio, I utilized the 3D print of the full hand to Frankenstein the different prototypes together cutting and removing pieces as necessary to get the correct dimensions for the ideal design.

 

 I did this one more time and found the sizing of the IP joint to be off again based off of the shifting of the cuts I had made. I chose to print out two IP joint size sizes for each hand. Doing this enabled me to find the right size for the interphalangeal joint brace for both hands once I had identified that the CMC joint brace portion had been complete and sized correctly.  Once I found the correct size IP joint brace, I then started exploring various materials for the final print. Initially I wanted a resin print because of the non-porous nature that the print style has. The resin printer proved to be too cost prohibited to create medical grade equipment, in addition the print would have fractured fairly easily based off of other resin braces that we had bought to test, such as the oval 8 braces. I then looked into different types of filaments that would be stronger, as well as possibly using the CNC machine if I couldn’t find any strong materials.

I found red PCTG, which is a higher temperature PETG that supposedly had good strength and chemical resistance properties which would be ideal for cleaning this everyday equipment. However I found the red PCTG extremely difficult to work with after testing it on my printer, and modifying the printer to use the higher temperature proved extremely difficult, as I needed to use coding and Visual Studio in order to change the values temperature of the machine’s firmware. Even after upgrading to a bimetal heatsink hot end, and changing the temperature values, the material proved fragile and easy to “spaghettify.”

 

I also looked into Onyx after talking with Ryan, and after testing Onyx, it proved to be the strongest and best solution. After doing one more print with the PLA plus, I identified my final modification, which was to cut the palm down to enable higher mobility in the fingers. With the angle that the palm had been cut at she could not touch her pinky to her thumb, which is something she could do after the modifications were made. After making his final changes I printed the right thumb brace in Onyx, cut the supports out, sanded the material down, and began the process of sewing the strap.

I used a sewing machine and Velcro on a strap.  to create the strap for the brace so that it was adjustable and comfortable. The zebra pattern is symbolic of rare and invisible illnesses. The pattern as a symbol that identifies those with rare diseases based off of the medical adage, “when you hear hooves, think horses not zebras.” Which means, identify illnesses as what they most likely are based off of common symptoms. This adage has been followed by many doctors who use it to simplify and dismiss those with complex or rare diseases, and so wearing the zebra pattern is a symbol against that adage, showing all that zebras are more common than you think.

The result is a beautiful, functional, strong, reliable, unique, stylish, symbolic, and comfortable triple joint thumb brace, which prevents Swan necking, hitchhikers’ thumb, CMC instability, and medial over rotation in the Carpometacarpal, Metacarpophalangeal, and Interphalangeal Joints. Built using a complex multimodal approach, which included biomechanics, rapid prototyping, 3D scanning, clay sculpting, 3D design, 3D printing with complex materials, and sewing. In each section of the explanation above I’ve included prototypes, their failures, and the lessons learned. This also could not have been done without the help of my wife, Clara, and Ryan, who helped inform me on the challenges ahead, as well as provide feedback at each stage.