Personal Project: Creating a Prosthetic Leg

Three Project Ideas:

1. Our first project idea was creating a prosthetic hand. My partner, Elizabeth and I, considered this because this idea of making a prosthetics was really interesting to us, and since we had started working with understanding how the wires in hands were all connected in the hand, it would be a really interesting project to figure out how we would connect the wiring of the hand, and we would also be creating a project that we could give to a program, called enabling the future, that asks us to 3d print and design the prosthetic hand, and it would give the hand to an adult or child in need of the hand, and with this program, we could design the hand to colors or a pattern or character the child or adult wants on their hand. This allows us to have more of a personal connection with the person we are making the project for. This project would be challenging, but there are instructions to help us build each of the pieces. The challenging parts of this project would be how the wiring in the hand will be able to connect to the person receiving the hand and how we will have the person with the hand control the new hand. It will also be a challenge to scale and make sure all the dimensions on the hand line up to fit each other. Different from the source, we can create our own design or pattern to fit a specific person, and can also come up with creative or different ways to allow the person receiving the hand control the hand.

2. Our second project idea was creating a lot of small 3d printed pieces to make tasks like holding a bag or a cup easier for disabled adults and children. We watched a video in engineering class, showing the impact for a disabled adult to be able to hold their cups or hold their bags on a wheelchair, for example, or for a child to receive a new game or toy that they can do, even if they may not have the ability to use their arms or legs. This project allows us to create a multitude of projects, all with different functions, and that can simply be designed and modified on fusion and then can be 3d printed. The difficult part of this project will be coming up with multiple projects, and modifying something as simple as a coat or bag hanger and making it more creative and more advanced, but this can add differentiation from other designers doing a similar project to ours. It will also be challenging to take into account the limited abilities of some of these people who need these 3d printed assistive object, but it will also be a fun and creative project, that will be helping people along the way. We would probably be making this project from scratch, off of our own designs.

3. Our third project idea was to create a prosthetic leg. To make a prosthetic leg, we know would be the greatest challenge out of our three project options because there is no website with instructions, and we would have to make the project from scratch, without much guidance, with a very hard project to do, but it would be fun to be able to make such a large prosthetic that so many people are in need of, and be able to create most of the whole project on just a 3d printer. Even though this project would be challenging to create the leg, foot, and ankle joints, without sketches or resources directly helping us make this project, it is a fun and creative project we could create in order to potentially help someone in a great way.

Final Project Decision:

We decided to make the prosthetic leg for our personal project because it is an exciting challenge, that we have the freedom to design in any creative way we can think of, while also helping someone in need. We liked the idea of building a leg more than a hand because with the leg we could really focus on the calf, ankle, and foot, whereas with the hand you have all the moving parts in the finger, and with kids already making a hand in our class, we wanted to create something challenging, yet something that can help people in need. For our project to be successful, we have to make a calf, hopefully looking similar to the shape of a leg, ankle joints that provide mobility to the foot and connect the foot to the leg like an ankle would, and would have the leg fit into the foot, with all proportions relativity normal to the foot and leg size similar to a child, because our 3d printers can only print objects so large. We will be trying to use as many resources as we can find to help us with our project, but as we've been researching for this project, there is not straight instructions, downloads, sketches, or guidance really to this project, so it will end up being the creative design Elizabeth and I choose to create, not a specific resource. We saw a picture online of a leg with many holes that was 3d printed, and even though it does not come with instructions, we can use this image to model off of and create our own version of this picture or at least attempt to, without actually using any files, but purely trying to recreate a design, adding our own pattern and design.

Materials:

3d printer (to print out all the pieces that create our project)

PLA (material used in 3d printers)

Zip ties(to connect whole project together)

Velcro (to connect ankle joints with the leg and foot)

Screws (to find correct sizes for ankle joints)

Drill (to create hole in foot)

(**all helpful Fusion tutorials and websites that were used are listed at the bottom of this page under helpful resources)

Design specifications:

The goal of our project is ultimately to create the calf of a leg, connect it to a foot, and have the foot be able to move by the use of ankle joints, to make it as similar to a prosthetic leg as we can. We do not want to spend anything on this project, because with the type of project we are creating, we will be able to create everything by the use of a 3d printer, and other materials found in our FAB lab. The dimensions of the leg is approximately 19.4 cm long and around 5.71 cm wide. The foot is around 3.28 cm wide and 14.14 cm long. The materials we would use are listed above and include a 3d printer, PLA, zip ties, velcro, screws, and a drill. Our project will have the ability to be used inside and outside, as it will be a leg, and we hope it functions in the same way typical prosthetic legs function. Our project will be portable, as it is small enough to be a leg for a toddler, but it would also travel with whomever wears the leg because it is a prosthetic leg, and will function as a leg, so will go wherever the person who wears the leg goes. Since the project will be made for the majority, entirely out of PLA from the 3d printers, the leg will not connect to the Internet or use Bluetooth because it is just a simple leg, and will function as a normal leg. There is not going to be any project inputs or outputs as well because this project does not involve electronics, but does involve a lot of skill in working fusion and 3d printers to be able to design this project. There is also no website that we are basing this project off of, we are simply using an image we found on the internet and using it to try to recreate the leg shape and pattern of the image we found off the internet. The image had spontaneous lines to create the holes in the leg, but we intend to make a more typical pattern such as with squares, but overall this is completely our design and trying to recreate the general shape of a leg. The tools we need for the project in the FAB lab are the materials listed above, the 3d printer, PLA, zip ties, velcro, screws, and a drill, all of our materials can be found in the FAB lab, and we can use Fusion 360 in the lab as well to create these 3d objects.

Initial Plan and Making the Prototype:

When we started this project, we believed that we could figure out a way to look for a website where we could use a detailed 3d leg and we could scan the leg, in order to be able to easily create the shape of a leg on fusion, that we could manipulate to make different parts of the leg and parts we could add patterns to. It was not that simple. When we looked and found a website that had a 3d scan of a leg, we downloaded it Fusion, and it was able to download, but fusion would not recognize the object as a sketch, so I could not trace the leg or manipulate the leg at all, so this would not work to create a project off of. Then, We decided to do some more research to try to find any websites with tutorials or files to create a 3d printed leg, and there was one website (https://www.thingiverse.com/thing:1574336/makes) that had files of a calf and foot and part to attach to the leg, and after looking at the different patterns, this was similar to the design we saw in the picture and wanted to model our leg after. We used these downloads, but these downloads were not recognized as sketches by Fusion, either, so I could not see the design techniques or how the original sketch was created and curved to make that design, but we didn’t want to just use these, we wanted to actually make the project, so we decided to use the foot file and the leg file on this website, and we 3d printed them in very small scale (21%) so we could use this as a 3d model to judge how we should make the leg and what curves and shape it need to fit with the foot, and I would also use this prototype as a judge for scaling and making sizes proportionate to the sizes of the prototype leg. We we also use this foot as the foot file for our project because the main focus of our project is the leg and ankle joints. My initial plan went from scanning or tracing a design, to creating it, making the leg, while Elizabeth makes the ankle joints, then print the foot and put the object all together.

Workflow- (actual plan: decisions and building process):

I tried to create my first design just to get an understanding of the shape of a leg, how hard it was going to be to replicate. I began by creating some simple lines and splines to create a simple leg shape, which turned out nothing like a leg looks, but this was a good way for me to see what curves legs actually have compared to the cylinder-like shape I created after I extruded my sketch and made a hole in the sketch to make the “leg” hollow. I saved this design as leg 1, so I could go back to it as necessary, but more likely see the progression of my design in the sophistication of the sketches I created. It was hard to try to figure out how to make the curve go out in one area and become thinner in another. I made a sketch for my leg, using the prototype I created, drawing a diagram to determine just how to draw a leg, where it curved, for how long did it curve, and what the dimensions were, so I could make my leg proportionate. After creating this drawing to refer to, I began making leg design 2. I used the spline fit tool to make the lines of the leg look as similarly to my drawing of the prototype as possible. By creating a new spline for each curve, I was able to manipulate the curves and make sure they were as wide and as low or high as I wanted them. I watched several videos (under helpful resources at the bottom of my portfolio) that were Fusion tutorials throughout this project to try to teach me how to curve an object, while potentially making a hole in the object at the same time, this would be one of my bigger challenges during the project. I tried to extrude splines, like the videos showed me, but this function was not available, so I would have to approach making the hole a different way. I watched videos such as curvature tools videos, how to bend objects like bending a fork on fusion, spline videos and more. I then decided that I could create a hole by making more splines and a sketch similar to the sketch I had already created, so I made more splines on the inner of the splines I had created, they were the same curves and same locations, the inner sketch was just slightly smaller, so I would be able to cut through the outer sketch using the inner sketch. I extruded this inner part, just the inner part, to see how much of a leg it would look like, and I created fillets that went to between 3mm and 5mm, depending on the location and the maximum fillet value it let me do, and this made one big curved object from the inner sketch I had created. I could potentially work off of this design, but couldn’t figure out how to make the hole, so I decided to copy and paste this inner and outer sketches I created and made another leg design, leg design 3. I tried to extrude just the outer ring between the two sketches, but this just made a loop, no sides where the leg needed them. I decided not to extrude the space between the sketches, but the outer sketch extrude to 30mm, and I could then extend my sketch of the inner sketch to make the hole go all the way through the outer object, to make a hole all the way through the leg. Originally, I just extruded the inner sketch, but could not see the hole because it wasn’t long enough. Also, I used the combine tool to subtract the inner sketch from outer to make the hole. Then I added fillets to make the leg as rounded as possible, but the limits for the fillets on this object was 1mm to 3mm depending on the section of the leg or side of the leg. I then watched a mirroring video to try to mirror to make the final side of the leg, because when I extrude the leg, it got rid of one of the sides to complete the leg. I first tried to make this new side by using the same sketch and extruding it 2mm in the opposite direction that I extruded before, so it could have it be the same shape on the other side of the leg and match up because it is the same sketch, and I had to undo the fillets to make this work, and the restriction for the fillets after I press pulled another side 4mm and added 1mm to another side, I could only have fillets 1mm to 2mm depending on where it was on the top vs the bottom, and I made 3mm fillets for the sides. This made the leg look very boxy rather than round because the limits for the fillets were so low. To make it more rounded, I looked at chamfer, sculpture, and forum videos. After watching these videos, I decided to use my second design, because it was the most round to start, and I could extrude the inner piece 30mm to combine and subtract from the outer sketch and object. Since the fillets were already made, it was hard to create another side, so I extruded one side 2mm wider to have more room to create new fillets and work with later, and I tried to make a new side to lie on top or on the other side of the leg, but it would not line up right. I decided to mirror the leg, so I made the object a component, because it wouldn’t let me mirror the object without it being a component, and I made a plane because it wouldn’t let me mirror the object unless I created a plane, and I created a plane with an offset at 18.2mm, halfway through my leg, so I could create one large object by mirroring whole half of object. I used the inspect tool to find the dimensions of the leg. I then printed out a mini prototype of my leg, and I realized it was too wide, so I changed my mirror plane so the sides that were being mirrored were not as long, so I could attempt to make the object more rounder. I then began creating the pattern on my leg, and despite the pattern tool not working to create squares for my leg, I created 8 by 5 rectangles, using the combine tool and extruding them around 100mm, so the rectangles would create holes on both sides of the leg, and on the side, my rectangles were different sizes, so they did not collide or combine with the holes made in the front or back of the leg. I then exported the file of my leg, the top and bottom half were exported separately, as stls so I could use the 3d printer to print them, at 250% of its typical build. I then printed the foot at around 31%, making it smaller than the leg. We then connected the two pieces of the leg by zip ties, that were black, so they blended in a little better, and we used velcro on the ankle joints and the sides of the leg and foot to be able to put the ankle joints on the leg, and we ended up having to drill a hole in the foot to be able to use zip ties to connect the back and front of the leg to the foot, so it would be more stable and try to hold it together. This was our project, and we will continue to make improvements to make our leg stand more stable and have more fluidity between joints and the leg and foot.

** All pictures of my project are at bottom of my portfolio

**All files are in folder at the bottom of my portfolio

Setbacks:

During this whole process, there was many setbacks in creating my project. The first setbacks came with my initial plan to create the project. It was very difficult to find any resources to help me create this project, so most of my project was me guessing and checking different methods to make the curvature right and proportionate to that of a leg. In the beginning, I quickly was setback when I learned that I could not just scan a 3d leg or find files to download and trace or look at the sketches that were used to create the design. There were simply no resources that would allow me to do this, so I would have to create my shape of the leg all to myself. One of the other major setbacks or challenges that I faced was trying to free hand draw, using the spline tool in Fusion, the shape of a leg, this was very challenging and took awhile just to get relatively right, and I watched several Fusion videos, trying to better understand how I could possibly create a more curved, yet extruded object. Another challenge or setback was creating the hole in the leg. When I tried in multiple different versions of the leg, the hole was causing many problems, such as the hole would only go through the center and not all the way through the leg, or would go through an entire side of the leg, causing me to create new sketches to extend the cut through the leg, or also create new sides. I ultimately created a new side by creating the object as a component and creating a plane and mirroring my object on the plane to complete the object, but after much trial and error, trying to create a side to match up with the rest of my object. I also had setbacks with the fillets, as I tried to make my object rounder and rounder to be more like a leg, the fillet tool put limits on the amount of curve I could have, but this ultimately did not effect my project much, as I adjusted to the maximum fillet setting it would allow, which was around 3mm. Another setback I experienced was when creating the pattern on my leg, I tried to use the pattern tool, but the squares kept disappearing, so I had to create each of the squares individually to make the pattern. I also had a setback when putting the leg together, the leg could not stay in place on the foot with the addition of the ankle joints, so we decided to use zip ties and drill a hole in the bottom of the foot, and use the zip ties to create more balanced or stable foot, without it leaning completely, this also gave slightly less, a little more realistic mobility for a leg and foot. There were also several setbacks using the 3d printers, where the prints failed, but these were easily solved issues, just had to reprint the object, it just was a setback, took time out of other potential parts of the project.

Final summary:

What I learned about this project is that it is extremely difficult to do a project by guess and check, trying and experimenting with little to no guidance except a picture to try to replicate. I learned a lot of new fusion skills and better enhanced the skills I already learned, such as the fillet tool, the combine tool, exporting the file as an stil, and I learned better how to use the spline tool and improved on making my free hand drawings. I also learned that the shape of a leg and drawing curves of fusion is a lot more complex and hard to do when trying to create hollow space or a hole, and not many tutorials are helpful with this topic, but most tutorials did guide me in enhancing my Fusion knowledge to build this project.

In completing a large project, I found the importance, when working with a partner, to divide the work evenly and make sure you space your time to account for all errors and setbacks, because in large projects like this, there will be a lot of setbacks and it is more efficient for a partner and you to be working on different parts of the project, so you can get project done in time to account for setbacks. Also, it is very helpful to have some guidance, a tutorial or a sketch to look at or a base project to work off of, especially when you are still developing skills with fusion, like I am, but it also helps you become more familiar with different tools in fusion. Even though my original plan did not work out, like most of the time they don’t, I think it is important, like I did, to adapt to new situations and setbacks and materials and programs that can help you in the long run, adapting can help you finish your project and finish it as effectively as possible because it rarely ever follows typical plan.

If I were to continue working on this project, I would work to make the all around project more stable and supportive. I would increase the size of the foot to be more proportionate to the leg, and make the dimensions of the bottom of the leg fit into the hole or get closer to fitting into the hole of the foot, so the leg and foot could stay together and move without the need for zip ties to hold them together. I would also find a different way to attach or make the ankle joints, because using the 3d printers and the small leg and small foot, the ankle joints are very square and with the zip ties the mobility is either very high or very low, so we need to work on making that a medium and also a stable fit, so works more accurately like relationship of ankle to foot and leg. Overall, I think Elizabeth and I created a very good first model of the leg, learning how hard it is to make a prosthetic leg, and seeing improvements we could make on the model when we continue to work on this project.

Link to Elizabeth’s Portfolio:

While I was creating the leg portion of our project, Elizabeth was creating the ankle joint portion of our project, which she describes the process and steps of in her digital portfolio at this link:

https://sites.google.com/u/0/s/18Hdy_bRIeOHLzT5aehK5ojWAc2YWvdyG/p/1iaUrSMZWPmwK7F0UWBkMeFQORsFpRZ6n/preview

Useful websites:

https://www.thingiverse.com/thing:1574336/makes

https://m.youtube.com/watch?reload=9&v=7AXmZEQwUvY

https://www.autodesk.com/products/fusion-360/blog/sketch-control-point-splines-faq/

https://m.youtube.com/watch?v=l9ymJsPwrU8

https://m.youtube.com/watch?v=ulWdXl4X3oo

https://m.youtube.com/watch?v=IM_sxhp0jzk

https://m.youtube.com/watch?v=kJ-IlkN7kZw

https://m.youtube.com/watch?v=NypRE2aFhh4

https://m.youtube.com/watch?reload=9&v=T1a9iEDWdzY

prosthetic leg google search

Project Pictures:

Project Files: