Introduction: 3D Printing Health: Custom DIY Orthotics
*Update:* We are thrilled to announce that our project and story has recently been featured by several DIY websites across the web. Thanks for your support and helping share our project!
- 3DPrint.com: "With self-sustainability available at the 3D printer, designers like Matter921 are showing us exactly how you can handle foot care on your own and with very little expense."
- 3Ders.org:"Matter921 has created an easy to follow 3D printed custom orthotics tutorial that could have your feet humming in no time."
This Instructable will show you how to make your own set of custom orthotics. Orthotics are supports for the arch of the foot that go inside shoes, helping relieve pain and improve quality of life. Virtually everyone can benefit from having them. Problem is they generally cost upwards of $500... simply too much for many individuals on a tight budget. An unsupported arch can lead to knee pain, bunions, and lower back pain, but can also cause serious conditions like plantar fasciitis, hallux rigidus, morton's neuroma, metatarsalgia (nothing that feels good).
Me and my accomplice (Nate) are makers, scientists, and engineers. I am an undergraduate physics major and engineer in training (fortunate to have access to my university's 3d printer to facilitate my DIY hobbies). Nate is double majoring in physics and chemistry; he's headed to graduate school for biomedical engineering. We set out to engineer the first DIY method for 3D printing custom orthotics. 3D printing offers a cheap and effective way to innovate. We put in hours of research and prototypes into making the best custom DIY orthotics available.
- Easy: No experience? No problem!
- Effective: Durable and precise.
- Quick Build: Roughly 3-4 hours.
- Inexpensive: Less than $5!!!
So here it is... Ask questions if needed in the comments; we'll try to answer right away!
Step 1: What You Will Need:
Just a couple things needed for the project!
- Soft imprint clay.
- Flour and salt
- Cooking oil
- Cream of tartar
- Food coloring
- Smartphone, tablet, or camera.
- Access to a 3D printer*
*If you don't personally own a 3d printer, be sure to look for a 3d Hubs location nearby. Some schools, universities, and libraries also provide 3d printing services.
(Or with all the money you save making these orthotics, buy your own 3D printer!)
Free Software: This is what we recommend.
- 123d Catch: This app can be found in both the Android and Apple app store. It turns your camera into a 3d scanner, allowing you to capture models that you can print. In this project, it'll be used to scan impression molds of the feet in order to create a digital model of the necessary arch supports
- Meshmixer: This program allows for easy editing of the .STL files produced by 123d Catch. This software is the real workhorse of this project
- netfabb Basic: This software does an extremely good job of repairing fragmented .STL files, and will come in handy at a few points in this project
- 3d slicer compatible with your printer: A must have for any 3d printing project. Slicers take digital models and convert them to instructions that 3d printers can follow to produce the desired part. Make sure the slicer you use is compatible with the printer you intend to use! I'm printing on a CubePro Duo, so I'll be using a 3d Systems produced CubePro software. Other free 3d slicer options include Slic3er and Cura
That's it! Now, lets get started! First, we have to make or obtain clay that will be used to make a mold of the underside of the foot. By doing a 3d scan of the mold, we'll digitize the model, and send it through a few software tools to allow for 3d printing! It's a super fun process!
Step 2: Preparing Soft Clay for Casting
The first necessary step is to get some clay that we can use to create a mold of the foot. If you have Play-Doh or soft clay it would likely work for this step. We wanted to be responsible for all aspects of this project from start to finish, so we decided to make our own clay for foot molding. The following are the instructions for the play-dough we used:
- Mix flour, salt and cream of tartar in a medium-sized pot
- Add oil and colored water and stir until ingredients are well blended.
- Place pot on the stove over low/medium heat.
- Cook the soft clay – stirring often – until begins to pull away from the sides of the pot (about 3-5 minutes)
- Allow it to cool a little and then knead for a minute or so.
- Store in an airtight container
Alternatively you can find some great detailed instructions for making play-dough without cream of tartar using this instructables link by KatieStiles.
Step 3: Foot Casting:
It might seem nerve racking or difficult to get the proper foot cast... but it doesn't have to be! We have lots of details so you can cast the same way they do it at the podiatrist's office. The positioning process we're demonstrating is called the ICB method.
Key Reference Points:
In this step we'll find the key reference points required for accurate foot positioning. These reference points include:
a.) The talo-navicular reference points. Bisect these as shown.
b.) The second metatasal head. This is the joint above the second toe.
c.) The tibial crest. There is a clear crest that can be found while feeling your shin.
*all of these points are shown on the first image! Mark each spot as shown. Draw a line down the tibial crest to the interseaction of the talo-navicular points. Draw a line up from the second metatarsal to this bisection point as well.
Making the imprint:
- Get a feel for properly aligning and imprinting the foot. Its important part of this project!
- Proper casting is done by aligning the reference points to make a straight line as viewed from the front.
- It is good to have a partner help when making the impression. The partner will be the one guiding the foot throughout the process.
- When performing the right foot imprint you can support yourself on the left side. Place a large/even amount of clay directly below your right foot. The partner should hold onto your ankle. Have the partner slowly depress the heel to the bottom of the clay. Then depress the clay below the fifth metatarsal (small toe base joint). Depress the clay below the fourth, third, second, and finally first metatarsal. At this point the heal and the toe joints should be depressed to the bottom of the clay. Remove the foot vertically out of the clay.
- Analyze the cast. If properly performed the arch should be clearly evident and should match the arch of the foot when in the proper alignment. Practice makes perfect! Keep trying until its comfortable. Pictures 2 through 6 of this step are a few images of us doing the imprint process. Feel free to refer to them as a guide!
- To make the 3D modeling easier, remove the excess clay from around the mold. Take a regular shoe insert and outline the first half of the insert on the clay. Use a butter knife to cut straight down from all points from this sketch. Be careful not to alter the foot cast while performing this step.
Step 4: Foot Casting: Movie Tutorial
To further clarify the casting procedure we made this short video... get out the popcorn!
Step 5: From Playdough to Computer Model
The next task is to digitize the play-dough imprint that you have created! This will be done using a very impressive 3D construction program available through Autodesk 123D Catch.
Creating the 123D Catch file:
- First thing is to install the 123D catch program on your phone or tablet. There is additionally an option to take photos with a camera and then load them in online.
- When performing the 123D Catch, the program will walk you through very clearly how to take the pictures and what angles to shoot from.
- Because of the importance of shape when making this computer model, make sure to take a lot of photos from all angles. We took roughly seventy photos of the orthotics for this project to insure proper shaping!
- Several things were noted specifically when creating our project. Firstly, the background behind the orthotic should be highly patterned with many different shapes/designs. We found a map or colorful newspaper to work well for this step. These designs help the reconstruction program locate the positioning of each photo in the series. Additionally be careful not to have shiny surfaces in the images and be careful not to let the orthotics or surroundings move while taking the photos.
Step 6: Importing Model Into Meshmixer
Once your photos have been processed and converted into a model with the 123d Catch app, you can begin prepping your orthotics in Meshmixer. There are few things you'll want to do in this program, including leveling the model, adding a base, and scaling it to the correct size.
But before that can be done, the model must be imported into Meshmixer! If you don't have Meshmixer, it can be downloaded here: http://www.meshmixer.com/download.html
The model will be uploaded to Meshmixer as a .STL file. To download a .STL file from the 123d app, navigate to the model homepage, and click the large blue button that says "Edit / Download"
In the submenu that appears, select "Download 3D Models" (Image 1). This will trigger a screen to appear with three different files to select and download. The only one we'll be need is the .STL file, so the other two can be deselected. Then, simply click "Download Models" and wait for your file to become available! (Image 2).
When you open Meshmixer, the welcome screen should have a sidebar with various options. In the middle are a few more buttons you may select. Choose the import button either on the sidebar or near the screen center (Image 3). This will initiate the process of loading in your file. When the import is complete, a 3d model of your feet imprints should be visible (Image 4). Don't worry if the model is inverted, off-axis, or scaled incorrectly- we'll cover that all in the next step!
Step 7: Orienting the Model in Meshmixer
When the model gets imported into Meshmixer, it can be upside-down, on its side, or anywhere in between. It is of vital importance the get the model upright and level in order to get it to print correctly. The bottom of the model is red in the Meshmixer program, and the top is white, so we must flip the model until this white side is seen. The model can be re-positioned by clicking the edit button in the sidebar and selecting transform from the menu that pops up (Image 1).
Once the transform button has been selected, a 3-axis pivot point will form in the center of the model. If the arrows are dragged, the model gets translated, and if the arcs between the arrows are pulled, the orientation changes. Since we want to flip the model, choose an arc corresponding to the arrow that is vertical, and flip the model over until the top is level with the ground-lines (Image 2).
Next, the model must be oriented so it runs along these ground-lines. Rotate the model using the arc that is parallel with the ground. Once these transformations have been completed, the model should look similar to the one in Image 3. If that's how yours looks, you're ready to move to the next step- scaling the orthotics to size!
Step 8: Scaling Orthotics in Meshmixer
Obviously, we want these orthotics to fit our feet, but the dimensions oftentimes get mixed up going from 123d Catch to Meshmixer. In order to get around this problem we included the ruler in the model for scale. We'll make use of that now!
On the side-menu, press Select, and use either the brush or the lasso tool to remove all of the material that extends beyond the extent of the ruler. Once this is done, your model should look like Image 1.
Next, return to the transform menu by navigating through the edit options on the sidebar. Near the top of this menu, use the drop-down button to switch from the local frame to the world frame. Because we oriented the model along the ground-lines, the length of the model exactly corresponds to the z-axis. Since the length of model is now the length of the ruler, scale the model so the z-axis length is the correct size. For a 12 inch ruler, the z-axis length should be set to 304mm (the equivalent of 12 inches). This will adjust all of the other dimensions to the proper scale (Image 2).
With the model properly sized, the material around the orthotics can be selected and removed, leaving just the digital copy of the foot imprints we created (Image 3).
Step 9: Filling Print With Netfabb
As you may have noticed from looking at the file on Meshmixer, the model in its current state only represents a surface- it is not solid volume. We'll resolve this problem on netfabb, a program designed for repairing .STL files.
Export the model from Meshmixer as a binary .STL file, and open the file in netfabb. When the file is opened, it will look something like Image 1. Notice that there is a large exclamation mark. This makes it pretty clear that something is not exactly right with the model. By rotating with a right-click, you can see that there aren't any bottoms to the orthotics!
To solidify the model, press the red plus button along the menu at the top of the screen. Next, press the button that says "Automatic Repair" near the button of the window. In the menu that pops up, execute a default repair (Image 2). The repair may take awhile, but once it is complete, select "Apply Repair" on the lower right-hand side of the screen, and choose to remove the old part (Image 3).
Now, the fixed part can be exported as an .STL for use with your 3d printer slicer. You're almost done!
Step 10: Preparing for 3d Printing
After a good bit of experimentation with the print parameters, we came up with a combination of settings that works incredibly well for what we're trying to do.
The strength, flexibility, and weight makes ABS a perfect material for these orthotics, but I'm sure they would work well in PLA or with certain specialty filaments.
Upload the .STL file from netfabb into your slicer of choice. I am used the CubePro software that is limited to use with the CubePro Duo I used, but the settings should be very similar on your slicer.
The following print settings were what I found worked best. Try to match them with the available settings on your slicer:
- Layer Height: 300mm
- Fill Spacing: 20mm
- Outer Walls: 2
- Bottom Surface layers: 2
- Top Surface layers: 14
Layer Height isn't super important for a print like this, so I did the maximum my printer would allow. This makes it go quick, and ensures that the top surface is very thick. Make sure to not use more than the recommended outer walls and bottom surface layers, and keep the fill spacing high. All of this material gets removed in the next step, and basically is just functioning as support during the printing process. Finally, ensure you keep the number of top surface layers high: the orthotics are constantly getting walked on day after day, and we want to make sure they don't flex or break!
Image 1 shows the full settings I used to set up one of the prints, and Image 2 is a picture of the orthotics model after having gone through the slicer.
Step 11: 3D Printing Time!
We've finally reached the point where we can print the orthotics!
My print for these blue orthotics took about 4 hours and used around 75 grams of material. Included are a few pics of the process, and of the completed orthotics as well!
Go for it! Almost there!
Step 12: Finalizing Your Orthotics
Up to this point you've created a model for your orthotics, scanned it and turned it into a printable file, and printed it! Now, all we have to do is finish that print into something you can actually use.
Due to the settings we chose for the 3d printer, there are a few unique features to these orthotic prints. First, you'll notice that there is a hard and thick top surface. This is due to the large number of top surface layers we specified. Next, the bottom surface is really thin and fragile. Again, this is because we only chose to have 2 bottom layers. Finally, due to the low infill, there is very little material between the bottom and top layers. The reason for such a little amount of material on the bottom and interior is that all of this will get removed anyway! So, lets get started with that!
Using a pliers, poke through the bottom surface of the print. This should be somewhat easy to do since it is only 2 layers thick. Now that a hole has been created through these layers, use the pliers to grasp onto the bottom surface and begin pulling it away. Note that around the heel, where the model was very thin, there will be little to no material to pull away before the hard top surface begins.
Once all the bottom material has been removed, start pulling off the sides of the orthotics. This can be done with a pliers, or the material can be stripped away with an x-acto knife. In addition, remove the infill material from the bottom of the orthotic. Once this material is removed, make sure that the heel and toe of the orthotic are level on the ground, and that the thickness of the orthotics are about a constant 3mm thick. Due to artifacts of the printing process, you may need to clean up the orthotic now to smoothen the bottom and shape the orthotic structure.
Once you've done all of this, your orthotics are complete and you're ready to jump up and start running back to work!
Step 13: Final Thoughts
As a bit of a disclaimer, we want to make clear that we're not trying to replace doctors or podiatrists by putting this project together. Nothing can compete with their expertise or abilities, and if you have the means to utilize their services, go for it!
That being said, from our experiences these 3d printed orthotics function at the very least as a suitable replacement for those not willing or able to invest in pricey prescription orthotics. The fit of these orthotics astounded us, and really helped relieve tension and pain for those we printed them for. It was so much fun to come up with this idea and figuring out the best way of doing it. We're excited to hear about where you go with these ideas- please leave a comment letting us know if you tried to make a set, or if you have any questions. I really hope you enjoyed this project- we sure did!