Finger splint???

When we break a bone, typically we get a cast; they are big and bulky, they make your skin itch and smell bad, and they are wicked gross.

However, with fingers, a cast is impractical for many reasons:

• Fingers are small

• Casts are big

• We might need to wash our hands

In recent years, as 3D printers have become more common place, many people have made their own casts as opposed to having the hospital make their own. You need to consult your doctor before you replace a cast with a 3D cast.

Lab:

Over the next two weeks you will be designing and printing a finger split for your hand. Luckily, I found a really smart lady who had done all the work for me, so we will be following her model. :)

Custom 3D Printed Finger Splint

Right before the Christmas break last year, I fell during a local snowboarding competition. Slopestyle under pressure has never been my forte, so as you can see from the video, I fell while making a 180 on a tiny jump. At first, I thought that I just really badly bruised my finger... so it took me a month to finally get an appointment with a doctor that revealed that I had a broken distal phalange of my ring finger. Luckily, all my ligaments and tendons were intact, so the doctor recommended against surgery and reassured me that immobilizing the joint for 6-8 weeks should be enough for it to heal.

Apparently, my fingers are small and short, so after trying on few different finger splints at the doctor's office and at the stores, I've been provided with a sponge-covered piece of metal and tape to fixate it on my finger. At first, I had no problems with this solution, it seemed simple and cheap enough. But over time, I started hating it for the following reasons:

• I had to change the tape every time I washed my hands

• Even after changing the tape, it would take a few hours for the splint to fully dry

• My skin was irritated by tape and constant moisture

• It was impossible to type wearing that splint

• The splint was objectively ugly

So, I decided to come up with a better solution to my problem and make my finger's recovery a much more pleasant experience!

Step 1: Measure Your Finger

For this step you will need:

1. Any 3D CAD software (I used Autodesk Fusion 360 - it is free for university students)

2. Your measurements from Step 1

This tutorial assumes that you know how to use CAD, but if not, there are many other resources that can teach you how to use it.

We start by creating 4 planes with the following coordinates:

1. z=0 (base)

2. z=B/2 (our joint)

3. z = (A+B)/2 (middle of the distal phalange)

4. z = B/2 + A (tip of the finger)

Then, on each plate, create an oval of the following measurements (note x is length, y is width) :

1. x = E1 y = E2

2. x = D1 y = D2

3. x = C1 y = C2

4. x = C1 y = C2 (this one doesn't matter too much because we will be exposing half of it later

For each of the ovals, create a larger oval around it to make an oval hoop with a wall thickness of .1"

Now, use the Extrusion tool to connect all the oval hoops into one shape. We now have a basic shape of a finger splint!

However, now we need to satisfy our breathability and ability to type with the splint. To do that we have to make some few holes for ventilation and expose the top part of the pad of the finger up until plane #3 (don't go below it, it might destabilize the joint). Also, keep in mind that if you are using an FDM printer, you might need to print with support which will need to be safely removed. The last piece of advice is that the fewer holes there are, the more sturdy the splint will be, but the more holes there are, the more breathable it is.