3D Printed Articulated Finger Extensions
Introduction: 3D Printed Articulated Finger Extensions
Creepy and intricate, I have always loved seeing the articulated finger extensions. Recently I decided that I wanted a set of my own to match a previous project. Not content with what was already out there, I decided to make my own design.
The project shared here is my current prototype. It does not yet meet all my requirements in regards to looks, but it is already fully functional and can be made by anyone interested.
Supplies
Tools:
* A 3D printer
* A craft knife
* A lighter
* A drill
* A 1mm drill
* A 1.75mm or 1.8mm drill
* If a drill is not possible, a piece if iron wire of 1,5-1.8mm will also work. See "Preparing" step
* (Calipers)
materials (optional in parenthesis):
* Filament (preferably 1,75mm)
* Fishing line or thin strong wire
* CA glue
* (Activator for CA glue)
* (Elastic wire or rubber bands)
* (Zipties)
* (Something that straps around your wrist)
Step 1: Why I Made This
Why did I make this? First of all, because I can and they are awesome.
My first encounter with the articulated finger mechanism was when I saw them on Tested (video) where <PERSON> showcased them. As is often the case, I vaguely remember it, and rediscover it later with more passion.
A few weeks ago was when I got that passion. I wanted to make a set. Preferably one that matched the 3D printed scales I already have (link to scales). I started looking around the internet to find existing plans. Why design something that already exists. <PERSON>, the creator of the vingers in the first video only sells the fingers themselves. There were 2 reasonable options.
The first option was on thingiverse. These finger extensions were more closely resembling the model by <PERSON>, using a pulling system on the top of the finger (more in the next step). It is designed to be as compact as possible, and the be reskinned with another file. It is brilliantly compact, seems to work well, and should be a decent print. It was also one I did not try myself, because I found something else first.
The second is a model you have to pay for on Cults3d. It is a design that has the style in the part itself. In my case, robot, but there is also dragon and skeleton. 215
It is a pusher system which is a bit limiting in the movement, and places push bars on the inside of the hand. My finger can only move by 45 degrees for the full movement of the extension. I printed a single finger. While it was somewhat optimized for 3D printing, it was a supported print. It also tended to bind a bit because of how the linkages are placed. The style did not really match with anything I wanted, but that is not a valid complaint. There was no real information on the dimensions, so I had to print a random size and hope. It worked fairly okay, but I would have wanted better measurements to determine what I needed to print.
After printing the single finger I wanted to try designing it myself. I wanted a few things.
1. Make the design easily modifiable so I can alter it to my hands (and anyone else's if I do it right)
2. Make the extension's movement happen in as close as 90 degrees of finger movement as possible.
3. Make the design move smoothly. This basically requires the <PERSON> puller design.
4. Make it supportless. I hate supports on mechanical parts, and felt it would be possible to make a design without supports.
5. Make the design match my scales (not in this Ible)
This Instructable is my first prototype of supportless articulated finger extensions.
Step 2: How It Moves
The basic idea of the finger extensions is that it takes the movement of your finger, and extends it to several more joints. The movement of the first 2 sections (from the right) are used to move the next 2 sections of finger.
On the first joint there is a linkage that is attached to the leftmost section of the finger. This linkage goes into a gear set that inverts the movement so it goes the right way. A linkage is used to convey the movement from the middle of the mechanism to the tip of the mechanism.
I have included images and a gif to hopefully give a good overview of how it works.
Step 3: Design Choices
There are a few design choices that I do want to share with the people making this mechanism. 215