Wearable Articulated Finger Extension

Assembly Demonstration

Maker’s Note

I’m a hobby modeler, and I like entering MakerWorld contests with designs that push me a little beyond my limits. This is my biggest project so far, and it took many weekends of modeling, printing, testing, breaking parts, and going back to the drawing board. (I have an ever increasing pile of failed prototypes)

My long-term goal is to create a free, easy-to-print and easy-to-assemble parametric generator that lets anyone generate a set of toy fingers fitted to their own hand.

I do have a slight tendency toward maximalism, so I’m not ready to publish the fully customizable version until I’ve confirmed that it works reliably across a wide range of finger sizes, but in the meantime, I wanted to see how people react to the idea and whether it is worth putting the extra work into the generator.

Please try the current version with an open mind, and feel free to leave constructive feedback. I’ll do my best to incorporate the feedback into the customizable version.

Background

I first came across this type of finger extension in this Adam Savage video. It immediately looked like something that would be incredibly fun to build and wear… Then I looked at the price tag :D (after spending so much time on this, I fully understand the pricing. Gary's fingers are truly a work of art both aesthetically and mechanically)

That sent me down the rabbit hole of researching how I could make my own. While looking through existing projects and mechanisms, I found the work of Dragonator, whose notes were invaluable during the development process.

A big shoutout to him. Seeing his amazing model, I’m sure he is one of the few who understand both the pain of designing a mechanism like this and the joy of finally putting it on for the first time and feeling the fingers move with your hand.

Design Considerations

I’ll demonstrate the main design decisions with pictures below, but these were the areas I focused on most:

Cylindrical, adaptive geometry

The mechanism is built around mostly cylindrical finger sections. This makes a final design I find aesthetic. I believe most similar finger have an adaptable base section that goes around the fingers, and the rest of the mechanism is interchangeable. I wanted the whole finger to be driven by parameters.

Low-profile control shaft movement

One thing I struggled a lot with is how to keep the controller shaft as low to the body as possible both at the two end states, and during the movement.

With a few tradeoffs, I think I well achieved both.

Easy assembly

This was the thing I feared the most. In the commercial version, there is obviously no assembly required, it is put together beautifully with additional hardware. I tried different ways of connecting parts, and after multiple failures came up with a snap-in design, which I'm truly proud of.

Clean seam lines

I wanted the finger to have a clean, cylindrical look when it's straight. However cylinders generally have problems with seam lines. I intentionally placed a straight groove at the bottom of the parts, so you wont need to paint seam lines yourself, you can just hit print and know the lines will look acceptable.

The support tradeoff

This is the price I decided to pay. Many things in my design are supported, and while many I could have eliminated, I decided the one-time price of removing the supports is well covered by the gains I got in aesthetics and assembly.

How the Mechanism Works

The finger sections are linked together so that movement from your real finger is transferred through the control shafts to the extended segments.

The animation below shows the movement more clearly than I could explain it in text.