This is my original design based on my modular hand, skinned and articulated for Jack Skellington from A NIghtmare Before Christmas. I consider it a puppet hand but it could be adapted for animatronic control. The actuator is designed to be held and manipulated under an extended sleeve. Unlike an attached gauntlet, it can disengaged easily. As well as looking cool, it is designed to be very easy to print, employing 12 printed-in hinges, 4 of my custom captured Super-pulleys in the palm, and channels for all of the thread and elastic string. This kind of wire/spring control can yield very subtle, beautiful performances.
Follow and watch this space for assembly videos, updates, new skins to come! Zombie, skeleton, alien hand, perhaps Iron Man or Edward Scissorhands, who can say?
A little bit of hardware required:
25lb fishing line (preferably braided and doubled)
2 - 1/2"-3/4" long socket 1/4-20 bolts to attach hand to gauntlet
3 M4 or #8/32 screws or knobs for adjusting finger string tension ~3/4" long
3 nuts (M4 or 8/32)
2 small screws/washers to lock down the stretchy string inside the palm (these can be harvested from old filament spools)
optional - a 12mm neodymium magnet at the wrist to keep your sleeve in place
Happy Halloween Everyone!
Also, a shout out to my favorite Youtuber, James Bruton. If you are a fan of mechanized cosplay, check out his channel XRobots. I could not have accomplished this without the many enjoyable hours of watching his incredible process. Please keep making stuff, James!
Tolerances may vary. Please direct message me if you are have trouble in either direction (too weak or too stiff.) I would love to do a customizer for a robot hand using these techniques, and I appreciate feedback. A tolerance dial would be a great feature for designing print-in type mechanics.
I carefully designed this from scratch to be as easy to print as possible. I find using a .25 nozzle gives me great results with the fine details here. The pulleys are designed to be nudged with pliers and spin in place. A bit of 3in1 oil in the pulleys and joints seems to help significantly. Silicone lubricant may also work well. The only thing I printed support for were the Fingerpull stringlocks, but they may be fine without it.
In order to to consolidate files, anything designated Right can be mirrored on the X axis for the left hand version.
I will post a detailed assembly video soon. The stretchy string is tied into the top phalange and strung through channels in the fingerbones and backer plates. The backer plates set the angle at which the finger will rest, so you can adjust it at each joint by clipping or sanding material off.
They are held in place with 3mm white filament rivets made with a soldering iron. You can also use 1/8" plastic rod. You may need to hand drill to open the pinholes a bit, but no glue is needed - friction will keep them fairly firmly in place.
Feed the stretchy string through the holes in the palm and secure in the upper corners with a small screw and washer. Trim the ends to no more than an inch, or whatever is comfortable. Now run strong thin braided line in a loop knotted at the tip of each finger and fed through the successive channels into the palm with tweezers. Feed them each through to the base and attach the wrist with the 1/4 inch socket bolts. Don't over tighten. The four looped lines should reach to about the base of the handle. Lastly assemble the fingerpulls with M4 or 8/32 knobs or screws.