Hand: open-source Robot Hand
91 comments
·July 17, 2025breakpointalpha
Animats
Feetech is selling actuators which are mechanically R/C type servos, but have a bidirectional computer interface allowing the control computer to find out what's happening at the servo.[1] This isn't new; Dynamixel has been doing it for over a decade. But not at this price point. This Feetech servo is $17, while Dynamixel units start around $70 and go much higher.[2]
The parts list has "need to be strong" for many of the small parts, but they are 3D printed PLA plastic. That's the low end of 3D printing. None of the videos show the hand handling anything.
So this is really the proof of concept model. If there's enough interest, someone could make the parts by injection-molding of something better, such as polycarbonate or glass-filled nylon. The total plastic volume here is so tiny that the plastic cost is negligible, and there's no reason not to use a high-quality engineering plastic.
Nobody seems to do hobbyist injection molding much. TechShop had a desktop injection molding machine, the CNC milling machines to make molds, and even Autodesk Moldflow to design them. But nobody used those tools. A few university maker spaces have similar machines. Because most of the world's plastic stuff is made by injection molding.
[1] https://www.feetechrc.com/
mionhe
Mold design is still difficult when the parts aren't dead simple. The software I've seen is okay with the simple stuff, but once you get even a little more complex you have to understand simultaneously how to design good parts for molding and how to design good molds, both of which are heavily dependent on the type of plastic you're using and the size of the press you have access to. Not to mention how to machine good molds from metal, which is a challenge all on its own due to surface finish and tolerance requirements (and weird geometry that makes the CAM choke...)
In other words, we're not really there yet to bring that activity into the hobby realm. But I hope that we're not too far away.
Animats
They're little linkage parts, mostly flat.[1] Some of those holes are bearings. None of those parts are hard to make, but they need to be strong. They could be made by CNC machining, or in quantity by injection molding, or stamping. But tiny working parts in 3D printed PLA will be too flimsy for that hand to do much work.
Totally fixable problem. Then this hand can go to work.
If this thing catches on, someone might sell an upgrade kit with stronger parts. The designer is already considering a servo upgrade.
[1] https://github.com/pollen-robotics/AmazingHand/blob/main/ass...
stefanka
It’s one of best designs I have seen, I admit. But for that price you cannot get absolute encoders outside the motor, reliable force/torque sensors (think picking up a strawberry), tendons (thread below). It might be too limited for research and real-world projects unfortunately.
jjangkke
Most hand related jobs upwards of $100 per 30 min
If this Robot hand can do those jobs we could see some industries take a hit
0_____0
People have been making end effectors using hobby servos for ages. These servomotors are designed for use in an RC aircraft, they're light, cheap, and expendable.
Industrial needs care not about weight, care less about cost, and care a great deal about capability, repeatability, and reliability.
This is a cool project for a hobbyist but it's not meant to be a serious industrial machine.
Edit: what is with this thread? Lots of very generic positive comments here but not much thinking about what this is actually useful for.
johnmaguire
I think the confusion stems from the fact that you're responding to a joke innuendo thread.
stronglikedan
> Lots of very generic positive comments here but not much thinking about what this is actually useful for.
How can you say that when the person you are responding to is talking about what this is actually useful for?
pwndByDeath
Woosh
ACCount36
...that's how it was in year 2020.
What you're missing is: today, we're nearing the point where actual general purpose robots become viable.
Which means: the purpose of a robot is no longer to sit at a factory line and precisely execute the same exact motions on repeat 24/7. The purpose of the next generation of robots is to learn generalized behaviors, adapt to circumstances, and carry out circumstance-specific actions with active sensor feedback. Which means completely different requirements for effectors.
Which means: repeatability can go get fucked, for one.
MisterTea
> upwards of $100 per 30 min
That is why I'm self employed.
kakapo5672
It took me a a distressingly long time to understand this comment. I'm kind of concerned, and have vowed to get out more.
mrbonner
You haven’t accounted for the 3D printer yet.
echelon
I can't wait for this to be put on a tall roomba base so it can clean my kitchen.
Brajeshwar
Here is what I’m more keen on, rather than the human-like robots that we are all expecting. For instance, I would like a wall-mounted or floor-standing multi-arm robot that serves as a kitchen assistant. One can add or reduce arms as needed/desired. It is custom-equipped with a fire extinguisher, thermometer, and the usual must-haves for a kitchen. It will hold the cutlery, plates, and other items as needed. It will also advise on the likes of, “No, salts usually go in a pinch, would you like me to add in just about 5 grams?”
Thus, similarly for the garage, the DIY table, etc. Just Arms would be good.
bredren
It slices, it dices...
Seriously, though. Vassar Robotics (YC company) has an arm kit available for order now. The original ship date for my order just got pushed back due to an upgrade in the camera spec.
It won't be able to hold knives (I don't think) but there are companies working to bring about your hoped-for wall arm right now.
thrance
Tbh I would rather not have computer-guided knife-flinging arms in my home, be them on wheels or fixed to the wall.
sroussey
I have a parrot (whose beak is sharp enough, thank you very much) that loves to grab a knife out of the knife block and spin around with it.
I have to put a towel over it though today he pulled the towel off and still grabbed the knife and was holding it up when I turned around.
0_____0
Like a mischievous toddler with wings...
seanthemon
It's a well known fact that birds aren't real and you must be a target now.
goopypoop
perhaps sir would prefer… tentacles?
scotty79
I always imagined robot hands hanging and sliding on rails under top kitchen cabinets.
mclau157
Pollen Robotics and HuggingFace are doing a lot for robotics right now!
ge96
Wonder if it will get adopted (huggingface robot) I noticed the eyes/cameras go behind the neck thing for sleep mode
null
TheAceOfHearts
Does anyone know what design considerations, if any, might've gone into deciding to have 4 fingers instead of 5? And what tradeoffs that entails?
I actually saw this posted a few days back on Twitter and had been wondering if there was any deeper consideration for the number of fingers. It seems like you save around $10 in parts by getting rid of a finger, based on the information in the BOM.
p_d_r
It looks like the width of the servos driving each finger makes a certain finger spacing necessary, and I bet five made for an awkwardly wide hand.
FBISurveillance
Great stuff. So 2x$135 and I'll finally get my t-shirts folded for me in the laundry room.
binsquare
The world is designed with humans in mind, it's great to see robotics evolve in this direction to take advantage of that!
baq
Literally the reason for all publicly traded robotics companies going up recently.
poly2it
Why was this downvoted?
agumonkey
Anybody knows of similar projects for exoskeleton or support devices?
SequoiaHope
Beautiful design and I love that it’s in onshape with an aliexpress BOM. I might build this!
ortusdux
I wonder if I have time to make one of these and then decorate it to look like Thing for Halloween!
glitchc
This is great, but to make a comparable hand, we also need very sensitive sensors, at minimum pressure and temperature, across the entire surface area.
falcor84
Absolutely, though I'd be ok with just pressure as a starter.
amelius
Would it be possible to have tendons running through the arms, so the weight of the hand is reduced?
atrus
Will Cogley has had a few different designs with tendoned hands.
https://www.youtube.com/@WillCogley
https://willcogley.notion.site/
So, there are designs out there for that too!
stefanka
Most tendons materials are elastic. That lead to create calibration problems and require proprioceptive sensors in the hand
Symmetry
In practice force sensing is more useful than proprioception in most cases, at least for grasping. Generally you won't the dimensions of an object you're attempting to grasp anywhere near as well as you would know the shape of the hand you're using so a certain amount of underactuated compliance makes the job a lot easier.
stefanka
I agree. But even then elasticity had to be taken into account (and maybe even gravity), if the object is very delicate.
fusslo
Huh, never thought of that
I wonder if companies are experimenting with materials like UHMWPE for non-elastic, high strength-to-diameter tendons.
I dont know if you'd have to weld the dyneema to the anchor points, though
stefanka
Roboy used dyneema tendons if I recall correctly. Fluidic actuators is another option. IMO, additional sensors and sensor fusion are necessary but this will raise the costs and demand to control software significantly. We are researching humanoid robots for quite some decades now and these problems are easily underestimated (similarly to autonomous driving). I doubt we'll see them in our houses very soon.
imtringued
I think you're misunderstanding the essence of the problem. If you use tendons, you'll need a neural network in your control loop that can learn continuously so that it compensates rope stretch and changes in friction through wear and tear.
A lot of problems in robotics reduce down to continual learning. Essentially all system identification tasks become obsolete the moment you have a self learning system and yet we have an AI industry preaching that AGI is around the corner without this "crutch".
mandeepj
The bigger or biggest question is - how much weight it can lift? If we assume it can lift half a pound, then what changes it’d require to make it lift 10/20/30 pounds and so on?
micromacrofoot
hands hold, arms lift — a hand without an arm isn't going to have much strength
horsawlarway
Yes, but this is "bring your own arm" so the person above you can easily build the arm out to whatever specs they'd like.
They probably want to know relatively important information like
- Breaking force (how much force will break a finger)
- grip force (How much force can the fingers exert to hold an object once closed)
- holding force (combination of grip force and material properties [ex - friction] that gives you an idea how much force can be applied to prevent slipping)
- closing force (How much force is exerted during closing [similar but distinct from grip/holding])
Or, with a lot less specific detail but still generally useful as a starting point...
- payload capacity (approximately how much can this safely manipulate)
What jumps out at me is the $135 bill of materials.
What a time to be alive!