Snap-Together Robohand

by MakerBot, published

Snap-Together Robohand by MakerBot Jun 17, 2013

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Look at your hands.

Hands are complex tools that grant humans a superpower, the power to transform imagination into reality. The power of our hands is unlimited. We can use them to throw a ball, climb a tree, or build a tool.

Not everyone is fortunate enough to have two hands.

Robohand is an open source tool created to help restore the superpowers of humans who are missing the fingers from their hand. The original version was created by Richard Van As and Ivan Owen.


The Snap-Together edition of Robohand is a simplification of the original Robohand. It lacks the rugged durability of the original, but is much faster and easier to build. This snap-together version is primarily an experimental platform to help people understand the mechanics of Robohand. I also hope it will serve as a catalyst for future development, and inspire others to pick up the project where I have left off.

Full Assembly Instructions can be found in the Instructions PDF

Source files are in SketchUp format and are available in: Robohand_Snap_Fittings.skp

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and how big should I print this? I tried printing it, but the fingers ended up pretty tiny.

Read page 4 on the PDF included in the .zip file for scaling.

This was easy to print, and easy to build. I quote:

"Impressive, most impressive."

I couldn't get it to work in Cura at first. I then opened it in Adobe Photoshop CC. After it loaded I exported it as an STL. Then I was able to open it in Cura.

For some reason, the stl files aren't being read by Cura. I can see them, but they aren't showing me how much time...

Did you ever figure out what was wrong with the .STL files? I am having the same problem with cura and wondering if you figured out what to do about it. I really want to make this and I only have cura. Thanks.

Nope, never figured it out. Makerbot Desktop sees it and loads a time. Cura just freezes when it tries to calculate a time. So odd...

I appreciate your work. I am thinking to write about it on my website : http://www.1click3dprint.com/blog.html/http://www.1click3dprint.com/blog.html/

My son was born 10 years ago without laft hand. Recently I found out about this bluprint, and I bought a XYZ 3D printer. But my printer took really long time to enter the slicing mode, then took another long period of time to tell me "slicing failed"! Can someone please help? or can someone please tell me what kind of program I should use to break up the grouping of pieces. I tried "123D Design", but not working.


Hi Sam. I also have a Da Vinci printer. I have a couple questions to ask before I can help you. Which model printer are you using? Have you updated your slicer software and printer software to the current versions? Have you tried printing other items and did you encounter the same slicing errors? What operating system is your computer?


Hi Adam, I have the Da Vinci AiO with the scan function. I have updated both XYZScan and XYZWare to the newest version from their website, but I didn't see any slicing software for downloading. And I have already print few simple items and they finished without any trouble. I'm using MS Windows 7 Pro edition. Thanks for the help!


Nice, I bought my Da Vinci 2.0 Duo about 2 weeks before they released the AiO online and now I'm jealous. The slicing software is XYZWare and I've found that it's not great and often deletes parts of my stl files when converting them to .3w format for printing. You seem to be doing everything correctly. Since you were able to print other items sufficiently it might be this particular file that's giving the slicer some trouble. What stl file(s) was/were giving you the slicing error? What scale were you using and what print settings? I'll try them out on my computer and see if they slice and then I can send the .3w files to you.

Hi, I found another hand bluprint which is called "cyborg beast". My son likes the cyborg beast better, and I was able to every parts except "finger_w_bumps" and "thumb_finger_w_bumps". It will pass through the slicing stage, but the finger look really weird. Can you try that instead? It will be great if u can slice those two files for me!! Thanks


There are a lot of results. Please post the url, what scale you're using, and print settings you would like (raft on/off, supports on/off, layer height, shell thickness, and infill density). After you do this I'll try to slice it for you.

"http://www.thingiverse.com/thing:261462", I'm using the scale of 130, raft on, support on, layer height 0.1, thick shell, infill density 50%. My email is [email protected], Thanks alot!

Cyborg Beast

How did they print?

Yes, it printed out fine! Thanks a lot!

Sorry for the delay. I'm mentoring my high school's robotics team and build season started on the 3rd so i've been extremely busy. I just emailed you the files, both the fixed stl files and the sliced ones. Enjoy!

One of the best hand modeling I seen ... !!!

I don't have a 3d printer:( I would love for my nephew to have a hand like this, he has 4 brothers and 1 sister and they all have both hands. My nephew was born with little to no fingers it brakes my heart to see him always needing help but he trys his hardiest to get things done.we don't have have much money and his parents are disabled vets so there is no way for them to buy a 3d printer and insurance does not help.

my name is william and i am the owner of 3dpsc.com
please contact me i i will print this hand for you at not cost.
[email protected]
I hope i can help

best regards

Owning a printer is a big expense. If you want some parts printed, and resources to help you out, get in touch with the folks at e-Nable. We will print your hand parts for free.
The Snap-Together Robohand is a brilliant development of the work of Ivan Owen and Richard Van As, by Michael Curry. Michael incorporated the snap-pin design into this cable-driven prosthetic device. That said, there are later designs that do a better job of fitting to a person. The Talon Hand, Cyborg Beast and Ody Hand are being fitted to people with good results.
If you can make it, come to "Prosthetists Meet Printers" at Johns Hopkins Hospital on September 28. Free admission, and your nephew will get a free device. He should bring family members to help him assemble his device.

I wish we could ...such a great opportunity and I'm very sad we can't make it.I live in Florida and he lives I California

What is better for This Printing PLA or ABS or Anythings else??
I want to make one for one poor boy..

Hmmm... You probably want ABS for the strength, but if possible, I think Nylon (with its intrinsic flexiness) might be a good idea. ABS should work just as well, though.

Hi peeps,
Got a very stupid question, once assembled, how do you actually attached the hand to the wrist?

Not a stupid question. I was wondering the same thing. I want to make one for a student at my school.

It's sad how makerbot is slow or doesn't answer questions around here.
Anyway, a custom wrist attachment needs to be measured and fabricated. A 3D scan of the student's arm and wrist would be ideal. I am not sure about fabricating it though, I don't think 3D printing is practical for that part. Polymer casting might be more suitable.

I live in Brazil, and I would like to print a full set. Could someone help me to print here in the U.S. and send it to me in Brazil. I'd pay in advance, because here in Brazil is much more expensive.
thank you

what would you use it for? Is it for yourself? Or a patient?

I would like to know how to get the exact demensions of a persons hand to get it to fit on

I believe answers are in the PDf under "thing files".

I printed this out, and it is looking great. I already have 3 people interested in ones to use. However almost all of the pins keep falling out and I'm not sure how to fix them. I will just hot glue them for the moment, but I was wondering if there was any way to get an editable version of the pints so I could tweak them. I am no 3d modeller but I could do enough to add a mm of fat to the ends to make them stick, or perhaps would it be possible to post the pints a lone with a bit more at the ends? Will post picture as soon as we have it together. Thanks!

if you have a rotary tool you can put a bit of filament in the end, spin it up to max power and "weld" the caps of the pins in, it's called friction welding, google it. also there is a skill builder on make magazine that showed me how. i suggest you try and dig it up

you can also use a soldering iron and melt some PLA over the ends

I printed and assembled all pieces but have one question. In the STL named "bridges" there are 4 extra pieces (the 4 smaller pieces) not seen in the build manual. What are they used for?

Those pieces can be mounted on prosthetic plastic, or in our case, leather. The large bridges are for demonstration purposes, and the smaller ones are for making an actual prosthetic device.

Wow, it sure would have been nice if the manual had mentioned you don't need to print the four small bridge pieces if you aren't attaching the hand to a prosthetic! That was a lot of extra wasted time, effort, and plastic. It could help some users if those extra bridges were in a separate STL file, too.

Otherwise, great project, and thanks for putting it all together! My 10 year old made it for Cub Scouts.

How can I get a hand made for my son without owning a 3-d printer? Not able to afford the cost of the printer. Is there a service that has them that you can use to have things printed?

Hi Debbie, you can get this stuff printed at http://shapeways.comshapeways.com
Also, you can buy a build it yourself 3d printer kit for really cheap. The printrbot simple kit starts at $300.

I just finished making this with and for my son. He loves it, and I'm just amazed to see him grabbing things with the left hand he never had. Thank you so much for your work on this project!

I seen ur Post Was Wondering If Ur Son Hand That You Made Still works?

Quick question. I am in the process of printing this, but one of the clip pieces and also a structure piece popped off the print surface during printing. I am new to this, is there a way to just print one replacement piece or do I have to print all of the clips again? Thanks! Replicator 2

How much does a printer cost?

You might try importing the .stl file into Blender or Sketchup, then take away the parts you don't need, and export the new .stl.
If you're in 3d printing, you should learn a 3d modeling program so you can modify your prints. Time well spent. Good luck!

If you are using a 3-d printer Dimension SST 1200es from Stratasys and you get the following error “STL has missing facets or reversed normals" just ignore it and
continue. The hand will print just fine!

ehuels is correct-- the design is effectively backwards. The fingers should grasp as the wrist extends. I think correcting this would involve routing the cables below the axis of rotation of the "wrist" joint.
Modifying the knuckle bridge would make the grasp more natural, but natural grasp is also due to the fact that fingers don't flex parallel to each other; they all point toward the base of the thumb. In addition, they have different radii of curvature (the small finger flexes more tightly than the ring which flexes more than the middle). Adjusting the knuckle bridge to accomodate this & individualizing the fingers to flex different degrees would make a much better grasp. Also, "fattening" the fingers to decrease the space between them would make the hand more functional.
However, I think the best function would be to achieve a pinch. This would involve getting the thumb to rotate around to meet the tips of the fingers, instead of just flexing.
Don't know if these are feasible, but would love to print one if you can design it....

Hello Skimbal
Thank you for the design. I'm getting a "STL has missing facets or reversed normals" error in all the robohand files. I'm using a 3-d printer Dimension SST 1200es from Stratasys. Do you have any idea?

Just printed and assembled first RoboHand. It was extremely simple. Thanks for making this available. This is for use by my son. One modification I made on the suggestion of our OT, was to mount the bridges upside down. This is the natural movement in order to grasp; i.e. wrist in the up position for grasp, wrist in the down position to release. This does cause binding on the thumb string, so I will be looking to modify for that. Also, I would also like to modify the knuckle bridge. I think if it was curved, instead of flat, the fingers would come together, more like a natural grasp. Will update if I am successful.

If you curve the knuckles, you'll have to curve the knuckle pins. Please upload your model if you do this!

Hello ehuels
Did you used the rep2 to print the hand? If not what printer did you used?

Is the design available in its original code; I would love to be able to modify this for some of my patients.
[email protected]

could you tell me the default dimensions of the parts in the structure.stl? I am having to try and print the components individually due to probs with print quality and my 3d design editor package has rescaled everything!

The 9 hole elements are 85mm long
The 7 hole elements are 63.3mm long

thanks - allnow printed and assembled. Just need to to connect string and elastic. Awesome build!

This is a far cry from the old hook. Congratulations!

This issue is an artifact left over from the SketchUp .stl export plug-in. Usually Netfabb will correct it, and it shouldn't cause a problem when using Skeinforge or MakerBot Slicer.

I printed the fingers and bridges - all good. The snap_pins.stl, however, is bad mesh. I fixed it in Netfabb studio and I'm about to try again... can I upload the repaired stl for you somewhere?

Very inspiring work.
I have been following this project since last year, but I was reminded of it yesterday when I heard about it on NPR:

Way to go!!! Keep up the fantastic work!

This is truly inspiring. Thank you for providing these designs for free. People like you are quickly changing the world for the better.

I will have to print one of these to show to students.

This smells of AWESOME-NESS!! Congrats! Good stuff!

An amazing reworking of the already inspiring original. Congrats to everyone involved!

Yes, it is truly inspiring. The original video brings a tear to this old man's eye. It is touching to know that mankind still has some humanity left in it in these last days.