Snap-Together Robohand

by MakerBot, published

Snap-Together Robohand by MakerBot Jun 17, 2013

Featured Thing!


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.

Recent Comments

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


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

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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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noyangohin on Jul 5, 2014 said:

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


Beufa on May 2, 2014 said:

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

WDC on May 18, 2014 said:

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

EdsonAmaro on Mar 23, 2014 said:

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

stevenarakaki on May 13, 2014 said:

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

mimi on Mar 21, 2014 said:

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

Anonymous on Jul 2, 2014 said:

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

jasonnolan on Jan 31, 2014 said:

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!

Killbox on Mar 13, 2014 said:

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

muckychris on Nov 4, 2013 said:

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?

profbink on Nov 14, 2013 said:

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.

DebbieM on Oct 29, 2013 said:

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?

ramai on Nov 4, 2013 said:

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

profbink on Aug 13, 2013 said:

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!

DS1 on Aug 9, 2013 said:

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

profbink on Aug 13, 2013 said:

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!

JorgeZuniga on Aug 3, 2013 said:

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!

aarongrand on Aug 2, 2013 said:

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....

JorgeZuniga on Jul 25, 2013 said:

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?

ehuels on Jul 24, 2013 said:

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.

profbink on Aug 13, 2013 said:

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

JorgeZuniga on Jul 25, 2013 said:

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

aarongrand on Jul 5, 2013 said:

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

jonbones on Jun 25, 2013 said:

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!

Skimbal on Jun 25, 2013 said:

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

mmmarkus on Jun 23, 2013 said:

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

jbernardis on Jun 22, 2013 said:


Skimbal on Jun 25, 2013 said:

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.

sahrchitect on Jun 21, 2013 said:

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?

NEATman on Jun 19, 2013 said:

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!

tombielecki on Jun 18, 2013 said:

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

tjfagan on Jun 18, 2013 said:

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

Fekinator on Jun 18, 2013 said:

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

pelkertron on Jun 17, 2013 said:

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

iowajames on Jun 18, 2013 said:

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.