Give Yourself a (Robotic) Hand

If you Tweet it, they will come..... (and hopefully, Vote!)

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In this Instructable, we see how to design, 3D-Print and test components of a Robotic Hand.

If you like any part of this project, please vote for it and then email the link to everybody you know!

I enjoy writing programs.    I love building things.    I don't build robots for a living, but I do design them for fun and research.

My team and I are considering building a robot for the DARPA Robotics Challenge.   And today, we're looking at hands.

We need a realistic, reasonably priced robotic hand platform to test some ideas with.   When I shopped around, I found a lot of really good models that I didn't  have the budget for yet.   I wanted to see what could be designed using mostly 3D printed parts.   I'm happy to share our experiences with you here.

For this hand design, we want to be able to try lots of different types of servos, tendons, sensors, and control software.   I'm choosing to design the palm and fingers separately in an interchangeable and modular way, so the design can evolve with the project.

In this Instructable, I'll be focusing on the design and build of the fingers.  I'll spend a little time showing the palm design and talk briefly about the plan for tendons and servos.   The design was made using mostly OpenSCAD, and we debug some of the control systems in V-Rep in a later instructable.

If you are already familiar with OpenSCAD, you can skip ahead.
If you like, you can jump directly to the printed fingers.

Let's get started!...

Step 1: The tools to get you started...

 

If you Tweet it, they will vote.....

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The Tools Used:
     Brain  (I had one that I wasn’t using for anything else at the time...)
     Some paper and a pen
     My own hand (I had one handy)
     Digital calipers $9-$20 from Harbor Freight
     Computer (Linux, Mac, or Windows)

The Software Used:
     OpenSCAD Programmatic 3D Modelling Program
     http://www.openscad.org/

     MiniMagics STL File viewer
     http://software.materialise.com/minimagics

     STL View by ModuleWorks
     (Search the Android Marketplace) 

3D Printing Service Used:
     EngATech.com (ask for Tim)

How to Make it REAL:
While you are waiting for your download of OpenSCAD to finish, place your hand on a sheet of paper and trace the outline of your hand on the paper with the pen.  (Starts out easy, right?)

I placed a dot on the tracing at each location I thought I’d want a hinge or joint of some kind; at each knuckle of each finger and the thumb.  Afterwards, I used the digital calipers to measure (in millimeters) and make notes on the drawing of things like the width of each finger at the location of each joint. 

I also measured the distance between joints, the overall length and breadth of the palm and wrist.  Taking measurements from the paper tracing turned out to be much simpler than measuring with the calipers directly from my hand.   I was able to measure more carefully, and got better results, I think.

These measurements start to give you a sense of scale that you'll need when thinking about creating the model in the computer.  After you’re done measuring, its time to download and install the other program that you need to debug your model, MiniMAGICS.

You’ll use MiniMAGICS to review the exported STL file, and look for errors.  If MiniMAGICS shows your model to be “water- tight” then you are ready to email or upload your STL file to a service bureau for printing.

Comments

[mycroftxxx]

I wanted to thank you for bringing your hand samples by http://txrxlabs.org last Friday.  Hopefully, we can get the ultimaker-clone working again so that you won't have to use an Objet for your simplest parts.

[dgpreston]

Thanks, I appreciated the feedback and suggestions. I look forward to dropping by the lab to hangout and discuss quantum dots.

I'd love to get the word out to the whole lab to come read and vote.  

Is there a TxRx announcements channel where this wouldn't be considered  spam?

Would Roland know?