Progress on Parametric Printable Prosthetic

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So, I’ve been hacking away at an OpenSCAD sketch of the Cyborg Beast 3D printable DIY prosthetic.  At the moment I’m working on designing the left palm.1 I’m reasonably happy with the version so far.  I’ve also managed to separate out the cutouts for the hardware from the design of the hand itself.  The benefit to doing so is that it should later be possible to scale the hand up or down, but keep the hareware cutouts the same size.

It’s easy to print a hand, fingers, and thumb scaled to 110%, but finding Chicago screws that is 110% may be more difficult.  There’s still a LOT of work to do here, but I think this is a good start.  Below are the same three views of the two versions (OpenSCAD parametric and original Cyborg Beast).

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As I’m going through and replicating the design aspects of the Cyborg Beast, more design issues crop up:

  1. The grooves where the fingers fit into the palm are either tapered or flared in a non-uniform manner.  To get a better idea of this by reviewing the two pictures below.
  2. The holes for the elastic cord to cause the fingers to return to the open position do not appear to be of uniform diameter, uniform distance apart, or equally centered in the knuckle blocks.

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I can’t tell if these are critical design features2 or just design elements that don’t provide additional function or utility.  If you happen to know, your input would be greatly appreciated.

  1. And, really, once the left palm is done it’s an easy to mirror this part to make a “right palm.” []
  2. I’m guessing not []

10 Responses to “Progress on Parametric Printable Prosthetic”

  1. Nick Parker says:

    I’m almost certain those funny chamfers in the knuckle cutouts are inconsequential.

  2. MakerBlock says:

    @Nick: Great!! Thanks for telling me! I thought so too, but I didn’t know if they were there for some purpose like allowing a little extra wiggle room or allowing only certain fingers to be put in certain locations.

  3. Jorge Zuniga says:

    Nick Parker is correct Jay! Just poor designing skills :)

  4. David Orgeman says:

    Unless there is something of which I am unaware – and I do not think there is – the chamfers are of no importance. In fact, I would suggest they should not be there at all. I do not see that they provide ANY benefit other than looking nice (or they would if they were consistent). If it is just a uniform slot with no chamfer, then it is much more likely that any selected finger will operate correctly.

    I believe the holes are the same story. If it is possible to make them consistent, then I would recommend to do so. I think a lot of what you are seeing is simply that this was drawn in Blender rather than drafted in any sort of CAD.

  5. Jorge Zuniga says:

    Part of the problem Jay is that we use Blender, which is not an engineer CAD. The Blender rule of thumb is that “if it looks right, must be right”. I will keep looking at this website to see if i can help. There is very little “critical design features’, but I will let you know. Thank you for all the work you are doing!

  6. MakerBlock says:

    @Jorge: Thank you so much! This is really good to know. Finding out that there are few critical design elements is basically like being unshackled when it comes to designing. As long as the critical pieces are in place, I can move a lot faster. :)

  7. Laird Popkin says:

    Beautiful work! Having this in OpenSCAD is a huge win!

    I love the smooth curves that you’ve generated! Did you use one of the bezier curve libraries?

  8. MakerBlock says:

    @Laird: Nope! I know you’ve seen my other post, but I’ll link to it here in case anyone else has the same question. Basically, I used carefully placed, rotated, and deformed spheres and cylinders with judicious use of the hull command.

    http://makerblock.com/2014/03/openscad-intermediates-how-to-make-complex-organic-shapes/

  9. […] MakerBlock is one of the desktop 3D printing superstars who has taken up this cause. He has documented and shared a number of significant resources to catch you up to date on the collective volunteer R&D efforts so far. Here’s a resource he shared from those involved in university research into this topic: […]