3D Printing Flexible Grids

We’re constantly looking for new examples of what we can print using our 3d printer.  I tend to enjoy the prints that have lots of little parts that can move.  It’s great to print something with over 600 parts, and not have to put all of those pieces together.  We worked on a part in the past that had a ball and socket joint and we found that we could minimize the gap between two pieces to .1 mm (.00394″) and they would still be separate after printing.  Recently we made a Grasshopper definition that used the grid components to create a set of flexible grids.  The three grids we used were triangular, square, and hexagonal.

A ring is created at each node in the grid.  A perpendicular set of rings are then created at the intersection of the grid line and the node ring.  The last step creates a pipe around each grid line.  The Alaris30 is an inkjet based print and with each slice it prints the inner area of the geometry.  This allows us to avoid having to boolean all of the intersecting geometry together as long as each object is itself water-tight.  This modeling approach doesn’t work well with SLS (Selective Laser Sintering) and SLA (Stereolithography) printers because they use lasers to fuse the model material together so if there are two overlapping objects than that overlap gets zapped twice potentially making a mess.

We ran into an issue with meshes that were too large for Objet Studio to handle.  The computer that is connected to our printer is an older box with only 1gb of RAM.  The print failed every time a job was sent with a mesh over 500mb (lots of smooth rings = big mesh file).  One way around this was to use Objet Studio on a different computer with more RAM and then export a packed job which could be opened with the Job Manager on the computer connected to the printer.

The fascinating experience with these prints has been physically learning how each of the grid types adjusts and conforms.  Initially the gap between rings is fairly tight from some residual support material which causes the grid to hold any shape that it is put into.  Unfortunately, after playing with them for awhile the support material works its way out and the gap gets opened up to the modeled 0.003″.  The print then acts more like a soft piece of fabric.  We intend to play with shrinking that gap of 0.003″, but we’re guessing that the parts will begin to fuse together below that value.

It’s great to have tools like Kangaroo Physics which allow grids to be digitally conformed to surfaces, but there’s definitely a benefit to being able to also do it by hand.  Now I just have to find someone at Boeing to print a version in titanium.

12 Comments

  1. Randolph M. Fritz says:

    Neat. Sure beats molding them and trying to assemble them by hand!

  2. scrawford says:

    The molding/casting process was a good learning experience but this is a lot faster though it could get costly to make anything bigger than a sheet of paper.

  3. Daniel Piker says:

    Great work!

    Would love to see some videos of how these things look when they move around.
    Have you seen this shapeways post about ‘digi-fabrics’:

    http://www.shapeways.com/blog/archives/525-White-Strong-and-Suuuuper-Flexible..html

    I think this is a really interesting area to explore.
    It might also be nice to try 3D-printing some auxetic materials something like the ’tile magic’ series on this page:
    http://www.shapeways.com/blog/archives/525-White-Strong-and-Suuuuper-Flexible..html

  4. Daniel Piker says:

    oops, wrong 2nd link there – I meant to post this one:
    http://www1.ttcn.ne.jp/~a-nishi/z_g_toy.html

  5. scrawford says:

    Daniel,

    Thanks for the excellent links. I hadn’t seen the Shapeways post on digi-fabrics but had seen other examples of chain mail and RP fabrics.

    The tile magic examples on the Geometric Toy page immediately made me think of Hoberman Associates new shading systems.
    http://www.hoberman.com/portfolio.php

    This started as a fun experiment with the printer but has made me in interested in seeing where else it can go. I’ll see what I can do about getting a video together of moving these prints around.

  6. Dylan Oliver says:

    Awesome work Scott-

    Push it to the limit!!

    -Dylan
    Kemeera

  7. scrawford says:

    Dylan,

    I’ve been decreasing the gap between the pieces and at this point we’ve been able to successfully print a moving part with a .0008″ modeled gap.

    No idea what the actual gap is but on the next run I’m going try a gap of 0.0″ to see what happens. The contact area between the two perpendicular rings is so small I think it’ll still move though it might need a bit of extra coaxing.

    Scott

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