Learning Single-Filament Printing Strength from Arachnids

If you can get over how creepy spiders can be there’s a lot to learn from them. One of nature’s master-builders, they have long been studied for how they produce such strong silk. What we hadn’t realized is that it’s not strictly cylindrical in nature. The spider silk exhibits intermittent expansions to the diameter of the — for lack of a better word — extrusion. This project uses biomimickry to replicate the strength of that design.

The print head is actually four extruders in one. In the clip after the break you can see the black center filament’s rigidity is augmented with three white filaments positioned around it radially. The use of this knowledge? That’s for you to decide. As with some of the most satisfying engineering concepts, this is presented as an art installation. As if the rhythmic movements of that print head weren’t enough, they mounted it on a KUKA and plopped the entire thing down in the center of a room for all to see.

The demo isn’t the only awesome bit. You’ll want to click the link at the top to see the exploded-parts diagram porn found half-way down the page. All is beautiful!

[Thank Jeramy via Atmel]

20 thoughts on “Learning Single-Filament Printing Strength from Arachnids

  1. oooooooooooooook….. ??

    Not a single result on whether it actually even increased the strength? And you could hardly claim this mimics a spider at all. Mimicking the spider silk ‘extrusion’ would have been more accurate to at least have a varying diameter print head since it is a solid structure. And bonus to have a strainer like device to push the plastic into tiny threads which then get twisted together by rifling in the nozzle and carefully controlling the temperature. Also, the bulbs are performed by a sphincter muscle which is spasming, restricting the flow, then releasing it. What makes the web strong is that it is like a mesh. And when you pull on it, it stretches. And when you release it, the mesh returns to its form. So like most other materials, the strength is due to the flexibility of both the material and the design and the ability to absorb stresses by transferring energy.

    This looks, nor I doubt performs, anything at all like a spider web. I don’t even know why they would make that claim.

    Art… that says it all, I guess.

      1. Nor do I see any comparison whether the pattern itself made a difference than just printing a thicker filament (5 strands thick.)

        With this design, all of the stress from pulling will be on that center thread. Once that snaps, then the other 4 strands will pull together to take the stess. But their only real anchor is the joints where they connect to the center strand. The whole thing would likely just “unzip” once that center strand breaks.

        My point was that this pattern has nothing at all to do with the features of the web. All they really did was create a machine that makes a wireframe profile of a spider web strand. It doesn’t mimic that strand and has none of the same properties or features. It doesn’t even look like they attempted to, either.

        The whole text reads like marketing speak, not engineering.

        1. I’m guessing the “knobs” are for better…”stickage” and not so much for structural support. A spider web is sticky after all and this would make the surface area larger whilst causing more crap for insects to get stuck in. Maybe “foot pads” for the spider?

  2. I could see using something like NinjaFlex for the center filament and PLA/ABS or a semi-flex for the outer filaments. That might create a stronger and flexible line. This is neat to look at, but it would be cool to see some practical applications of it.

  3. Variable die extrusion has been done in blow-molding for a long time, using a tapered plug in the extruder that varies the wall thickness of the tube of molten material. For a thin-diameter, solid material like this, getting a variable-diameter type extruder output would be tricky but not impossible (think of the variable nozzles on a modern fighter)

    1. Regular 3D printers control filament thickness (in at least one dimension) by varying extrusion speed. With a little craziness and maybe a few extra extruders you could probably do something like that here, at least within a limited range. Easiest to to if you’re tacked to something, but you might be able to use, say, a rigid-but-soluble filament as the thing to tack to, and vary the ratio between the extrusion speed for that filament and the rest. (I have to say I love the idea of extruding from a robot arm, if only I had one where I could locate the endpoint with enough accuracy.)

  4. it’s beautiful, it looks a little like a spinning field, but it doesn’t replicate spider silk making!

    For those that want to know why it is not silk:

    Spider webs are made of a number of different types of silk, each spun from a different spinneret. Each spider has many spinnerets of many different specialisations.
    The main types of silk in a web are structural scaffolding, named ‘ampullate’ from the shape of the silk gland that produces them, and for capturing prey, ‘aciniform’.
    The blobs you see on the scanning electron microscope image in the video are a water/ adhesive mix, only present on sticky aciniform silks= no strength. The blobs stick the silk to the prey.

    Real [ampullate] spider silk fibres are incredibly strong and tough due to their tiny diameter of 3 microns in or narrower, the flawlessness of their surface finish, and the very long protein chains they are spun from. When used to spin a web, the web will be strong.

    A note on extrusion: spider silk is not extruded. There is no muscle or other motive force in the spider capable of extruding such a viscous feedstock through such a small diameter whole. Any process that purports to mimic spider spinning, but uses extrusion, is not mimicking spider spinning. Rather, the fibres are pulled out of the spinneret (‘pulltruded’) by the spider’s legs or body weight, and chemical changes through the spider’s spinning duct modify the feedstock such that it forms the necessary chemical structure.

    In conclusion, to even approach the properties of silk spun by a spider, the result must:
    – Be pulltruded, not extruded
    – Consist of fibres no larger than 3 microns in diameter
    – Have a maximum breaking stress of over 700 MPa (for a large number of samples, please!)
    – Have an average strain at breaking point of over 18%

    hope that is of interest.
    Sources: Vollrath, F. & Knight, D. P.; Knight (2001). “Liquid crystalline spinning of spider silk”. Nature 410 (6828): 541–548, Agnarsson, Ingi; Kuntner, Matjaž; Blackledge, Todd A. (2010). Lalueza-Fox, Carles, ed. “Bioprospecting Finds the Toughest Biological Material: Extraordinary Silk from a Giant Riverine Orb Spider”. PLoS ONE 5 (9): 11234.

    1. Spiderman, spiderman,
      References whatever a spider can.
      Spins a web, factualised,
      Catches artists just like flies.
      Look out! Here comes the spiderman.

      mod edit to make the comment work with the song.

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