We Can Now 3D Print Slinkys

A mark of a good 3D print — and a good 3D printer — is interlayer adhesion. If the layers of a 3D print are too far apart, you get a weak print that doesn’t look good. This print has no interlayer adhesion. It’s a 3D printed Slinky, the kind that rolls down stairs, alone or in pairs, and makes a slinkity sound.¬†Conventional wisdom says you can’t print a Slinky, but that didn’t stop [mpclauser] from trying and succeeding.

This Slinky model was made using a few lines of JavaScript that output a Gcode file. There is no .STL file, and you can’t edit this CNC Slinky in any CAD tools. This is also exceptionally weird Gcode. According to [mpclauser], the printer, ‘zigzags’ between an inner and outer radius while constantly increasing the height. This is the toolpath you would expect from a 3D printed Slinky, but it also means the usual Gcode viewers throw a fit when trying to figure out how to display this thing.

All the code to generate your own 3D printable Slinky Gcode file is up on [mpclauser]’s Google Drive. The only way to see this print in action is to download the Gcode file and print it out. Get to it.

32 thoughts on “We Can Now 3D Print Slinkys

  1. Just tried to print this. The gcode download is fairly useless unless you happen to have the same filament/printer/nozzle as the author, so be prepared to try to compile this. Also worth noting, since the article’s writer doesn’t seem to know the difference, this is a java program, not javascript.

    1. glad to hear you can visualize the gcode. I was surprised when the write-up said it was not view-able. I’ve had no trouble with both Repetier-Host, and gcode.ws(first result when googling gcode viewer)

    1. Presumably yes, if you used a powder based machine and had a small amount of distance between each layer and didn’t mind printing a $2,000 stainless slinky. Would probably take a bit of testing.

    2. If using a SLS, it would either require an incredibly small layer height, or would have a stepped appearance. i’m moving the vertical axis at least every degree of rotation that’s 360 steps per turn in the coil. if i understand the current state of SLS each layer would have to be flattened off for the entire build volume. by the time your slinky is half way done, someone will have invented a better way of printing in metal.

      A modified code could be made for SLS purposes that would print wide overlapping arcs for each layer, giving a somewhat spiral staircase appearance to the slinky, but should work. I’ve not tried this on my FDM printers for two reasons one, the long arcs would droop and probably fuse, and two, my firmware cant handle the G3 command. SLS would have a bit of un-sintered metal to support the gaps.

      I would love to try some copper bearing filament to try and get that metallic sound, I’ve got access to ceramic kilns to sinter the end result.
      anyone know if two prints made of copper bearing filament will go clink when hit together?

    1. in theory yes, it could be printed on it’s side, with incredibly thin parts incredibly close together. however there would be a couple of issues
      1. the spring would be at equilibrium stretched to the size it was printed at, not in a fully collapsed state. with a small enough difference, you would not notice when the slinky was sitting flat, but it would definitely affect the overall characteristics.
      2. the printer would have to be honed in to perfect operation, if there is any stringing in travel moves, it wont work. if there is any movement of these extremely thin pieces from inertia, or warping, subsequent layers wont stick right. press too hard when extruding the next layer, and the structure buckles, press too soft and the new layer wont stick.

      finally, printing a slinky on edge, as is with any sliced print, requires freshly extruded plastic to stick well to plastic that has cooled off, where as with my method, the freshly extruded plastic is only being asked to stick to the plastic that was extruded a moment ago, and specifically not desired to stick to the cooled off plastic.

  2. This is great!
    I have always thought that writing code to generate GCode could make better prints than slicing 3d models.
    Kind of like the difference between WAV and MP3

  3. Have been holding out hope for a good while now, but this nails down the impression these machines will go down in history associated with the vac-u-form, easy-bake oven, and chemistry set. At best they’re matching lincoln logs and legos, but not quite up to the erector set yet.

    Might get some attention if you could print bugs with something edible…

    … but hey! I do hope to be proven wrong and will be first one standing in line when you do. Would really like to see this be THE thing!

    I can be ignored though…. I’m also waiting for Mr. Fusion.

  4. To be honest, I don’t get why no one hadn’t done this before. A slinky happens to be the same “path” as helical milling, or thread milling. It’s the exact same code- radial moves from an origin point moving up or down in Z axis the same amount. I honestly can’t believe no one ever noticed this? Of course, the helical lead in and out of thread milling isn’t here, but it’s just a helix. Really, no one noticed this before? The G code to do this is utterly basic

    1. FDM printing isn’t like milling and sure this may have been tried before but few are brave enough to post their work. The trouble with 3D printers is stuff tends to fuse together so the trick is to find a method that is successful.

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