Marionette 3D Printer Replaces Linear Rails With String

In the early days of FDM 3D printing, the RepRap project spawned all sorts of weird and and wonderful designs. In the video after the break [dizekat] gives us a throwback to those times with the Marionette 3D printer, completely forgoing linear rails in favor of strings.

The closest thing to a linear guide found on the Marionette is a pane of glass against which the top surface of the print head slides. A pair of stepper motors drive the printhead in the XY-plane, similar in concept to the Maslow CNC router, but in this case two more strings are required to keep the mechanism in tension. To correctly adjust the length of the string across the full range of motion, [dizekat] uses a complex articulating pulley mechanism that we haven’t seen before. The strings are also angled slightly downward from the spool to the print head, holding it in place against the glass.

The bed print bed is also suspended and constrained using string, with no rigid mechanical member attaching it to the frame of the printer. Six strings connected to the sides and bottom of the bed frame constrain it in 6-DOF, and pass through another pulley arrangement to three more strings and finally to a single stepper driven belt.

We can’t see any particular advantage to forgoing the linear rails, especially when the mechanisms have to be this complex, but it certainly make for an interesting engineering challenge. Whatever the reason, the end result is fascinating to watch move, and the print quality even looks decent.

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Learning Through Play Hack Chat With Greg Zumwalt

Join us Wednesday at noon Pacific time for the Learning Through Play Hack Chat!

You may think you’ve never heard of Greg Zumwalt, but if you’ve spent any time on Instructables or Thingiverse, chances are pretty good you’ve seen some of his work. After a long career that ranged from avionics design and programming to video game development, Greg retired and found himself with the time to pursue pet projects that had always been on the back burner, including his intricate 3D-printed automata. His motto is “I fail when I decide to stop learning,” and from the number of projects he turns out and the different methods he incorporates, he has no intention of failing.

Please join us for this Hack Chat, where we’ll discuss:

  • Lifelong learning through play;
  • Toy-building as a means to skillset growth;
  • Sources of inspiration and getting new ideas; and
  • What sorts of projects Greg has in the pipeline.

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Learning Through Play Hack Chat and we’ll put that in the queue for the Hack Chat discussion.

join-hack-chatOur Hack Chats are live community events on the Hack Chat group messaging. This week we’ll be sitting down on Wednesday, March 13, at noon, Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

New Contest: 3D Printed Gears, Pulleys, And Cams

One of the killer apps of 3D printers is the ability to make custom gears, transmissions, and mechanisms. But there’s a learning curve. If you haven’t 3D printed your own gearbox or automaton, here’s a great reason to take the plunge. This morning Hackaday launched the 3D Printed Gears, Pulleys, and Cams contest, a challenge to make stuff move using 3D-printed mechanisms.

Adding movement to a project brings it to life. Often times we see projects where moving parts are connected directly to a servo or other motor, but you can do a lot more interesting things by adding some mechanical advantage between the source of the work, and the moving parts. We don’t care if it’s motorized or hand  cranked, water powered or driven by the wind, we just want to see what neat things you can accomplish by 3D printing some gears, pulleys, or cams!

No mechanism is too small — if you have never printed gears before and manage to get just two meshing with each other, we want to see it! (And of course no gear is literally too small either — who can print the smallest gearbox as their entry?) Automatons, toys, drive trains, string plotters, useless machines, clockworks, and baubles are all fair game. We want to be inspired by the story of how you design your entry, and what it took to get from filament to functional prototype.

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