Assignments Goals

• Make a machine, including the end effector, build the passive parts and operate it manually

Week's Lectures

The PluriBot

For this week's assignment, after a brief session of brainstorming, we decided to design a CNC machine to automatically fill bubble wrap with fluorescent liquid. The idea is to combine pixel art with gel tonic water, recycling used bubble wrap to make something artistic.
The name we gave to our machine is because the bubble wrap is commonly called Plurball as well.

Since we planned and built everything together, we shared the effort, so that everyone of us had the same knowledge of the machine.

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In the Work files links you can find the design file, in Rhino, with a 3D model and the whole nested panel to create the machine from scratch.

Work files links

Mechanical movement

Since we had to use the motors included in the kit, that are motorized lead screw steppers, we decided to build an X/Y gantry system, taking cue from the Ultimaker Original 3D printer. In this kind of system, the extruder (or in our case the actuator) is placed in the intersection of the lead screws and moves along the X/Y directions, thanks to the force applied by the motors to it.

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After mounting the X/Y system, we tested it moving the lead screws by hand and checked that everything worked as expected. The linear rails we received in the kit were really awful, so we swapped them with 8mm straightened steel linear rails, and the movement improved really much.

3D Model

Frame

To make the machine more solid and reliable, we designed a frame that can be laser cut from a sheet of 4mm MDF, and mounted without glue or screws just by press-and-fit. The result was a sturdy square frame, with holes to keep in place the linear rails, and with openings on all sides to make easy the assembly of the whole structure.

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When the assembly was complete, we tried once again to move manually the motors and we checked that bearings were sliding smoothly on the rails. To stress a bit the system, we even tried to move the lead screws attaching an electric screwdriver to them and driving them "speedly".

3D Model

Needle Actuator

The most complex piece of the machine was to design a compact and functional needle actuator to cut through the pluriball and inject the material. At the beginning we thought to use a 3rd motorized lead screw to move up and down the needle, but we abandoned this idea since this solution seemed too bulky and cumbersome.

So we racked our brains and we came up with a more compact design based on the use of a servo motor to push down a structure holding the needle, and on the use of springs to make the structure go up.

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In this way we managed to fit the needle, the rubber hose for the liquid, the servo motor, the tiny rails and the springs all inside the "extruder box", exploiting the free space between the leaded screws.

Moreover, to make the movement of the servo arm more centered compared to the plane that pushes the needle, we designed and laser cut a small plexiglass arm to screw on the original one.

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3D Model

Syringe Actuator

The last piece of the Pluribot was to design a motorized syringe to inject the gel inside the bubble wrap, so we decided to use the last motorized lead screw to press the syringe plunger of an exact quantity.

After a bit of tinkering with linear guides and bushes we designed a simple box in which is possible to easely put on and remove the syringe.

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3D Model

Full machine

The final part was to assemble everything together and try the whole system. Everything worked ok and the assembly was completed in a couple of hours.

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Moreover you can see a video of the movements of the full machine HERE

3D Model

Assignments Outcomes

• Work and communicate effectively in a team and independently
• Design, plan and build a system
• Analyse and solve technical problems
• Recognise opportunities for improvements in the design

Have you:

explained your individual contribution to this project on your own website
shown how your team planned and executed the project
described problems and how the team solved them
listed future development opportunities for this project
included your design files, ‘hero shot’ photos of the machine and a short video of it operating