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Author: dougw
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Sixth Sense GraffitiBot Hydraulics - Blog 18

dougw

The GraffitiBot is now fully functional for printing graffiti although there is still a lot of room for improvement of the print head nozzles.  It took quite a bit of work to get the hoses to curl properly without kinking. The kinks were making it difficult to purge air bubbles from the hoses.

It was also very difficult to get each individual nozzle to be clear and smooth. The pores are so small, any tiny whisker of plastic completely messes up the output. I have some tiny drills, but they can leave small whiskers and they are so delicate, I broke 2 of them in the manifold (and couldn't remove the broken bits).

I had printed and tested the manifold and nozzles early in the project so I knew they would be problematic. I ordered proper dispenser nozzle tips when I discovered the issues, but they have not arrived yet, so the machine is stuck with a pretty low performance nozzle arrangement until they arrive.

Here is a little video showing that the software is all working well and the pumps are working under software control:

I will try to squeeze in a couple of runs trying to print graffiti just to show what this nozzle set up can do, before doing a wrap up blog as this is the last day I can work on this design challenge.

 

Relevant Links

Sixth Sense Design Challenge: About This Challenge

Sixth Sense Design Challenge: Technical Documents

Sixth Sense Design Challenge

KMT32B Magnetic Angle Sensor

 

GraffitiBot Project Blogs

Sixth Sense GraffitiBot - blog 1

Sixth Sense - Kit Unboxing and Other Parts - GraffitiBot blog 2

Sixth Sense - Sensor Circuits - GraffitiBot blog 3

Sixth Sense - Interfaces - GraffitiBot blog 4

Sixth Sense GraffitiBot - System Interconnect - blog 5

Sixth Sense GraffitiBot - Wheels & Motors - blog 6

Sixth Sense GraffitiBot - ST Sensor Tile App - blog 7

Sixth Sense - Load Cell PCB - GraffitiBot blog 8

Sixth Sense - Magnetic Angle Sensor - GraffitiBot - Blog 9

Sixth Sense - LCD Interface - GraffitiBot - blog 10

Sixth Sense - Pump Controller - GraffitiBot Blog 11

Sixth Sense Main Drive Motor - GraffitiBot - blog 12

Sixth Sense Motor Controller Mods - GraffitiBot blog 13

Sixth Sense - RTD - GraffitiBot Blog 14

Sixth Sense Mechanical Design - GraffitiBot Blog 15

Sixth Sense GraffitiBot Motor Wiring - Blog 16

Sixthe Sense GarffitiBot - First Dry Run - Blog17

Sixth Sense GraffitiBot Hydraulics - Blog 18

Sixth Sense GraffitiBot Printing Graffiti - Blog 19

Sixth Sense GraffitiBot - Summary - Blog 20

Anonymous
  • in reply to weiwei2

    Google McKibben Artificial Muscle.

  • Nice update Douglas.

     

    Have you thought of going to a piezo electric nozzle from an old inkjet printer?

    It might give you better droplet control.

     

    DAB

  • in reply to weiwei2

    Hydraulic and pneumatic actuators are common in providing muscles for industrial robots and machines, but it would be fun to find a way to use hydraulics more simply to emulate muscles as you suggest.

  • i have never have my hand on hydraulic, looks fun to be used one day. i wonder if there is hydraulic to move object like human muscle (contract, expand alike)

  • in reply to 14rhb

    Good suggestion. I might try it with some needles - those drills get stuck in the material pretty easily.

    Needles are not brittle like drills, if you wiggle them, they don't break.

    My attempts so far have shown that PLA is a weird material. When it is heated enough to deform, it gets very rubbery and as soon at the deforming tool is removed it just springs right back. If you leave the deforming tool in place it can get stuck, messing the whole area up.

    Also if too much heat is applied, it is easy to make the hole too big and it is really hard to make the hole small again...

    I wanted to get some runs in before potentially making the nozzles worse.