Introduction: 3D Printed Air Tight Soft Robotic Pillow Actuator
This instructable is based on work from Mikey77, specifically: https://www.instructables.com/id/3D-Printing-Make-...
The idea was to create a 3D printed soft robotic worm that used the activation of individual segments to achieve peristaltic motion. This instructable details the fabrication of one segment. One of the novelties of this actuator is that it is created only using 3d printed ninjaflex with no sealant or post-processing(other than dissolving the PVA support).
1. A 3D printer capable of printing standard ninjaflex
2. Ninjaflex Filament
3. PVA Filament
4. A Pick
5. 4mm OD Silicone Tubing
6. 4 inch Zip Tie
Optional: A pump and valves for activation
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Step 1: Slicer Settings
The STL and CAD FIles can be found here:
I used Prusa Slicer but any slicer can be used, my settings for a Prusa Mk2s with a bondtech upgrade are below, I have underlined critical settings for achieving an airtight print, others can be played with:
Layer height: 0.2 mm
Initial Layer Height: 0.24 mm
Extrusion Width: 0.45 for perimeters and 0.4 for top solid infill
Top and bottom layers: 2
All Infill Patterns: Concentric
Speed: 20mm/s everywhere
Extrusion Multiplier: 1.3(This is one of the most important parameters and you will have to play with it)
Nozzle Temp: 240
Bed Temp: Ambient
Retraction Length: 0.4 mm
Lift Z: 0 mm
Next, you will need to insert a filament change before the top two layers in order to insert the PVA support. I did this in Prusa Slicer.
Step 2: Printing
Printing is straight forward, just make sure to add PVA glue if you are printing on PEI so it doesn't get stuck to your bed.
When the printer stops for a filament change, line up the nib on the insert with the hole in the actuator and push it in. It may require some force but the ninjaflex will give. The top should sit either flush with the current layer of the print or be very slightly below it. If it is too high the nozzle will crash into it, if it is too low the top layer will droop.
Make sure to reinsert the ninjaflex if it ejected and keep the nozzle clean until it resumes the print.
Step 3: Piercing the Hole and Dissolving the Support
Use a dental pick to pierce a hole in the hole for the tubing(this may or may not be necessary depending on your retraction settings) and use warm water to dissolve the PVA support material.
Step 4: Inserting the Hose and Securing It
insert the hose so it is flush with the main chamber opening and use a zip tie to secure it into place.
Step 5: Blow or Pump
Blow into the host or use a pump to activate the actuator!