Flexible 3D Printing

For the course Technologies for Concept Design (TfCD) at the TU Delft we demonstrated an emerging technology through a prototype.

The starting point of our Instructable was the idea of printing hard and soft material in one print with an cheap 3D printer. It is possible with a very expensive printer (Connex 3), but what if this was possible with an Ultimaker? Building upon a project on Instructables.com (https://www.instructables.com/id/Super-flexible-duble-curvature-surface-laser-cut-p/) which was about creating double curved wood with the help of patterns.

Step 1: From Pattern to Print

As a first step towards an application with this double curvature implemented, we will try to identify the what settings, dimensions etc. works best.

Making the retrieved pattern usable for 3D printing was done with the help of Illustrator and Solidworks. In general, a wall thickness must be created to use the sketch in Solidworks and a printable object must be created in SolidWorks. The different steps in Illustrator, Solidworks and 3D printer (Ultimaker) will be shortly explained here below.

Steps in Illustrator:

- Select path (the pattern)

- Offset path (Object → Path)

- Minus Black (Effects → Pathfinder)

- Create a fitting stroke

- Create rounded corners (Effects → Stylize)

- Expand appearance (Object)

- Remove stroke Export to a dwg file (keep the settings in mind, we used inch : 1 on 1) (File → Export)

Steps in SolidWorks:

- Open file (File → Open)

Select: All Files (*.*)

Select the DWG-file Click:

Open Select: Import to a new file as 2D sketch

Click: Next (Check preview)

Click: Finish

- Boss extrude sketch Select sketch (Model)

Extrude sketch (Features → Extruded Boss/Base)

Type the thickness D1 (Direction 1)

Click: Ok

- Save as STL-file (File → Save As…)

Select: STL (*.stl)

Choose filename

Click: Save

Steps in Cura:

- Expert → Switch to full settings

- Basic → Quality: Layer height: 0.25 mm (max for Ultimaker2)

- Advanced → Quality: Initial layer thickness: 0.0 (same as other layers)

- Load STL-file Save toolpath → click save

Step 2: Prototype 1

The first prototype was made to test the pattern, if it would be flexible.

Based on this prototype we defined three variables that could influence the flexibility:

- The scale of the pattern

- The open space between the pattern

- The thickness of the surface.

We decided that this last variable should be kept constant to limit our variables.To demonstrate the difference in flexibility we made two models for each variable resulting in four models.

The dimensions we used were:
Prototype1:

- Total size: 90mm x 90mm

- Gap size: 0,7mm (before scaling)

- Scale: 1:2,38 (8 squares)

- Thickness: 2,5mm Test:

Step 3: Results

As can be seen in the images, the size of the patterns defined the flexibility in the models. Both models where the scale was lowered (model 1 & 2), the Ultimaker did not separate the material from the opening which resulted in less flexibility. For model 2, the initial layer was printed with insufficient open space, the rest of the print was supporting the flexibility of the surface.

Dimensions we used for these models are:

- Total size: 95mm x 95mm

- Space size: 0,7mm and 0,35mm (before scaling)

- Scale: 1:1 and 1:1,36 (19 and 14 squares)

- Thickness: 1mm

The open space between the pattern was also an aspect that was important but hard to print. For model 1 & 3, the gap was halved, which caused the Ultimaker to print them too close together. Model 4 was the most flexible, with the largest scale and largest open space between the pattern. The surface is very flexible, almost textile-like!

We can conclude based on our prototypes that the bigger the gap (space between the material), the more flexible the surface gets. We have insufficient information to draw a conclusion about the scale of the pattern because the small scale was too small to be flexible.

Step 4: Recommendation

Using this pattern within a product will have some consequences. The variables mentioned earlier influence the flexibility of the surface. If the designer wants a subtle pattern, the other variables will have to be adjusted to reach the wanted flexibility. With an relatively cheap 3D printer we demonstrated that it is possible to print flexible surfaces with hard PLA. This instructable is only the first step towards implementation of flexible surface in a product where we investigated the effect of certain variables.

Created by:

Ben Kromhout & Lukas Lambrichts