Thursday, February 15, 2018

OpenSCAD: A Curved 3d Printed Lithophane


How can I wrap a flat surface around a cylinder in OpenSCAD. This was a question I asked myself. OpenSCAD doesn’t provide a ready made method so we need to write our own. Luckily we don’t have to invent the wheel here, others have done that already. Justin Lin has written a very handy tutorial on his website how to wrap a text around a cylinder.  In this project I took it a step further and wrapped a png image over part of a cylinder resulting in a curved image.

3D printed curved lithophane

Curved lithophane

It seemed like fun to combine this technique of wrapping with the 3D print of a lithophane. A lithophane is an engraved image on translucent material. Many 3D printers have already produced lithophanes sometimes with stunning results. For this experiment I’ll use white PLA because it  has excellent translucent properties.

Now first let me explain the basics on how to wrap a 2D image around a cylinder. First we create a circle out of triangles. These triangles are then extruded to segments to form a cylinder.  Next all segments of the cylinder are lined up in a row and the image is place on the far side but just within the limits of the segments. When we intersect the image with every individual segment and return the segments to their original position in the cylinder, a curved image emerges (see images below).

A circle created out of triangles
The extruded triangles form a cylinder
The segments are lined up in a row

Image placed on the far side of the triangles
The triangles returned to their original positions
The image intersected with the triangles and returned to their original position.

If you want to know more please watch my video. In this video the OpenSCAD script is explained and demonstrated. Also is shown how to import the stl file in Cura and what settings are used.

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