True spherical engraving/cutting

I’m a woodturner and looking to engrave or pierce hollow wooden sphere.

Does anyone know the best way to unwrap a sphere so the pattern can be seemless on the project?

To get around the extra axis of curvature I’m looking at the rotary attachment by ortur. This is a chuck version, where the head can be tilted up to 180 degrees.

I’m thinking rings could work, adjusting the tilt manually between 2 jobs.

Hi Ruben,
Given the fixed nature of the X axis, true Spheres will be a problem.
You would need a 5-6 axis type of machine to do a full UV unwrap - so to speak - of the texture.

Cylinders or conical shapes can be done within LightBurn it.
On latest version you even have a taper compensation tool for - for example - the Yeti cups.

Rotary work is - however - one of the most practice and trial an error. Achieving a seamless full wrap is … herculian at times :smiley:

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I figured it wouldn’t be straight forward :slight_smile:
I thing I’ll start with several jobs of conical “rings” and see where that gets me.

Thanks for the info.

I would definitely baby step into it.

And save a lot of coke cans for experiments!

no worries I’m a woodturner, I have plenty of scraps to turn cylinders and spheres for testing :smile:

I have not done this but let me offer an alternative perspective. Instead of rings, consider longitudinally cut shapes cut end to end.

Similar to this:

Here’s my thought process:

  1. While it won’t be simple, this should simplify work holding. Trying to hold rings of varying size would likely be challenging and would require a different setup for every ring shape. This would allow you to have a single setup for every shape.
  2. This should allow easier mounting where the spherical center axis is the center of rotation on the rotary. That would allow for a consistent focal distance to laser during every rotation. This reduces the focusing issue to only changes along the axis of rotation which would be easier than tearing down the setup. If you have a mechanized Z-axis you could semi-automate the focal changes required.
  3. In terms of the size of the slices to me that would be determined by clearance from laser to material. As long the rotary+material can clear the laser module at full rotation required then you want to go as big as possible on the slice size, again to reduce the number of setup changes. If you can away with a semisphere that could ideal but if you want a continuous engraving then you may need to go to thirds or quarter slices.

thanks for the info! I’ve also thought of these slices, but the mapping to make each slice match and how to move the sphere to the next slice without overlapping wasn’t clear yet.

Although now that I think of it. I can just use my lathe’s indexing to draw pencil marks and then use those for framing… interesting :slight_smile: