Has anyone tried to machining lumia effect wheels?

[laserist]

I've been curious about this possibility for a long time. I did find that the finish on an aluminum part I'd machined mad a cool star burst effect. Has anyone tried machining cast acrylic for lumia? Or anything similar?

[DanBarlow]

Yes, I had plans to use a graphite mill to make custom lumia molds for glass, and aluminum molds for acrylic.
Acrylic has a glass transition temperature, can be vacuum formed and hot pressed, and is cheap.
I have a prototype I made on a normal vacuum former using 2 liter bottle plastic, which gives a neat shadow effect. But I haven't progressed to making lumia wheels yet.

A good search term would be "Acrylic annealing". The pressing temperature is a little higher than that, but you'll get a good understaing of the temperature range and profiles involved.

[laserist]

I was envisioning machining and polishing the acrylic one off. I may just have a lack of imagination but from where I sit the lumia "market" doesn't seem to warrant mass production techniques.

[DanBarlow]

That's fair - I tend to overthink things. I have access to a great maker space so "make enough for everyone at SELEM" is kind of my default.
I have tried using a CO2 laser cutter in raster mode to "machine" acrylic. It sort of works, but the surface texture is grainy. Probably not an issue if you're going to polish it anyway.
I've also used a micro mill with a 1/16" ball end cutter to machine acrylic. The surface texture is frosted, and it is easy to overheat. Water cooling works well.
You can hand-carve with wood carving tools if you keep them very sharp.
I'm very interested to see what you come up with!

[mixedgas]

The correct tool seems to be a hand torch. Self-polishing. Use outdoors and upwind to avoid the VERY toxic fumes.

Or a diamond scriber if you have some robotics to drive it.

Now that I have a stabilized fiber laser in the red (MPB) I want to try a grating setup to record on Litiholo film.

Steve

[laserist]

Hi Steve, there are plasma polishers that I've seen used for cast acrylic polishing that are pretty cool. It's occurred to me that rolling the contour at temperature might be a way to go - depending on the surface tension effects. The one time I tried to make a dimple tube the surface tension was fierce.

[mixedgas]

I used to make oxygen and argon cold plasma microtorches at the University. That's tempting as the jet size can be miniscule. Put in on a GRBL driven stage...

Steve