Acrylic - is an optical quality cut possible?

I need to make some light pipes, I cut some test pieces but under magnification, the cut is serrated, which diffuses the light source to the point of being unusable. Before I spend time and material on adjusting the cut settings, I’m wondering if it’s even possible to get near-perfect cuts, or am I going to have to polish by hand?

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Polishing by hand is going to be your best bet – either flame polish or fine-grit papers. For light pipes, I’d think flame polishing would be faster and easier, though having the right kind of torch might be the trickiest part.


Thx… I have several options at my disposal when it comes to flame - butane, MAP, propane or methane. I’ll wait to see if anyone has other suggestions/experience,…

I have done a little flame polishing on flat pieces before and I am skeptical that it will round those serrated cut edges enough to create a nice optically flat surface. No reason not to try though.

Can you alter your design so that the surfaces which need to be optically flat are only cut on the machine’s X and Y axes? If you are cutting with only one stepper motor at a time I’d expect the serration to be reduced or eliminated.

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Sandpaper. Please see Ben Krasnows youtube video where he makes acrylic optical elements and experiments with polishing methods.


Yes, it is possible. I worked all weekend on a similar project. The laser cut finish will give you a good lightpipe finish if all you are looking for is light transmission. I ended up using a file on the surface to give a cloudy finish to try to get a dispersed output but it didn’t work all that well.
In the past I have also done edge polishing. I used abrasives from a company called MicroMesh that makes abrasives to refinish aircraft windows and I was able to get a perfect finish, though it took a lot of work.

Also see other threads here that talk about using a defocused final pass with acrylic.

Yeah, but that’s vertical, such as using 3D Carve to make a shape in acrylic, then clean out the dust and do a ‘defocused’ pass over it, to smooth out the material.

Though now I wonder - could you do something similar by cutting a shape, removing it from the surrounding material, then doing a cut pass just a bit offset from the original cut, so the heat from the laser might smooth the original cut?

That’s a good idea - I can rotate the design to accomplish that.

Lots of ideas, and I’m not averse to polishing by hand, but if there is a way to produce what I need straight off the machine, I’d like to explore that because if this works out, it might lead to volume production.