May 22, 2016 | By Andre

It took me long into my life as 3D printing enthusiast to come to terms with the fact that post-production with paints and solvents are sometimes necessary to produce a better overall product. Once this realization hit, I got used to the idea of using acetone vapor as a way to smooth the lines off of my ABS based 3D prints.

Acetone is a strong, easily available and generally safe solvent that, when in contact with ABS plastic, will dissolve the ridges into a shiny-smooth finish. This process, done correctly, means you can easily get rid of the 3D print lines especially noticeable with filament based 3D printers.

The tricky thing is that even though acetone is generally considered safe, it is still a solvent that will quickly dry out your skin on contact or give you a headache with too much exposure. “Wear a mask!” My co-worker would always remind me when I’m smoothing out a part, nose exposed.

Mike over at EngineerDog decided he has a good solution to the flaws found in acetone smoothing that have always existed with his brilliantly named Ultrasonic Misting 3D Vapor Polisher.

As his Instructables entry illustrates, finish inconsistency, time consumption and even 3D print overexposure (resulting in the finely detailed features on the print melting together) are all annoyances when dealing with acetone smoothing. Additionally worth noting, some comments at the bottom of the hackaday page had more immediate concerns around the explosive properties of acetone when exposed to too much heat.

Mike's solution involves combining an ultrasonic humidifier, a acetone storing vessel and a pickle jar (the 3D print bathing chamber). The smoothing is possible when the vibrations from the humidifier create a fine mist of acetone droplets (with the density of the fog being controlled by a potentiometer). From there, a combination of an aquarium air pump (to push the mist around) and the enclosure housing the print provide a mechanism to smooth parts out with much more precision than what was common practice previously.

The Instructable is very careful to mention that although acetone is technically non-toxic in short bursts, it is highly flammable and jam packed with hazard warning signs on the container. For me personally, while acetone is not regarded as a carcinogen, a mutagenic chemical or a concern for chronic neurotoxicity effects, I have gotten mild headaches and sore throats if proper precautions weren’t taken. My co-worker is right: “Wear a mask!”

If you’re interested in making your own Ultrasonic Misting 3D Vapor Polisher the best thing to do is follow the steps on the instructables page and go from there (roughly $40 total if you’re creative with your purchases). The entire project involves the disassembly and cutting down of a humidifier and a lot of glueing and rewiring of others so it’s not a five minute operation. This said, if it’s the best method, it might be worth the effort.

Lastly, the fascination of acetone smoothing held by Mike lead him to do some strength related tests with a smoothed 3D print vs. an equal but unsmoothed 3D print and the results surprised both him (and me). His assumption going in (as seen in the video below and this here document) was that acetone smoothing would increase the strength of the parts. He found out it had the reverse effect. In fact, on average, acetone smoothed parts were roughly 24% weaker.

In the end, if I wasn’t so deeply invested into 3D printers that use PLA as the preferred material (acetone doesn’t do anything to PLA) I would certainly jump at the opportunity to make my own copy of The Ultrasonic Misting 3D Vapor Polisher. Partly because of it being practical, partly because of its groovy name.



Posted in 3D Printing Technology



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Michael Graham wrote at 7/13/2016 2:37:51 AM:

There is an updated version of the ultrasonic polishing machine out now!

Jake F wrote at 5/24/2016 7:50:12 PM:

I would suspect the acetone is penetrating the material and reducing the molecular weight of the PLA which will indeed reduce the mechanical properties of the material.

Jon S wrote at 5/23/2016 7:47:11 AM:

This is the same technique used by the Polymaker Polysmooth PVB resin and Polysher machine. The only difference is that that is alcohol-based.

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