May 9, 2015 | By Alec

Anyone with a bit of experience in desktop 3D printing will know of the technology’s great potential and of its unfortunate limitations. In that last category, one of the most common complaints is the grainy finishes on 3D printed objects, that invariably reflect the layering pattern it was built in. Now there are forums full of tips and tricks on how to polish your 3D printed surfaces, but one 3D printing nut called Michael has developed a very interesting method to do so: a vapor polisher, built from an ultrasonic humifier.

As Michael explains on the Instructables page for his nifty invention, using solvents to get rid of layers is a tricky business. Options such as boiling solvents in a pot can be very dangerous, while cold treatment methods can be very time consuming. Another fan favorite, dipping parts into solvent, meanwhile is so unpredictable you quickly end up destroying more than the outermost layers.

All of these were unsatisfying. ‘All I wanted is a machine that lets me quickly drop parts into a transparent container and be able to press 'go' and have the machine produce a predictable finish on its own. I do not want to have to put together a really involved setup that may be a fire hazard, fume hazard, or something that produces unpredictable surface finishes. Essentially I want something as convenient as a microwave,’ he says. And that, in a nutshell, is why he built the Ultrasonic Misting 3D Vapor Polisher.

Now this machine looks like something out of a madman’s laboratory, but it is actually rather simple to build. As Michael explains, the key component is an ultrasonic humidifier. ‘This uses a piezoelectric transducer (like a speaker) to create a high frequency mechanical oscillation in a liquid. This vibration forms an extremely fine mist of droplets in a fog/mist. The density of the fog is controlled by varying the intensity of the vibrations via a potentiometer,’ he explains.

And by hooking that mist-producer up to an aquarium airpump, Michael has managed to create a misting chamber in which you can simply place a 3d printed part to coat it in acetone/water mist. ‘This airflow keeps the air moving inside the finishing chamber, which helps produce a consistent finish on the part,’ he says. Alternatively, if you need to give extra treatment on a single surface you can always manually direct the pump at that location. And through the inclusion of a simple timer, Michael has been able to get consistent finishes every time.

As acetone is relatively harmless in small doses, this setup can be used indoors with caution. If you would like to use other solvents (and you might, depending on the materials you 3D print in), take it outdoors! Acetone is perfect for ABS, but other materials need other solvents.

Now making one of these Ultrasonic Misting 3D Vapor Polisher isn’t that difficult, though you will need quite a lot of components: an  Air Pump & Check Valve, an 8"x6"x3" Project Box, an Ultrasonic Humidifier, an Airtight Glass Jar (which will become the misting chamber), a brewing airlock, an empty paint can and quite a lot of tubing. Adding a mechanical timer, finally, will make everything a lot more easier. For assembly, be sure to follow Michael’s careful guide, as you don’t want to get a face full of acetone.

The results: untreated ABS print on the left, 15 minute treatment in the middle and an hour on the right.

And that’s really all you need to make your 3D printed parts smoother than ever. While you shouldn’t expect marketable-quality results immediately, it will definitely make your creations more displayable than ever. Just one word of warning: acetone treatment can slightly decrease the sturdiness of 3D printed objects, as Michael found out after some experiments. ‘The testing was pretty conclusive that treating abs specimens with acetone vapor caused them to lose strength despite having given the specimens a full 24 hours to dry out,’ he writes. ‘My highly speculative guess for the resulting loss of strength is that the exposure to the solvent caused a permanent chemical change to the surface of the parts resulting in a softening affect.’ But this shouldn’t scare anyone off from giving their planters and 3D printed yoda’s an extra smooth finish.

The Ultrasonic Misting 3D Vapor Polisher in action.


Posted in 3D Printing Applications


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John O wrote at 5/12/2015 2:22:00 PM:

Might be interesting if a different fill or solid fill would show the same failure. Lots of void in this one and not much connection between fill components

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