It's been over a year since I published a popular Instructable about ultrasonic misting ABS 3D printed parts with acetone vapor. A couple months ago I was inspired to revisit this project by the professional 3D printing "Polysher" machine on Kickstarter.
In this instructable I've redeveloped my original ultrasonic polisher proof of concept into a more polished and professional tool with key functional improvements.
Additionally, after perfecting the machine I performed experiments involving mechanical testing of acetone polished ABS specimens in various orientations; and I observed some very interesting results! (See final step)
In case you didn't see the original project, my goal has always been to build "...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."
The original project involved repurposing the electronics from an ultrasonic water humidifier so that they could be used for acetone instead. The acetone mist/fog was then blown through an open system and filtered through a water bowl before venting into the room.
The result of that project was a functioning polisher that I could operate inside the house, but not without a bit more effort than I had wanted. In practice the water in the filter would readily absorb the acetone, but the water needed to be changed after every use and the process was wasteful with the acetone. Additionally, the form factor of the entire machine was not visually pleasing or fun to lug around.
So after a couple design iterations I've improved the old design into something even more awesome!
The user interface is now simply an ON/OFF switch and a single momentary button for 'go'. The new design now uses a closed pumping system and has been optimized for maximum fog production; So it is completely sealed allowing for indoor use, it takes less time, consumes less acetone to do the job, and no water ever needs changing!
And finally the entire machine is built into one single transparent assembly, so it looks good and is easy to transport to Makerfaires! (See you at PDX-mini this fall!)
The first thing that must be said here is that the solvents used by this machine are flammable and irritating to your eyes, skin, and respiratory system. Always read the MSDS sheets for chemicals before using them, always wear appropriate personal protective equipment when handling chemicals, and always keep solvents away from open flames, sparks, and other possible ignition sources!
Personally, when pouring chemicals I just wear safety glasses and make sure to have adequate ventilation. If you have super sensitive skin then use latex or viton gloves are resisn(not nitrile or PVC).
Despite what is commonly repeated, acetone (and isoproptyl alcohol for that matter) is actually a fairly safe chemical as far as human exposure is concerned. Though it doesn’t smell good, you would have to be exposed to a lot to actually be harmed. It is just an irritant in low concentrations, all the bad stuff happens at high concentration levels. Acetone is not regarded as a carcinogen, a mutagenic chemical, nor a concern for chronic neurotoxicity effects.
The device in this instructable uses materials which enable the safe indoor use of acetone for polishing ABS or isopropyl alcohol for polishing 'PolySmooth' material. Specifically, the tubes are EPDM rubber and latex rubber. All clear containers used are polypropylene. Please do not mix chemicals or use different chemicals than I've recommended without doing appropriate research first!