May 11, 2015

How to make DIY ultrasonic vapor polisher for 3D printed objects

Micheal, well known for his TestrBot made another useful and easy DIY project that enables you to build ultrasonic vapor polisher for your 3d printed objects.






























Here is the project summary:

What's needed is a better solvent application method, and that's what this Instructable is about.
The current vapor polishing methods and their drawbacks include:
  1. Hot treat via boiling solvent in a crock pot or similar chamber (Potentially dangerous and very hands-on process)
  2. Cold treat via slow release of solvent from paper towels in an enclosed container (Very time consuming, can't observe parts during this process.)
  3. Spray canned solvent aerosol onto part. (Inconsistent surface finish, must be done outside)
  4. Dipping parts directly into liquid solvents (Unpredictable/inconsistent finish, Likely over exposure of part)
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. I'm also forgetful so I don't want my parts to be destroyed if I forget that I left them in the machine.
The Ultrasonic Misting 3D Vapor Polisher is the solution to all of these problems.
This key component of this machine comes from ultrasonic humidifier, which 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.
This fog mist is very dense and wont move far on its own, so I used an aquarium air pump to blow it from the misting chamber into the glass finishing chamber where it can condense on the 3D printed part. This airflow keeps the air moving inside the finishing chamber, which helps produce a consistent finish on the part. The airflow system is open by necessity but we do not want the exhaust air to become a fume hazard so there is a water bubbler on the exhaust to absorb excess solvent. (Note that this only protects you when using water miscible solvents such as acetone.)

Here is the video of machine in action and results of the treatment:



Detailed build guide can be found here:

http://www.instructables.com/id/Ultrasonic-Misting-3D-Printing-Vapor-Polisher/

Here are results of strength tests with lots of charts:

http://www.instructables.com/files/orig/FQQ/HMAJ/I98BK9P2/FQQHMAJI98BK9P2.pdf

Conclusion was:
The vapor treatment resulted in a consistent overall weakening of the test specimens. Specimens that had not been treated with Acetone vapor had an average yield stress 24% higher than those treated with the vapor.
Solvents that can be used to polish different materials:
  • ABS: Acetone
  • Acrylic: Most Solvents
  • PLA: MEK or 'MEK Substitute'
  • PVA: Water
  • PVC: Most Solvents
  • Polycarbinate: Pretty solvent resistant
  • Nylon: Pretty solvent resistant
  • Polypropylene: Pretty solvent resistant
  • Polyethylene: Pretty solvent resistant

Stay safe people! Chemicals are dangerous! You can check this chart showing dangerous combinations:

http://www.safety.vanderbilt.edu/chem/chem-compatibility-chart.pdf

Update (26.09.2016.):

Here is the upgraded PRO version of this vapor polisher made from simple plastic boxes:



Detailed construction guide can be found at:

http://www.instructables.com/id/Automated-Ultrasonic-Misting-3D-Print-Polisher-PRO/