In our test we printed two copies of the same object. Then we placed them in 8oz containers with water and let them dissolve for an hour. One was being agitated while the other sat stationary. After dissolving for an hour, the stationary print still had significant amounts of support material on the part.!
The motor speed can be tuned to get the part spinning, producing more agitation. Full power of the motor is a bit too intense and may unbalance the load which could get messy. Admittedly there's more testing to be done, agitator parts certainly seams to dissolve PVA material much faster than stationary bathing.
The container with the stationary part left behind a goopy mess. The PVA settles to the bottom of the jar and collectively becomes a sort of jello. It wasn't easily removal from the container as it becomes thick and sticky. However, the container with the agitated part did not have this PVA jello. The material dissolved into the water.
In our previous testing, we simply left parts in water over night, well over 8+ hours. Even still, tiny bits of PVA still remained on those parts. Agitating the part seams to break apart the PVA and better dissolves the material.
In our test, agitating PVA parts certainly speeds up the post-processing compared to non-agitated parts. The container used in this project is an 8oz jar with an outer diameter of 72mm (2.8in). This will only house parts that can fit within that volume. For agitating bigger parts, a new custom holder can be made to fit a larger container. The rotating tray measures out to 118mm x 92mm (4.6in x 3.6in) so it can support objects within that build space.
This model of a hilbert cube on thingiverse is a great demonstration print that we used to test our agitator. It also fitted nicely in our 8oz container. The hilbert cube is a cuboid with intertwining pipes and intricate overhanging geometry – Perfect for 3D printing with PVA support material. Credits and sources can be found in the thingiverse page. So how did we slice this thing anyway?
Slicing Hilbert Cube
We sliced the STL model using Ultimaker's CURA 3.x. The part was 3D printed using an Ultimaker 3 with a stock AA 0.4mm PrintCore for PLA and a BB 0.4mm PrintCore for PVA. With this combo the nozzle loaded with PVA is set to print only the support material. The supports are automatically generated in CURA using the slice settings listed below. For more info on 3D printing PVA, check our out D20 guide.
The settings below are for Ultimaker CURA 3.x using a PVA profile with 0.4mm BB printcore. Use a prime tower and increase the thickness and flow to create better quality support structures. Lower the retraction count will minimize grinding of the material.