I 3D printed some parts to mount everything in a fixed position. The part that holds the nozzle can be rotated in the X and Y axis to aim the ink stream at the copper tube.

For now, the printhead contains a 0.1mm nozzle with a check valve to prevent ink from leaking out when not pressurized, two piezo rings, a LED in a sealed tube to protect it from ink, and the ink return line.

The start of the return line is made of copper so that it can be later used for detecting charged ink drops.

A charging electrode and a high voltage deflecting electrode are missing at the moment because I first have to get the ink stream splitting right before I can go to the charging and deflecting.

Here you can see a first test of the ink stream splitting. While it's not working as intended, yet, you can see the ink stream splitting just before entering the tube.

At the first glance there are two problems:

One is a "shifting" of the ink stream when the timer pipe gets loaded with new ink. The normal pressure of the timer is 40 psi and it gets loaded with 60 psi so that loading does not take too long. The problem is that while loading the pressure in the timer rises to around 50 psi until loading is finished. Because of that, the position of illuminated droplets changes with the increasing and later decreasing ink stream speed. I guess like said in a previous build log, that this behavior will likely cause problems at some point. Maybe a better pressure regulator could solve this problem 🤔. I will ask a pneumatics hardware dealer or some expert about this...

The other one is the "late" splitting of the ink stream - I want the ink stream to split as early as possible after exiting the nozzle.

For this test, I used the two piezo rings from an ultrasonic transducer which are rated for 60W 40kHz. I read before that the optimal frequency for ink stream splitting should be around 64kHz. I tried 64kHz with the piezo rings but with seemingly no effect and so I tried 40kHz and got the result that you can see in the photo - which is something, but not the result I'm looking for.