A bit of background

A project log for Oasis 3DP

A powder and inkjet 3D printer based on HP45 inkjet technology

Yvo de HaasYvo de Haas 03/13/2018 at 20:050 Comments

This project did not come out of nowhere. There have been several projects leading up to Oasis. Before I start narrowing down the details of this project, I want to give a quick summary of the projects leading up to this one.

TL;DR: 3 printers and 3 inkjet controllers, just watch the videos.


Focus was made 2012-2013. It was made to answer the question how hard SLS can be. It was a poorly researched question at the time, and I was not yet an experienced engineer, but I wanted to try anyway. Focus was designed to be a simple and cheap laser platform. It had a Ramps2560 at it's core. While it was both cheap and simple, it was unreliable and completely failed to do any laser sintering. The pistons wobbled, leaked powder and jammed after an hour of printing. Sintering required way more hardware than Focus had.

Not to let Focus go to waste, I decided to modify it to powder and inkjet (3DP). It requires roughly the same hardware, and the C6602A was already hacked and known about, due to the open source Inkshield project. The C6602A has 12 nozzles at 96DPI. Focus itself did not support real inkjet in the firmware, but the C6602A was hacked so that a single nozzle could trigger repeatedly, based on an external pin.

It was not fast (a new layer took 30 seconds) or precise, but Focus successfully proved that powder and inkjet was a viable technique. Based on the knowledge of Focus, I built a new powder printer.

(The video is printing on paper, there never were good videos of printing in powder, and this shows how it worked better)

Plan B

Plan B was a response to Focus, fixing all problems Focus had. It was to be faster, more reliable and capable of real inkjet, not just a hacked inkjet head. Initially the controller was a Megatronics V3 (an Arduino Mega based controller). Reliability was indeed a lot better. Plan B could print a lot longer without jamming. To get it to be faster, the complete powder handling hardware was optimized for speed. This meant an odd 2 feed hopper system and a separately driven spreader. A new layer could be dispensed in under 10 seconds.

Plan B fulfilled every goal. It was a LOT faster, and rarely jammed. The firmware was specifically designed for inkjet. The printing speed was around 50mm/s, the fastest the firmware could handle before skipping functions. The software side never really worked reliably, but it did all it needed to do for me. There were problems though. The frame was made of lasered aluminium, something I had easy access to at the time, but is difficult for others. The gantry was designed for speed, but did not allow for any upgrade. Later upgrades were really difficult to implement.

The controller was later upgraded to an Arduino DUE to increase printing speed to 150mm/s, but Plan B was then stopped to give me resources for a new printer. The C6602A printhead was fine for hobby projects, but not for powder and inkjet printers, and I had a lead on a better printhead.

HP45 controllers

I started working on the HP45. Several meetings and some patent digging gave me enough confidence to start working on it. The HP45 has 300 nozzles at 600DPI. There was quite a bit of mistakes that I will not go in to now, but slowly but surely I got more control over the HP45.

Several controllers were made, mostly based on the Teensy family. Initial controllers used huge arrays of pogo pins to connect to the 52 contacts on the HP45, later I got a big batch of the original connectors. Most controllers had massive feature creep and quickly grew to a size that I had difficulty managing.

Oasis prototype

Somewhere in this development, the first version of Oasis was built. It was designed around a Teensy 3.6 as the main controller, handling both motion and inkjet. It printed from SD card using Slic3r SVG files that it parsed on board.

This prototype is the best thing I made so far. The Teensy 3.6 was at its limit decoding, handling motion, and inkjet. The Oasis prototype was wonky and I did not allow for much more than it shows here. I wanted something that was a bit more future proof. In future logs I will share the idea on how I want to make the real Oasis.