In designing and building my own 3D printer, I went through a series of decisions that lead me to the final printer. I made some sacrifices, and they lead to unexpected interesting traits for the printer that haven’t been seen or documented prior (to my knowledge anyways). Thus, I am revising my original design into a Core X-Y design to allow for faster printing and travel movements, much faster acceleration and shorter bowden tubing. Additionally, with such a large print bed, it is very annoying accurately leveling (or tramming) the print bed, and I would like to address this issue. Other smaller problems are the oozing problem with 2 separate extruder nozzles on the printer, and so, I will make my own mixing extruder. At the moment, I am printing off the new parts for the printer, so stay tuned for progress updates.

My original goal for the EasyBake was to have as large a printer as possible built for as little money as possible. Because of this, I did not use lead screws, and minimized the number of vertical elements that I would need. However, this lead to a combination of interesting properties that ultimately made me decide to rebuild the printer. The main problem is two fold:

1. The carriage that moves in the Y direction is very large, and therefore cannot accelerate quickly
2. The bowden tube ended up very long, reaching from the top edge of the printer to the furthest corner

This combination of qualities lead to the printer encountering an interesting problem: it can never extrude the correct amount of plastic. This is because the acceleration settings have to be extremely low to accommodate the large mass of the Y carriage. This combined with the spring-like quality of bowden extruders meant that at the edges of a part, when the print head changed direction, the spring tension would be relieved and extra plastic would ooze out. This over extrusion only occurred at the change of direction, meaning that the rest of the extrusion path – all throughout the center of the part was under extruding. Thus, the printer could both over extrude, and under extrude at the same time, making small parts come out decently, but larger parts with flat surfaces were a real problem.

The problem became most apparent when doing large flat prints for a project, when the extrusions would tend to peel up in the center of the print, as though there was no layer adhesion, or it was under extruding. The photos below show examples of this.

So, redesigning the printer to avoid slow acceleration times and use shorter boden tubes meant converting to a Core X-Y design, and mounting the feeders closer to the hot end of the extruder. Thus, taking the Y carriage, and turning it into a Z carriage instead would allow re-using existing parts and hardware, while also allowing mounting locations for the extruders to be much closer to the hot ends. The SolidWorks model of this design can be seen below.

Above: The original EasyBake with a large Y-carriage

Below: The new Core X-Y EasyBake with a Z-carriage

A closeup of the Core X-Y