December 12, 2013

Three-Dimensional Shenanigans

So I purchased a 3D-printer from PrintrBot this past Black Friday as it was something that has been on my list. For the past several days, I've either been assembling it or tweaking it to optimize printing. In that short timespan, I've come to learn a good deal about 3D-printing as well as encountering some of the common mistakes and errors. I want to create this post as both a reference for myself as well as anyone else who may be starting out and run into the same issues I have.

To begin, I purchased the PrintrBot Simple Kit both because of it's low cost and I felt like bulding something fairly challenging. Assembly was a breeze with the lazer cut wood and fairly thorough set of instructions provided on their website. More interestingly though were the issues encountered during printing.
After getting the printer to what I thought was at least half calibrated, I tried my my first print. With no software modifications beyond what are the recommended defaults from Printrbot, my initial print turned out as such:

Calibration Cube 1

Clearly this looks nothing like the advertised model. As you can see from the image, the top layers of plastic were not sticking to the bottom, thus the web-type effect between cubes. When the print head moved from one cube to the other, the extruded plastic would follow it and then attach where it wasn't supposed to.
Some possible reasons:

1) Unlevel Printbed
Initially I just took a level to the print bed and tried my best to ensure that it was level with respect to the surface it was sitting on. This turned out to not be enough. In order to adequatley level the bed, my method was to lower the Z-axis until it hit the bed (barely hit it) and then modified my Z-axis stop so that at that point it would stop. I then moved the extruder head up and down the X-axis as well as the Y-axis visually inspecting the extruder nozzle to make sure it stayed the same distance from the bed, adjusting along the way. There is a great blog series here on calibrating the machine and what all the terms mean.

2) Uncalibrated Z-axis Motor
I touched on this above, but if during the print, the Z-axis motor is not a uniform distance from the printbed, then the current layer of plastic will not correctly contact the previous plastic layer. Again, visually inspect that the extruder nozzle is a uniform distance from the printbed at various X and Y coordinates.

3) Software
Software can cause all sorts of problems if out-of-date or not properly configured. My current software stack for 3D-printing with the Simple is Repetier for connecting to the printer and Slic3r for generating the G-code. Look for a later post on my ideal settings for both programs as I am still playing around with them. In short, making sure that all this software is up-to-date can do wonders for your prints as I will show in the next two prints.

After making some tweaks to my setup, I was able to print out the following two models:

Calibration Cube 2

Calibration Cube 3

Between the second print and the third print, all I did was update to the latest version of Slic3r and generated the Gcode separate from Repetier. I also increased the infill from 40% to ~60% (this was when I actually learned what infill was). Print quality increased drastically as shown.

Future posts:

  • Slic3r Configuration
  • Gcode Manipulation