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Writer's pictureJD Wallace

My 3D Printing Lab

Updated: Jan 1, 2021

In around 2014 I discovered 3D printing and had a ton of fun with the hobby. I recently came back to it after a few years of inactivity. A lot has changed and I'm still working to catch up, but wanted to document what I have learned so far. I'm sure there are plenty of new tools I've not even discovered yet; and I'll continue to experiment as I learn more, but for now I'm pretty satisfied with this setup.


Printer

Printrbot Simple Metal (1403) w/ Heated XL Bed Upgrade

  • A 2014 design, built like a tank. Discontinued and no longer supported, but still a wonderful machine. With new high quality printers still going for $1,000 or more; it's great to be able to continue to enjoy the hobby with this 6 year old printer. The Printrbot is a typical fused filament fabrication (FFF) style printer.


  • An 8 bit microcontroller board that shipped with the bed upgrade. This controller receives input from the thermistors, end-stops, and bed probe; provides power to the extruder and bed heaters; and drives the stepper motors that position the nozzle and extrudes the filament.


Firmware

  • The Printrbot's Printrboard originally shipped with a customized fork of Marlin 1.0 firmware. I've discovered the latest build of Marlin 2.0 not only works great, it's a serious enhancement in capability over the original; breathing new life into this older printer. It does require a bit of work to get this firmware installed, but I've written a tutorial here. The Marlin firmware is responsible for accepting g-code print commands and translating them into the right combination of coordinated hardware commands that will result in a clean print.

Controller

  • The Printrboard built into the Printrbot is fully capable of driving all of the necessary hardware, and can even manage its own print jobs from g-code files loaded into the on-board microSD card reader. It's far more convenient however to have a more powerful computer managing higher level functions like job management and remote access. I could dedicate a traditional PC to this task; but OctoPrint running on a small Raspberry Pi offers a lot of features in a tiny package. The Raspberry Pi 4 8GB model might even be overkill for the job; but at only $75 it's an easy investment and ensures I'll have plenty of power to install any of the more than 250 plug-ins available for OctoPrint.

  • If you're looking for a more economical option, the RPi 4 2GB model is only $35 and OctoPrint will also run on any RPi 3B or newer you happen to have lying around.


Slicer

  • Most 3D models used in 3D printing are saved as STL files. These files describe the shape of the object, but lack any of the necessary detail to tell a printer how to print them. Software called a "slicer" is used to translate these STL files into g-code commands the fused filament fabrication printer can understand. In effect, it "slices" the model into layers and plots a linear path for the printer nozzle to follow in order to build each layer out of the extruded material. 3D models could be shared in raw g-code format, but since each 3D-printer could have a unique combination of capabilities, filament parameters, and print preferences; it makes far more sense to custom slice each model.

  • PrusaSlicer is a fork of the Slic3r project which is developed and optimized for the Prusa3D brand of printers. PrusaSlicer seems to have developed at a faster pace than the original Slic3r code it was forked from; likely due to the financial support afforded to it by Prusa Research. Despite being optimized for their own printers, I find it still works very well for my Printrbot.

Other Upgrades

  • The heated bed upgrade for my Printrbot originally shipped with a piece of Kapton tape to be applied to the print surface (it's the orange material in the first photo above). The Kapton was a big improvement over the blue painter's tape I had previously been using to help with print adhesion, however over time it had become scratched and damaged in a few places and needed to be replaced.

  • While researching a replacement for my damaged Kapton tape, I came across several references to a material called PEI that had gained in popularity as a print surface. I was able to find a sheet large enough to cover my entire print bed with adhesive pre-attached for only $14. I've only tried a few prints with it so far, but the results look pretty good.

  • A note on installation. I found several cheaper offerings for PEI sheets, but upon closer investigation realized they did not include adhesive. I could have purchased and installed adhesive on my own; but for $14 it was worth it to me to not have to worry about getting the lamination right. I also found it incredibly easy to cut the sheet to the proper size. I used a rotary paper trimmer first and then once the sheet was installed I used an x-acto knife to clean up the edge. The slightly more rigid nature of the PEI as compared to Kapton make it very easy to install without trapping any air bubbles.


  • My Printrbot was an earlier model that shipped with the Ubis 13 (a.k.a. Ubis Ceramic) hot end. The Ubis 13S is a compatible but improved version that is still be available, but you'll need to add a cooling fan which I've documented in this post.


Z-Axis Conversion

  • The Printrbot Simple Metal includes one proprietary consumable part that will eventually fail. The delrin z-nut that is threaded onto the 5mm z-axis screw will start to wear out over time and cause wobble or even worse, failure of travel in the z-axis. There is no longer a source for the original replacement part, but I do have a couple of options.

  • I can of course just print a replacement, and in fact I have done just that and stashed it in my spare parts bin just as a backup; however I'm not confident the tolerances would be precise enough to actually work.

  • The better solution, and the one I'm currently working to implement is to completely replace the z-axis screw with one that has a machined nut that will stand up to wear longer and presumably result in more stability for z-axis movements. This process has been documented by others here, and here. I'll document my own upgrade in another post once the parts have arrived.

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