I searched for “3D printing” in the forums, and it seems that topic hasn’t been touched.
So, just to share some experiences…
Motivation:
COVID-19 lockdown. 
I like to repair stuff, and sometimes it’s impossible to get something you need. So, I decided to look at 3D printing.
Hardware:
I bought an Anycubic i3 Mega S. My thoughts: solid hardware, the firmware is junk. This review sums it up: Anycubic i3 Mega S Review
There are essentially two printing methods out there (there are more, but realistically for our wallets just 2):
• Fused Deposition Modeling (FDM): printing with a melted/extruded filament through a heated nozzle.
- Digital Light Processing (DLP): creating layers with a photosensitive (UV) resin
I you are looking for the best quality (model making, figures, complex shapes) go for DLP. For less complex objects, “real life usage”, go for FDM. I went for FDM.
If you are looking got a (used) printer, consider the following:
- A heated bed is a must. Reason: if the printed object is heated from below while printing, there will be fewer temperature differences, less warp, less separation, less hassle. My verdict: never by a 3D printer without a heated bed
- 1,75mm filament is standard. If you see a printer that uses another diameter, skip it
- firmware/software/WiFi: don’t worry, see below
- a 0,4mm nozzle is standard and a good starting point for beginners. Stick to that.
Setup:
- setting up the printer is pretty straightforward. Difficulty level: easy IKEA desk
- feeding filament into the printer: easy
- VERY IMPORTANT: leveling the printing base/adjusting Z-axis. In this step, you make sure the bed is level to the nozzle across the whole area. Take your time doing this, and it’s better to repeat 2-3 times when learning how to do it. Don’t get intimidated; it’s pretty easy. For my printer: go into the menu ("Tools->“Home”->“Home Z”), move the print head to one of the corners, and slip a thin paper (supermarket receipt) between the nozzle and the bed. Adjust distance (screw under the corner) until you can still move the paper with some friction. The paper should not be stuck between the nozzle and bed. But also not move freely. Repeat for all four corners and the middle. Tons of YouTube-Videos showing that process. Again: VERY IMPORTANT!
First print:
- use PLA filament. There are various materials out there. PLA is the easiest to print with.
- my printer came with an SD card with an example on it. Insert card, feed filament, select print in the menu. Watch the first layer being printed. It should print cleanly. If you have problems here: look at leveling.
Next print:
- I looked at some examples at Thingiverse
- My goals: get a feel for the software I could use, what to expect from the printer
- Discover potential pitfalls
After several prints, I came to the following conclusions and improvements:
- STL is the standard file format for printing. It is NOT a CAD file, but already an export from CAD. So if you download objects from the web, 99% of the time, you are getting STLs.
- The STL needs to be “sliced” (think CAM). You need an application that converts the STL into G-Code, which is the language your printer understands. The Slicer considers the characteristics of your printer (max. print size), the material used (temperatures), and other parameters.
- I tested:
- CURA: everybody is using CURA. Like: lots of features. Dislike: only uses one core when slicing. It can be slow.
- Slic3r: I didn’t like the UX.
- Later, I found: PrusaSlicer, a fork of Slic3er by the manufacturer of Prusa printer. But: works not only with Prusa printers but with every other printer
- Now I am just using PrusaSlicer. I find it performs way better than CURA
- Biggest (potential) pitfalls: bed adhesion is very important (check leveling, clean the bed, for some materials: cover the bed with 3M tape), be aware of your settings (different filaments: different temperatures for nozzle and bed, speed may vary). Recommendation: stick the PLA at the beginning. ABS is way more problematic (bed heating, adhesion, warping). I had some trouble with PETG prints, but the error was mine: low printing temperature.
Now the big one:
- I started to hate the fact that after slicing, I had to export the G-Code to an SD card, walk to the printer, insert the card, press menus,…
- there are printers with (W)LAN out there, but they cost significantly more
- the solution: OctoPrint. https://octoprint.org A “web interface for your printer.” You attach the printer to a computer, and it controls the printer, bypassing all the menus.
- I don’t have computers to spare, so I bought a Raspberry Pi. Not the newest one, the 4, but the older 3B, so I saved money. OctoPrint for the Raspberry is called OctoPi GitHub - guysoft/OctoPi: Scripts to build OctoPi, a Raspberry PI distro for controlling 3D printers over the web
- Installing OctoPi: using Raspberry Pi Imager, it’s straightforward (Control+Shift+Y to set up WiFi).
- With the Raspberry connected to my printer: no SD cards anymore. The printer is accessible from my MBP via browser. PrusaSlicer and CURA can print directly to OctoPi.
- Recommended plugins for OctoPi: ArcWelder (G-Code command conversions for better printing), Dashboard, Filament Manager (keep track of your filaments), Firmware Updater, PrintTimeGenius
Now I had the printer set up, learned some stuff about printing, had a smooth workflow for printing.
What if you want to design your parts?
Difficult to answer since many roads lead to a printable design. It depends on what you want to do.
- Google SketchUp: probably the easiest way to get quick results.
- Blender: if you want forms, think “3D drawing or art.”
- FreeCAD: full CAD suite, if you care about technical stuff
- Fusion 360: as FreeCAD
I went the Fusion 360 route. FreeCAD has a steeper learning curve. Fusion is free for “makers.” Since I don’t want to rely on this being available forever for free, I am investing some time in FreeCAD. Both are parametric CAD programs, meaning you can design parts with exact measurements, angles, diameters, etc.
- have to research this some more