In case you missed it, this is a continuation from Adventures in 3D Printing – Part 1.
The next step in the printing process it to take the 3D object file and “slice” it. A slicer is program that creates the layers that your 3D printer will print. There are multiple programs that will do this with some adapted to specific brands of printers. The slicer and its settings are quite important. Your 3D printer is a dumb device. The printing logic and working around any limitations in your printer is done in the slicing software.
I use Ultimaker Cura. Miracle of miracles, it’s both good and open source. The problem is that the learning curve is rather steep. You’ve got a ton of options. When you first start printing and your prints first start failing you are going to be completely confused. You will be unsure if the issue is your slicer settings are incorrect or if you printer is incorrectly set up. Or, sadly, it can be a combination of both issues. Honestly, it took me 40 hours or more to get good consistent prints. The way to help avoid this is buy both a printer and slicer that is integrated by the manufacturer. One such example of this would be Prusa. You will pay for this, but for many it may be worth it.
Below we just imported our STL file into Cura. You’ll note that it’s huge with a diameter of almost 100mm.
Rather than permanently lose resolution by shrinking this in the CAD program, it’s better to let the slicer scale the object. Here we will reduce the x and y size to 35% and reduce the height to just 10% of the original size.
I’m also printing this with a 0.12mm layer height. Right now, I’ve got a 4mm nozzle on the printer and that is the smallest layer height I can print. More expensive printers will have multiple print heads with multiple nozzles. I tend to print functional parts so 4mm is my usual nozzle size. I also have larger nozzle sizes for even bigger parts. If you do more fine and artistic objects you will want to use smaller nozzles. Naturally, a smaller nozzle means longer print times. The quality of your printer will determine the minimum and maximum nozzle size you can use.
You also control the space inside the object you are printing. 3D printing is additive so you need to tell the slicer how much plastic you want to use inside the object. For decorative and light duty parts you can save yourself a lot of print time and material by selecting an infill of 15% to 40%. For structural parts you use something like 60% to 100%. For something small like this 20% is perfectly fine. However, because this object is so small there will be very little infill.
Depending on what kind of plastic you are using to create the object you will need create and change settings as well.
The primary materials used in basic home 3D printing are PLA, PETG and ABS. I won’t go into too much detail here as there are plenty of other resources if you are interested. PLA is the most forgiving (and generally best looking) plastic used in 3D printing. The problem is that other materials are stronger, it degrades with water exposure and it can warp in direct sunlight. It’s fine for decorative items and most structural things used inside, however. ABS is stronger and UV and water resistant, but much harder to print and it stinks. PETG has most of the properties of ABS, but is easier to print and doesn’t stink. I use it for most structural parts. For other stuff I use PLA.
In this case I’ve PETG loaded into my 3D printer and I’m too lazy to change the spool of plastic. So these are the temperature settings for both the molten plastic and the base of the printer that I use to print PETG.
After that hot material is extruded from the printer it needs to be cooled. Again, this takes some trial and error and practice . It will depend on the material you are using, the brand of that material and your printer.
Finally it’s time to “slice” the object!
The slicer will display each of the layers that will be printed. In this case the whole object is going to be created with 8 layers, has an estimated print time of 11 minutes, and since I’ve inputted my material costs into the slicer it estimates it will use 19g of plastic at a cost of about $0.01.
Below is what the first layer is going to look like. The border around the object is known as a “skirt” and is there to get the plastic properly flowing and up to temperature. It is essentially scrap that is part of the printing process.
In the image above you’ll note it says “Print with OctoPrint”. My PC is in my home office on the second floor of my house while my printer is in the basement. Normally the only way to get the output from your slicer to the 3D printer is put the file on an SD card and in turn put that SD card into the printer. It’s the 2000’s version of the floppy disk shuffle. I got tired of going up and down three flights of steps every time I need to print something. This is particularly painful when you are first learning because you may likely have to modify your slicer settings multiple times after your print keeps failing to print.
My (and many others’) solution to avoiding the SD shuffle is a nifty little piece of software called OctoPrint. This is a custom Linux distribution that runs on a Raspberry Pi. So for roughly $50 and probably another 25 hours of your time you can turn your 3D printer into a network attached device. There also many add ons that make printing easier and more powerful that are built into OctoPrint. One such feature remote monitoring and remote operation. This make the fact that you are going to have to deal with Linux worth the price. My recommendation is to get your printer and slicing skills in order first, before you try to start using OctoPrint.
In the slicer we simply click the button and send the file directly to the Pi. In turn, the Pi will stream the file by USB directly into the printer. In Part 3 I’ll show you what my printer looks like, its modifications, and we will finally print the object.
The picture below is a sample (from the OctoPrint web site) of the web page you use to access OctoPrint web.