Introduction
So, you are thinking about getting a 3D printer, or you have just got a 3D printer and are ready to start printing out tabletop stuff! Good for you, it’s a lot of fun. This article is going to focus on FDM printing (plastic filament). In my opinion, this is good for printing terrain and larger vehicles - I don’t think this tech will ever be good enough to print minis. For that, you want a DLP printer, which is a whole other artlcle. I am going to focus on the I3 Mega by Anycubic because it’s an excellent, inexpensive, and easy to use printer, but some of these tips will apply to any kind of FDM printer. Most of them are pretty much the same but with different features added or removed.
What to look for in a 3D printer
Before you get into printing, you have to have the mindset that this is a platform, not an appliance. If something breaks, you’re going to be replacing a part, not the printer - and there aren’t any parts on the printer that really will cost more than $30USD tops. It’s possible for the thermisters to fail on the hot bed and on the hot end, and so on. I’m not saying they’re unreliable - i’ve run mine for over a year almost nonstop with only replacing a few small parts - but making sure you get one with a tinkerer’s mindset in mind. If you have ever done basic repairs around the house or built your own PC, you have all the experience you need. Tools you will want are a set of hex keys, some small wrenches, and tweezers. Calipers are nice but a ruler will do as well. For removing supports, I like to use a pair of heavy hobby snips (cheap and crude is best, you don't want your fine Xuron flush cutters for this) and a pair of needle nose pliers.
Ideally you will have full metal frame with a base size of at least 200x200x200mm. The larger the base, the larger kinds of prints you can do. You also 100% want a heated bed - I wouldn’t buy any printer without one. This is essential for printing many different materials. Some newer printers have a flexible metal plate that lays atop the heated bed, and those are truly excellent as well. I personally like it when the filament spool is not physically attached to the printer - I don’t like the vibration introduced by the shaking of the spool, but this is just me.
Initial setup & software
The first thing to do is check every exterior screw to make sure it’s tightened. You’d be surprised how many show up with critical structural screws only halfway tightened - but it’s traveled thousands of miles.
I would suggest calibrating your extruder. To do this, I would recommend downloading MatterControl (free) and following this tutorial https://www.matterhackers.com/articles/how-to-calibrate-your-extruder
It takes a few minutes but is totally worth it.
Once the extruder is calibrated (you only ever need to do this once unless you change the extruder), you will want to level the bed.
Adjust he bed screws so it's in the lowest position - you want to raise the height, because if it's too high, the nozzle will crash into the bed and possibly scrape it up.
Take a piece of paper (the I3 Mega comes with one for this purpose) and put it on the bed. Start pre-heating the bed to 60C. While you are waiting for the bed to heat up, home the head and then turn off the motors - this allows you to freely move things. Measure the distance between both the left and right sides of the arm that carries the hot end - are they exactly the same height? If not, turn the lead screw on the higher side until they are the exact same height. Once the bed is heated to 60C, put the paper on the bed, and slide the nozzle over the corner of the paper. start tightening the wheels until there is some resistance on the paper - you should be able to pull the paper from under, but not easily push it. You want some resistance but not too much. Do each corner, and then the center - they all should have about as much resistance.
Once done, print some calibration squares and make sure they look right. Adjust as needed. I like these calibration squares: https://www.thingiverse.com/thing:3678581
Leveling the bed is a little tricky and takes a while until you know how it should feel, but once it's done it stays leveled for a long time.
Slicing, STLs, and where to find them
To actually print 3D files, there are 2 steps. First, you need to get a model - typically in the STL format. There are plenty of sites to get STLs from:
Thingiverse - has about a bajillion models. Free.
MyMiniFactory - another great site for finding files. Some are free, some cost money.
Gambody - this is a pay site that sells decent quality models. There are sometimes free alternatives on Thingiverse, but the paid ones are usually a little more detailed.
Once you acquire your STL file, you need to slice it - you can't print a STL file directly. There are many different software applications you can use, but Cura is free, very easy to use and I would recommend it. You can orient and rescale models in Cura, and output gcode, which is what the printer actually uses to print the mode. See the Cura settings section for ideal printer settings.
Different filaments
There are many different, exotic types of filament available to print with. With the tabletop environment in mind, I would recommend regular old PLA. This is easy to use, forgiving in required temps, and very cheap. The other common ones are PLA+, which costs a little more but is a little stronger - you likely don’t need the strength for tabletop wargames. ABS is used for functional parts - it’s very strong. The downsides of ABS are that it smells awful when printing, and warps very easily when hot. You will need an enclosure of some time to keep the temperature stable when printing ABS - a cardboard box is adequate.
Hardware tweaks
There is one fatal issue with the I3 Mega that needs to be remediated as soon as possible - the wiring for the heated bed is cable tied to one corner of it. This means that as the bed travels back and forth, it’s constantly flexing at that one point, and will cause the wiring to eventually fray inside. At best, this will cause the heated bed to fail, and at worst it can cause a fire as the current is being carried inside just a few strands of copper. This isn’t hypothetical, this is a thing that will actually happened and my own heated bed’s wiring melted.
To fix this, you need to install a drag chain. There are 2 elements to this - adapters that you can print for free off of Thingiverse, and the actual drag chain which you buy off of Amazon or elsewhere.
The adapters are here: https://www.thingiverse.com/thing:2979867
The drag chain is here: https://www.amazon.com/gp/product/B07BM7D45Q
Cura settings
There are a billion different settings in Cura and I can’t list them all. However, I am going to touch on some of the important ones:
For larger rough terrain (rocks, bases) printing at 0.2 is adequate.
For finer details (vehicles) you will want 0.1
I usually do infill 15%, grid
200c for PLA
Retract 8mm
Print speed 45, wall speed 22.5, initial layer 22.5
Travel - combing - not in skin
Support - everywhere, zig-zag, support z distance .2
Uncheck enable support roof
Use towers
Adhesion - skirt (use brim if it’s something really topheavy)
Experimental - break up support in chunks, enable coasting
Troubleshooting
They sell kits, accupuncture needles, that you can use to clear clogs inside the nozzle. The nozzles are 40 cents or less each. I ordered 10x from Aliexpress and just remove and throw out the nozzle if it clogs; I don’t have time to mess with that.
Most people bypass the broken filament sensor. You get smoother filament feeding without it, but you also can’t resume a print if you run out of filament. Once I get to the 25% or less part of a spool and am about to start a large print, I will thread it through. I have definitely been able to successfully resume prints where I have run out of filament so it does work.