If you have turned on the TV or gone online once in the last five years, you have no doubt heard about 3D printing. It is the new tech fad that has swept the world and it makes a lot of promises. Need a new pair of shoes? Print them! Need a new liver? Duh! Print it! Need a space rocket engine? Why do you even have to ask?!...PRINT IT!
On the surface, it sounds amazing and granted, it is a fairly fantastic technology. In the right hands, it can be used to make objects that could not be made with any other manufacturing technique. This opens us up to a whole world of things almost unimaginable otherwise. Unfortunately, it is not quite as great as it sounds when it comes to consumer 3D printing.
Consumer-grade 3D printers suffer from a long line of issues that will put nearly all of the fantastical promises outside our grasps. I don't want to discourage you to buy or build a 3D printer as they are a fantastic hobby and one I enjoy much myself. BUT, you should be aware of the limitations before you drop a grand or two on Kickstarter, Ebay, or one of the many established companies.
First up, 3D printers are not and will likely never be low maintenance machines. While certain models and modifications need less than others, they do require regular maintenance.
#The heated nozzle that melts the plastic will become jammed at some point which means taking apart the assembly and removing debris.
#The print bed, where the 3D print is stuck to, will need to be degreased with acetone and the surface replaced after wear fairly often.
#The rails, rods, bearings, and brushings (aka moving parts) need to be lubricated just like your car does. Cheaper moving parts that haven't been hardened or made of engineered materials will need to be replaced when they pit or grind.
#Over time, the printer will fall out of alignment and will need to be recalibrated
Second, 3D printers are not particularly reliable. Again, nicer models and modifications can help ease this, but if you buy/make a printer expecting it to be perfect every time, you may need to reevaluate your decision.
#Heated plastic expands and contracts which can lead to cracks, warping, and a whole host of nasty things that can ruin your print. Most of these defects only appear far after you've past the bad layers and the plastic has cooled.
#Jams in the heated nozzle or in the extruder that pushes the plastic into the nozzle will jam which will ruin your print if not caught instantly. This is one of the more common failures. Chances are, you won't be staring at your printer for the duration of a 4+ hour print, so catching this is hard.
#Prints can decide not to stick to the print bed. There are a million theories on what the best print bed material and preparations are but none are perfect. If your print dislodges from the print bed, your print is done for.
#Some printers use a fuse-like electrical component called a "poly-fuse" that is designed to act like a fuse in the event of a short circuit but will start working again after a power reset. These are great, but they can heat up and falsely trip which means no power to heat your printing nozzle, move motors, ect.
#While the open source software running most printers is usually stellar, it can sometimes have bugs that ruin your print. It is becoming more rare as time passes, but it is an issue you will run into if you print frequently.
Another, and perhaps most important issue, is that 3D printed parts are not consistent. Apart from semi-frequent aesthetic flaws, you will be hard pressed to find a printer that can print structurally stable parts. In a nutshell, if the layers that make up a printed part don't adhere perfectly every time they are "drawn" by the heated nozzle, it becomes extremely easy to just pull the part into two or more pieces with very little (if any) force. When you consider that a 3D print may consist of hundreds to thousands of layers, the probability that you get bad layer adhesion on at least one layer is fairly high.
To make things worse, poor layer adhesion can be caused by an almost unending amount of things. The more common ones include:
#Changes in air temperature and breezes from drafts, air conditioners, open doors, ect. Note, this can usually be fixed by enclosing the printer in some sort of box which adds to the size and cost.
#Variations in printer filament (ie the plastic "ink"). This can be anything from changes in the composition of the plastic itself, to oil and dirt on the filament, to variations in the diameter of the filament, to the plastic having absorbed too much water from the atmosphere.
#Warping and curl caused by the molten plastic contracting when it cools.
#Poorly configured heating settings. (This one is actually rather hard to get right. To do it well, you have to use what is known as a "PID loop" which is hard to tune and another post for another day.)
#Dirty or cheap heated nozzles (unequal distribution of heat).
#Heavy print volume. (Extruding plastic through the heated nozzle cools it down. If you are at a part in your print that requires a lot of plastic all at once and you don't have a really good power supply, your nozzle will cool down below what is needed to properly adhere layers).
Now, for ornamental prints such as busts of yoda, holiday decorations, or random goofy trinkets, this usually isn't that big of a deal. But for functional prints such as coat hooks, machine parts, shower curtain rings, or anything that might bear a load or stress, unpredictable strength is a major issue (especially if you plan on selling your creations). Luckily, you can address these issues to an extent with the use of solvents and epoxies, but again, that is a post for another day.