There is a particular kind of satisfaction in a machine that can improve itself. My printer is an Ender 3, a cheap and deservedly popular thing, and this weekend it spent several hours printing the parts I then used to fix and upgrade it. A snake eating its tail, except the snake gets better at being a snake.
What was wrong
Out of the box these printers are fine and a bit rough. The bits that bothered me, in order of how much they annoyed me:
- The filament feeds through a bowden tube into a plastic extruder arm that flexes when it shouldn't, so the grip on the filament is inconsistent.
- The Bowden tube couplings are the cheap ones that let the tube creep in and out a millimetre or two as the print head moves, which messes with how much plastic actually arrives at the nozzle.
- Cable management is non-existent, and one of my fan wires had been quietly fraying against the moving gantry.
- There's no easy way to see the filament feeding in, so a stripped or slipping feed goes unnoticed until you've printed an hour of nothing.
None of this is a disaster. All of it is the kind of thing that makes a print fail at 80% on a Sunday evening, which is the worst possible time for a print to fail.
The closed loop
The lovely part is that the community has designed, and freely shared, printable fixes for nearly all of it. So the workflow is: download the model, slice it, print it on the very machine you're about to take apart, then take the machine apart and bolt the new part on. You are using the broken-ish tool to manufacture the parts that make it less broken.
This weekend's haul was an all-metal extruder arm to replace the flexy plastic one, a set of fan ducts that actually point the cooling air at the print instead of vaguely near it, a bracket to tidy the cabling away from the moving parts, and a few small clips. I printed all of it in PETG rather than the usual PLA, because PLA goes soft at temperatures you can reach near a printer's hot end and PETG holds up better to a bit of warmth and stress. Lesson learned the hard way last summer when a PLA bracket near the heatsink sagged into a sad little droop.
The bit nobody tells you
What they don't put in the cheerful upgrade videos is the tramming and re-levelling tax. Every time you take a printer apart and put it back together, you've moved something, and the first layer of every print is unforgiving about geometry. So after a morning of swapping parts I spent a fiddly half hour with a sheet of paper under the nozzle, adjusting the bed springs at each corner until the paper dragged with the same slight resistance everywhere. Then a single-layer test print of a big flat square to see where the bed was still high or low. It's tedious and it's also the difference between prints that stick and prints that turn into a tangled mess of spaghetti you scrape off with a spatula.
The PETG itself took some dialling in too. It's stringier than PLA, so you get fine wisps of plastic between separated bits of the model, like cobweb. The fix is mostly in the slicer: more retraction so the extruder pulls filament back when it travels, and a slightly lower temperature so the plastic isn't quite so eager to ooze. A few test prints later it was clean enough.
Was it worth it
Yes, clearly, or I wouldn't be writing this. The prints are visibly better. The first layer goes down more evenly, the cooling means overhangs don't droop, and I've not had a feed failure since. The whole upgrade cost a few quid in filament and an afternoon, which compared to buying a printer twice the price is a ludicrously good deal.
But honestly the appeal isn't really the better prints. It's the loop itself. You buy a tool, the tool is a bit rubbish, and instead of being stuck with a bit rubbish tool you use it to make itself better, iteratively, with parts that thousands of strangers designed and gave away for free. There aren't many hobbies where the thing you bought is also the factory that improves it. I find that genuinely delightful, and I'm already eyeing the next round of printable upgrades, which is of course exactly how they get you.