I’ll start off with a recent one. I forgot to connect the hotend cooling fan when remounting the hotend. After a while the printer jammed and the whole toolhead got so hot that it started to melt. The brass inserts were coming out of their sockets and the hotend stood at an angle instead of straight down.
I also noticed that the “teflon” tube connecting the extruder to the hotend was not in fact teflon. The slowly melting ABS was blowing a bubble in that tube and it was clearly starting to melt.
It was quite a pain in the ass to fix as I did not have a second toolhead nor a second 3D printer to print a new one so I had to fix the extruder/hotend in place using 2-part glue hoping that the printer lasts long enough to print a new toolhead.
I should probably have either a thermal fuse or a smart filament sensor that notices jams as well. When your hotend cooling fan fails, or the operator forgets to connect it, the filament will jam in the heatbreak and if it goes long enough the whole hotend will be plastic-meltingly hot. A jam sensor should see it before the toolhead starts to melt.
The tube that turned out not to be PTFE is a nasty surprise. On the fan side, if you run Klipper:
heater_fanonly switches the fan on above a temperature, it can’t tell that the fan is unplugged. A fan with a tachometer wire andtachometer_pinset at least shows you the RPM, and you could add a macro that pauses the print if it reads zero while the hotend is hot.The low-tech version is to look at the heatsink fan spinning after any toolhead work, before the first heat-up. Cheap habit compared to rebuilding a melted toolhead.
This isn’t my hobby printer, but I once was trying to diagnose a filament feed issue with one of the Stratasys printers I run at work. This particular machine was always touchy about filament change overs (its a 4-bay F-370) and it of course failed when changing from empty spool 1 to half full spool 2. I tried remotely re-trying the filament load but it just kept complaining, so I went out and tried to manually feed the filament multiple times
It took me like 30 minutes of this to realize the feed tube had just come undone from the back of the spool drawer and I had fed 50 meters of filament into a huge tangle under the machine…
Think of one and I’ve done it.
Trying to print dual colour on a single colour printer, but then forgetting the pause layer to manually swap the colour. Ending up with single colour print,
That is…pretty minor compared to some of the catastrophic mistakes here haha.
Aside from printing large items without an enclosure — in the beginning I used to pull off stray filament from the nozzle with my fingers. Burned myself a few times before assigning dedicated tweezers for the task.
Printing CF-PETG on glass. It becomes one with the buildplate.
I’ve heard that said about PETG in general before. Personally I never had any issues though. Is it worse when printing CF-PETG?
Yes, it’s way worse. I made this mistake on a couple different glass beds of differing thicknesses, and each time, the print was so fused to the bed that it was impossible to remove without breaking the glass. One or two times, I completely shattered the glass. Another time, I went super slow and tried to get some warm IPA to wick under it, which sometimes helps prints release, and when I eventually got the print off, it still took a large chip of glass with it. It’s not even “adhesion”, it’s like the carbon fibre diffuses into the glass and creates some kind of next-level bond, almost epoxy-like lol.
Thinking that I could do my own research using Google and find a good printer (which I have always been able to do when purchasing electronics in the past), but not realizing how widespread fake reviews had become, and that most youtubers produce heavily biased reviews to stay on good terms with the manufacturers who are sending them free stuff.
I started 3D printing…. Now I have 6 printers, a cnc and a laser engraver that also does cmyk printing
