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.
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
How does one buy a CNC? Asking for… er… a friend.
I bought both my laser cutter and cnc machine from alibaba. The people on there are genuinely very friendly, know their stuff and can help you select the right machine, any addons you need and logistics. They could only ship it to a port near me on a shared container. From there I needed to handle logistics. Now a normal person can’t just pick stuff up from a port (plus the size and weight would require something larger than I can drive), so I found a local logistics company to pick it up, handle the paperwork and deliver it to me.
Shipping took a while (slow boat, shared container) and setting the machine up was a bit of work. It was packaged very well, but getting it all cleaned up and assembled was a lot of work, then aligning and actually learning to work with it was hard as well. One of the drivers was faulty and they shipped a new one from China by plane which arrived in a few days, free of charge. They were very helpful throughout the process and after buying the laser cutter, I bought the cnc through them as well.
The people I dealt with were more like middle man, not the actual people making the machine. But they were very knowledgeable, being able to tell me details and give advice. This was about 15 years ago now, so they weren’t just using AI. Both machines were around $15,000 and comparable in specs and functionality to a $30,000 machine bought locally. I still use the laser all the time, recently upgraded the brain so I could move away from the ancient Windows XP software I ran in a VM on a Linux laptop I have beside it. Unfortunately I had to sell the cnc because of the divorce from my first wife, but am thinking about getting another one.
If you have some money to spend and are looking for a deal, alibaba is the place.
Do you know if thats just for medium to large machines?
Kinda my dream to get some smaller ones to build a small printer/CNC farm
The smaller ones are usually hobby/self built. There is nowadays something like Carvera, but those seem like a lot of hassle and expense for not a lot of functionality.
In my opinion there’s no such thing as a small CNC. I have a tiny one 40x30cm working volume, I use it to create PCBs from blank copper coated plates. It’s better than what I used to do with laserprinted resists and chemical etches. But these days ordering PCBs from one of those online fabs is fast and better quality, cheap as well. I can’t get the blank copper coated plates for cheap anymore, since copper is so expensive. But small CNCs often lack the power and speed to be useful and the limited working space is a big downside as well. So when I bought one, I went big, with a lot of power, speed and working surface.
Also don’t snooze on the dust extraction required, all the material a CNC or laser removes gets turned into gas and dust particles. You need well and proper dust extraction and filtering. Especially if you do soft woods and stuff like glued panels like mdf or plywood. The glue gets in the air and rains down everywhere. This causes dust to cake up and be hard to clean. It can ruin the machine and make a mess of your workspace. It’s also very unhealthy to breathe.
People doing 3D printing forget about this as well. Sanding plastics or using materials with carbon or glass inside. The dust that comes off of that isn’t good, so proper dust protection and extraction is a must.
You can make one if you have a 3D printer and some linear rails. I have a somewhat steady supply of CNC parts through my job and have designed a CNC machine around that.
I’m have this https://www.sainsmart.com/products/cubiko.
But it’s very been eyeing some bigger machines
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…
scrape the pei bed with metal.
Walking away too soon. 😂
I went from a .4mm nozzle to a .2mm nozzle. When I went back the other way, I forgot to update the nozzle profile and despite cura knowing the line width was .4mm, it extruded as if it was .2mm forcing severe underextrusion until I figured it out…weeks of failed prints later. I rebuilt the printer like 3 times assuming it was physical.
Think of one and I’ve done it.
When I got my first PEI bed and was manually leveling, I had the nozzle hot and left it there for too long as I was doing something else and had a big burn mark. Thankfully only had to replace the PEI sheet, but I learned by lesson.
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.
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.
Forgot I’d changed the filament from PETG to PLA or vice versa. I did it twice, and not since. Took me hours to clear.
I had a long print job in ABS running overnight. At some point the part detached from the bed. While the amount of spaghetti was dissapointing, the massive blob of solid ABS covering the print head was way worse. I had to cut of the majority until i could remove all non-metal parts. Then i melted the rest of in the oven.
I thought my touch sensor for bed leveling was a bit of loose filament and I pulled it off. I had to replace the whole extruder. This was on an artillery sidewinder.
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.
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.
