Struggles with the Nozzle

Last weekend everything was going really well with my 3D printer. I was humming along, on track to completing both cylinder heads (each head took over 20 hours to complete), and everything was gravy.

I woke up on Monday morning to find my 2nd cylinder head had gone terribly awry!

Above - the print I wanted. Below - the print I got. AKA - a comparison image showing how you can detect when your printer has a problem.

Okay, so this is definitely a first-world problem in the grand scheme of things, but I was definitely confused as to why my printer had, all of a sudden, gone haywire. From looking at the cylinder head, it was obvious that about halfway through the print (in the middle of the night) something had gone wrong. The last half of the print was coarse, porous and misaligned to the first half of the print. I talked to one of my friends who's a 3D printing genius and he suggested that the filament had gotten stuck on something and jerked the print head enough to offset it from its perceived position. In other words, the printer computer thought the print head was in a different location from where it actually was.

If your print head is barfing like this, it's time to hold its hair back while it pukes. Just kidding - it's time to clean that nozzle!

So last week I realigned all the axis and tried printing again, but I got the same results - a crappy, misaligned print. As I watched the print head dispense filament onto the bed, I noticed the filament did not flow smoothly out of the nozzle as I was used to seeing. I started to play around with the nozzle, forcing filament through and watching out it came out. I came to the conclusion that the nozzle was partially blocked - most of the filament was coming out sideways instead of straight down, and the filament that did come out sort of oozed instead of flowed.

The heating element and feeder pipe on the left; the offending nozzle on the right in a small pot of acetone.

I've never taken the nozzle and heating element apart before - and it wasn't easy to do so - but I finally got it all apart and I could see that the nozzle was clogged up. I've order some new nozzles and in the meantime I've left the nozzle and the feeder pipe (its the long metal threaded part attached to the orange heating element on the left in the picture above) in a bowl of acetone overnight to try to clear them out. This week I'll find out if cleaning the nozzle worked or if I'm doomed to replace it.

Fingers crossed I fix this one soon!