PLA Blob Aftermath
I'm an educator learning the ropes of 3D printing and the Prusa we purchased earlier this fall. I've been able to troubleshoot much of what I've encountered, but my latest challenge, similar to @bbrox's recent post, has me a bit more concerned.
I received an email from a colleague notifying me that a PLA blob had formed from a failed print. I had encountered one of these before and removed most of the filament from the first fail. Since I purchased the printer assembled, I'm a bit hesitant to take the printer head apart. However, I noticed what looks white mesh or twine on different spots of the hotend. I've attached some pictures for reference and was wondering what, if any, next steps I should take.
RE: PLA Blob Aftermath
You may have gotten off easy. It looks like the fan shroud was the only serious casualty, and you can print a replacement.
I'm not sure what the white fibers are although it looks a bit like some of the insulation off the red heater cartridge wires. Do self-tests to verify the thermistor and heater cartridges are functioning properly. If so, the mess on the heater block will clean up with some careful use of a soft brass wire brush and toothpick or strip of cardboard around the delicate wires. I found it easiest to remove the hotend for access when cleaning.
Consider a silicone sock for the hotend to deter errant filament from sticking. You might still get a spaghetti monster, but that beats the Blob of Doom. Also, be sure to observe the first layer at minimum to ensure you have good adhesion before leaving unattended. Some sort of video monitoring is recommended (see Octoprint).
Be aware that this is likely to have made the heater cartridge, thermistor and possibly the heatbreak very difficult to remove due to caramelized filament working its way into every opening. If you find yourself having to replace any of these hotend components in the future, have spares of everything on hand. I had to replace the heater block, thermistor, heater cartridge and heatbreak when the block stripped.
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He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: PLA Blob Aftermath
Thank you, @bobstro. I was able to dislodge the fan shroud from the blob, so I've gotten off even easier. We're looking into Octoprint now. I never would have discovered that if not for the blob, so if the printer functions fine post disaster, this resource alone was worth it.