Summary: Keep an eye on your prints in case something goes wrong. Things can get really messy, really fast. A little glue is cheap insurance for long or multiple prints.
No, I'm not talking about music here. This is what happens when your prints don't stick to the build platform. I was printing a bunch of spirograph gears. I had printed many sets before. So, confident that it would print without problem, I walked away from the printer and let it do its thing. I came back a while later to this...
|bottom view of print head|
One or more of the gears had slipped off of the build platform and stuck to the print head. The printer kept going, knocking off other gears. Eventually the nozzle got blocked by the parts, but the extruder kept going. The melted plastic oozed up around the nozzle and hot end engulfing both. It looked like a total nightmare to clean.
|this is what was stuck to the print head.|
I peeled the mass of plastic off of the print head before it cooled down. But there was still a big mess of melted plastic surrounding the hot end up inside the fan shroud. I though I would have to disassemble the entire print head to clean it. After closer inspection I could see that the fan shroud is attached by four allen screws on the outside of the print head.
|one of the screws holding the fan shroud on|
|mess of PLA around the hot end|
Once I removed the fan shroud I could see it wasn't as bad as I thought. I turned on the machine and used the advanced settings to heat up the nozzle to about 190°C; hot enough to melt the plastic, not so hot that it burns or makes a bigger mess. I gently pulled on the mass of PLA with pliers until it came off easily. With the nozzle still not, I wiped off the hot end and used a dental pick to remove the last little bits of PLA from around the nozzle threads.
|all clean and extruding properly|
With the hot end all clean, I advanced the extruder to make sure the nozzle wasn't clogged. The PLA flowed nicely so I screwed the fan shroud back on. I printed the gears again, this time using glue on the build platform. They printed perfectly. Even if you may not need it, use glue to make absolutely sure your prints don't come loose.