PLA Residue

#1
When printing my units got stuck to the bed. After several days of using a hair dryer to melt the pla enouph to remove it i was able to remove one, but it left behind a nasty residue. 2 questions. Why are my prints sticking SO severely that i cannot remove them, and 2 how can i remove this crusty residue.
Thanks
 
#2
It sounds like the heat is too high for your first layer. It is recommended that you use 199° for the first layer and 208° for the rest of the build layers as a starting point. If the plastic has burned into the plastic build sheet too badly, you may have to disassemble and flip it over or replace it. A piece of coarse sandpaper may be needed to remove the residue.
 
#3
This has happened to me when the bed was too close to the extruder on the first layers. It took a while for me to chip it off but I eventually got it off. I would shy away from heating the bed to get the residue off. This could warp your bed causing you a lot of frustration later on. I would not heat anything on my gMax using convection. Like a hair dryer or a heat gun. If any of the PLA your printer is made out of gets above 70C your parts will warp.