I’m trying to figure out how nozzle changes should be done. The manual and the lulzbot store nozzle description contradict each other pretty seriously.
In most cases the nozzle is best changed when the hot end is slightly warm. NEVER try to remove the nozzle when the hot end is at extrusion temperature. At higher temperatures the threaded extension expands in the nozzle causing the nozzle to bind if turned. Heat the hot end to 90-100C. This will soften the plastic inside the hot end and allow the nozzle to be turned o of the threaded extension.
And the website (at i.e. http://www.lulzbot.com/?q=products/budaschnozzle-20-nozzle-075mm) states:
If you have already printed with your Budaschnozzle you will need to loosen the nozzle after the hot end has reached 160C. Unless heated past 160C, any ABS/PLA on the threads will influence how easily the items can be moved. Removing the nozzle with the hot end cold, with the presence of plastic on the threads can potentially damage the nozzle threads/threaded extension
When re-installing the nozzle, slightly thread the nozzle onto the threaded extension, only one thread then set the hot end temperature to 160C. Once the hot end has reached 160C finish installing the nozzle.
For those who have successfully been doing nozzle changes, I would be very grateful if you could describe how you do it (and what type of plastic you were printing, etc).