I decided to write this howto because it’s hard to find good information aboud changing the hexagon nozzle and I read questions about that topic at least once per week here in the forum. I was breaking my nozzle during learning it the hard way, another one wrote about breaking it yesterday. I think it’s enough, time to get a clear view on it, so let’s go:
This is no official Lulzbot Howto, I’m not related to them. Also don’t blame me if it goes wrong for you, do it at your own risk! If you have questions regarding some steps, ask first and do it after you are sure you understand everything. If you need force at some step, you are doing something wrong, stop immediately!
If you work exactly as described here, there should be nearly no risk of damaging your hot end. But in worst case, you could damage the thread of the heater block, which means you need to by a new one.
Removing the old nozzle:
Step 1: Drive your print head to a good working position
Move your print head to a position where you can comfortable work on it.
Step 2: Do a cold pull aka atomic pull
You do not want to have material left in the nozzle that could leak all over the threads or you tools, so do a cold pull. Short guide: Heat the nozzle to print temperature, for example 205° for PLA. When reaching it, push a little bit of filament through the nozzle to ensure there is no air in it. Switch off the heater and let it cool down to about 90-95° (again, valid for PLA in my case). During the cool down, push a little bit on the filament to extrude by hand to ensure it’s always filled with material from time to time.
When reaching cold pull temperature, pull the filament out off the hot end. If it’s not working or snapping during this step, try again with the cold pull temperature set a little bit higher. If you get strings of filament because it’s still molten inside the nozzle, repeat with a lower temperature.
You should be able to see the inside shape of the nozzle on the cold pull like in this picture:
Step 3: Heat up and clean nozzle
Heat you nozzle up to something higher then you highest print temperature, I recommend 260°. Clean the nozzle and heater with a pieace of citchen roll.
Step 4: Loosen the heater block from the heat breake
Using a 18mm wrench, loosen the heater block from the heat breake a little bit. Be careful not to damage wires from heater! Compare the pictures above for an approximate angle. The meaning behind this is to release tension from the nozzle thread and to prevent any torque being tranfered into the fragile heat break during the next steps.
Step 5: Remove the nozzle from the heater block
Using a 18mm wrench to prevent the heater block from rotating, and a 7mm wrench to turn the nozzle, loosen the nozzle from the heater. Use a peace of citchen paper or the tweezer supplied with the printer to unscrew the nozzle completely. Be sure to place something below the nozzle to catch it, or you will damage your heat bed (or your fingers) when it comes loose!
Step 6: Clean the heater block
Clean the lower surface of the heater block with a sheet of citchen paper, be shure not to push dirt into the thread! Fold the paper 2 to 4 times to prevent your fingers from getting burnet.
Unmount of the old nozzle completed, to be continued in 2. post in a few minutes…