Mount the new nozzle
Step 1: Insert the new nozzle
With you hotend still at 260°, screw the new nozzle at least one turn into the read with your fingers. Be careful not to hurt, but don’t use tools as you may damage the thread with them. Don’t hurry, you have about 5s…
Step 2: Screw the nozzle to the heater
Screw the nozzle mostly into the thread, this is best done with the tweezers. For the last turn, to have more feeling about torque (remember: don’t apply torque!), use the 18mm and 7mm wrench as in step 5 above. Hodl the heater in position with the 18mm one. Hold the 7mm wrench as short as possible with only 2-3 fingers. Slowly turn it, until you feel the nozzle reached the heaters surface. Stop here, or you may strip the thread!
Step 3: Turning the heat break against the nozzle to “seal” the connection
This is the step that prevents leakage during your prints. Grab the hot end with your sheet of paper and screw it to the heat break. Only hand tighten, never use the 18mm wrench or I promise you will need a new hot end! Be careful not to turn the heater block too far, have a look at the heater wires. If you can’t tight it in a good position, that’s due to length tolerances of the nozzle. Don’t worry, skip to the next step and come back to this step later.
Why it won’t leak this way without any torque? Your hot end is at a temperature during this procedure that is higher then your print temperature, you remember? If your heater block gets cooler, it will shrink, pressing the heat break and the nozzle together. This prevents it from leaking.
Re-orientate the hot end to safe the heater wires
First: Be careful in this step, I consider it the most dangerous step of this howto regarding the posibility to break something.
If you recognise you can’t hand-tighten the heater block in step 3, you have to turn the heat breake inside the cooling fins. There is no thread in there, it’s only fitted together and clamped with a small screw on the back side of the cooling block.
Turn off the heater and wait until it is cooled down completely. Loosen the small screw, but don’t remove it. See the picture to know where it is:
There is a small flat area above the thread of the heat breake that goes into the heater. Grab it with a wrench, slowly rotate it a few degrees to the position you need. You might need a little bit of force, but not too much. Be careful, the heat breake is fragile! Hand thighten the small screw again. Heat up to 260° again and continue with step 3 above.
You might not have a small wrench for that like me. You can also grab the heater with the 18mm wrench and rotate it this way. It worked for me, but be careful.