Changing a Nozzle
NUMBER ONE RULE—Only ever change a nozzle hot!
This is because it will ensure the heater block has expanded and also soften any filament that may be in the barrel of the nozzle, helping to prevent breaking the nozzle and or heater block.
Step 1 : Can you make things easier for yourself?
Each machine is a little different, but if you can lift out the extruder assembly your job will be easier.
In the Makerbot and Mbot machines there are two screws (see Fig 1.1) that are accessed from under the long aluminum mounting block that allow you to lift the whole extruder assembly out. Do this BEFORE heating up the nozzle ;)
Step 2 : Pre heat and remove old nozzle
Make sure the extruder is on a stable surface and can't slip, and work quickly - metal tools conduct heat. And make sure the nozzle is facing upwards and the heater block is not, for example, resting on your grandmothers wooden table!
Once it's hot, use something to stop the heater block from moving. In a dual
machine you can usual do this by putting something between the heater blocks; otherwise use a wrench to grip the heaterblock. (Fig 1.2)
IMPORTANT : Many machines have a thermocoupler or thermistror cable
coming out the back of the heater block. DO NOT CRUSH IT with your wrench.
Use a tool (ie not your fingers!) to undo the nozzle. A M7 spanner is perfect for most nozzles (see the spec chart). It is normal to have some resistance as first.
Put aside the old nozzle (again not on grandmas antique table
Step 3 : Clear Barrel—optional
If you have had a faulty thermistor/thermocoupler, or a serious print fail, it is
possible your barrel has carbonized filament in it that is just going to block your new nozzle. To flush this out run load with no nozzle on the machine. Watch the filament that comes out—is there brown or black bits in it, or a gouge on the sides. If yes keep loading. The gouge indicates burnt material stuck on the side that is scrapping along your filament.
When it looks clean run unload and put your nozzle on.
Step 4 : Put on the new nozzle
Thread your new nozzle into your heat block (thermal core). You can do this by hand at first
Still holding the thermal cores in place, start to tighten the new nozzle into the hot extruder. When the nozzle is all the way on, it will hit the thermal barrier inside the thermal core. Be careful: it can be hard to tell when you've hit the
thermal barrier, but over-tightening can strip the threads on the nozzle—so don’t be a brut about it people!
Step 5 : Put your machine back together and Print!
Once you've tightened on the nozzle, bolt the Stepstruder back into place, check your bed height/leveling and print.
DUAL EXTRUDER MACHINES : Your nozzle heights need to be even! Bring the platform as far up as it will go and check that the nozzles are at the same height relative to the platform. If they're not, you may have to loosen/tighten one or the other a little—remember do this with them hot!
For advice on choosing the correct nozzle for your printer please click the following link http:\\www.bilbycnc.com.au\bilbycncnozzlefactsheet.pdf
Bilby3D hopes you found this helpful