I have a fairly new TAZ5. I switched from ABS to PETG, forgot to change the diameter of the filament, it clogged, and overextruded the tip right off the nozzle (it broke off). Now the remainder of the nozzle (the threads) appears to be stuck inside the hot end surrounded by a mass of hardened PETG.
Is there any hope for recovery? I had though maybe soaking the whole hot end in a mix of acetone and this other cement solvent (methyline chloride?) I have for an extended period. Before I do it, I need to know whether I should remove the aluminum part of the hotend and what the ramifications of doing so are. Never had it apart so I don’t want to screw something up.
I noticed they use some type of locktite on the threads for the hotend. Is that a special hi temp type?
It happens to the best of us. You can heat up the hotend to 160C and try using an ez out to remove the broken piece from the heater block.
Have you had the nozzle out before? If so, you might have over tightened it when you installed it. If it is over tightened, the heater block will over stress it on warm up and cause a fracture like that. Lulzbot torques them to 30 inch pounds to prevent this problem.
I have a crowfoot on order so I can torque mine when they need to be replaced.
I had this too last week. Did it nearly as no pick:
Heat up to petg print temp (240 for me). Take a Phillips screwdriver, slowly screw it out. Was much more easy than i thought, no resistance from the broken peace!
If you use the extractor method just remember it is a large COLD thermal mass, so move fast before the nozzle temp drops below the softened state of the filament material. Otherwise you may need to re-try several times to get it loose.
Been around metals and metalworking nearly all my life, there is no way a stepper motor extruder pushing plastic into a brass nozzle can break it. It was not machined correctly.
If you dig through the Hexagon files on devel.lulzbot.com, you will find some documentation about this problem.
The problems is that the aluminum heater block expands when it warms up. That expansion puts pressure on the brass nozzle. If the nozzle has been over tightened on instalation, the additional stress created by the heater block expansion causes a crack to form in the nozzle. As the nozzle is heat cycled for prints, the crack grows until the nozzle is weak enough to fail completely.
This failure is, or at least was in the past, covered by warranty.
If you need to change nozzles, I recommend you buy a 7mm crowfoot and a torque wrench. Otherwise you will be periodically replacing nozzles and heater blocks.
Repeating myself . Been around metals and metalworking nearly all my life, there is no way a stepper motor extruder pushing plastic into a brass nozzle can break it. It was not machined correctly.
Its a defective part pure and simple. The parts that are failing are factory installed.
Good write up. I suggest using a piece of rubber hose like gas line or vacuum line to hold the nozzle (instead of your fingers) when trying to start the threads into the hot heated hexagon part. 30 Inch Lbs is Not a lot of torque like you said. It just needs to be tight enough not to leak or fall out.
Call LB support. They should send out another toolhead or hotend.
The only time this may not apply if you are not the original owner of the machine…
A socket would be ideal for removal of the nozzle… I tried an 8mm, but it didn’t fit. A 9mm or 10mm might be perfect. I suppose, you could print a “perfect” socket too… well as long as you stay around 160C for removal and not melt the socket.
It isn’t necessarily defective. If you over stress a good part repeatedly, it can fatigue and crack.
They might have a design problem that is leading to the cracking. I run a E3D V6 on my Taz 2.1. I install the nozzles to the same felt tightness (no torque wrench) on that hot end as I have been on the Hexagon. Zero E3D nozzles have failed. There is one big difference between the two hotends. The E3D doesn’t tighten the nozzle against the heater block the way the Hexagon does. In that case the expanding aluminum heater block doesn’t have the opportunity to apply pressure to the nozzle the way it does on the Hexagon.
There are a lot of things going on in a hot end like that. Three material types with differing expansion rates being heated to high temps can cause strange things to happen.
I heated it to 230 and it came out easily with the aid of an allen wrench. Thanks for the advice.
I have already ordered a few various sized nozzles to play with. Should I install them in the unit when it’s hot as well?
Sadly, this isn’t my first problem with the unit. On the original bed the heating element separated from the glass ad was sagging underneath. To their credit, they replaced it promptly. The new one has a few small bubbles under the PEI, but it’s been ok so far.
The main extruder gear had a small issue with it being slightly warped as well. Would click randomly (skip a tooth) and within a few months had worn out the small gear on one side. I printed a new set and it’s been working sooo much better since. I’m actually seeing completed large prints.
This is actually the first clog I ever had in the unit and it surprised me. I had just extruded 50mm through it with a nice solid change from red abs to black petg. Went to extrude another 50 and snap. Amazing. Guess I had to start with a bang.
After a cold pull to remove as much filament as possible, I heat to 160 and remove the nozzle. I start the new nozzle and snug it up with wrenches at that same temp. Then, I heat to 240 and snug it again with the wrenches. That’s it.
I prefer to do the swap at the lower temp so I don’t have plastic flowing at all.
Broke off a nozzle in my Printer Yesterday. Today i followed some of what you guys said. Using a few Tools, setting my printer to 240c. and a screw extractor bit I easily removed it.
A Torx T15 is your friend in situations like this. Heat to 210C and apply gentle pressure (more than that stop because something is wrong). The Micro Swiss nickel plated nozzles have worked very well for me as a replacement for the OEM hexagon nozzle.
