TAZ 4 clogging issues with PLA

I have a TAZ 4 and I’ve been having issues with PLA clogging in the extruder. I have cleaned the nozzle several times. Have heated up to 230 in order to extrude any possible remains of ABS although it’s been months since I last used ABS.
The problem is persistent in big prints. Prints that take 1 to 1.5 hours are just fine… but above that and usually around 2 hours start the problems. Twice that I have disassembled the extruded I’ve noticed that the filament seems to be stuck at at the top of the cooling rings above the extruder. My guess is that because the PLA we are using is at 200C the temperature builds up at the cooling rings and above causing the filament to expand and so causing the clogging. I know that one solution would be to buy the Lulzbot PLA which works at lower temperature and we had that working fine. But are there any suggestions/solutions to solve this? Anyone else experienced this?
I even installed a second fan to blow air to the cooling rings but even that didn’t solve the problem. It’s really annoying since my TAZ 4 is kind of useless if I can only print small prints.
Any help is much appreciated

Take a hard look at the plastic as it exits the nozzle. Does it curl at all when it comes out? It should drop straight down out of the nozzle. Grab a piece of the extruded plastic and pull it between your fingertips and fingernails. It should be nice and smooth.

If the plastic curls or you feel roughness on the extruded plastic, you still have some sort of obstruction in the orifice.

Have you tried doing cold pulls? Heat the hotend to printing temps and extrude some plastic. Cool the hotend and pull the filament out of the extruder. You will have to experiment with the temperature but when you get it right, the plastic will pull out all the way down to the orifice.

Also, make sure you have the tension on your hobbed bolt idler high enough. PLA is harder than ABS and I get better results higher pressure on the hobbed bolt.

As a last resort, you can remove the nozzle and soak in in SCIGRIP 4 10308 Acrylic Solvent.

I have successfully cleaned several nozzles with that solvent.

Here is a link for the solvent.


Hi, thanks for the details reply.
Yes the extruded PLA does curl. I will try your suggestions and come to you.

A great user mod for PLA printing with the Budaschnozzle can be found here This will help prevent heat creep with PLA. When printing PLA with a Buda, I use this mount with the fan at 100% except for the first layer.

Ah yes, the Buda. I never had heat creep problems with my Buda on PLA because my room was always cool enough. I had massive clogging problems switching between PLA and ABS with the Buda. Switching to an all metal hotend cured those problems.

UPDATE: I did print the fan duct that was suggested above and did manage to produce a 10h and another 18h print so definately big improvement. But had another clogging issue yesterday only after an hour of print. Not sure yet if this was due to the fan working at low %. I noticed that on Slic3r the default fan speed is at 35% and max at 90%. So I will change this to be 60%-100% to make sure there is enough air-flow to the nozzle and I will update.
Another thing is that I tried to print the same object with medium and fine settings and with the medium the filament was eaten half way to the print, but didn’t clog, but the result was a failed print. With the fine settings it printed fine. Disappointed with all these failed prints… I’d suggest Lulzbot should look into this clogging issues…

Lulzbot looked into the clogging issues and fixed them by switching to the Hexagon hot end. :smiley:

Bite the bullet and buy a modern all metal hotend like the Hexagon or E3D V6. I have had no clogs due to changing filament types since ditching the Buda. It ran abs great to has a lot of problems with PLA.

I did try the mod with the fan duct and for sure I got improvements as I managed to do up to 10h print. But it was not persistent maybe due to forgetting to have the fan at 100% at all times…
Anyway I’m upgrading to E3D v6 now and will be posting more details soon.
But for my experience upgrading to a new hot end is not as easy as it may look. You have to find the correct mount, make sure you connect everything correctly and then set the proper values to configuration.h and reflash firmware. Also don’t forget to store the Steps/mm settings before you flash (as I did) and also you will need to do a PID tuning. Unfortunately all these information are scattered all over the place… so as soon as I will have it working I’ll try to make a new post about this.

I have printed lots of ABS, but never got a good PLA print, I always end up drilling out the PLA in the all metal hotend. PLA hates being in my printer, and refuses to flow. Is that stuff really just colored pasta?