TAZ 5 PLA have to cold pull after every print

I am working with a new TAZ 5. I have a lot of experience working with them in the past, but this particular one is totally fresh. I am printing with PLA and have tried temps ranging from 190-210.

My prints work fine for the most part. However, after every time I’ve printed and let the head cool down, the next time I try to print I get no extrusion except a few little spots. I cold pull the material, re-heat the nozzle, re-insert material, and then it works fine until I let it cool down again. It seems that the PLA is melted and reformed all the way up to the bolt and toothed gear that pushes against it. It seems like it may be melting too far up the filament and then getting stuck once it cools. However I can’t tell if this is really the problem, as I don’t know if it normally does this.

How do I deal with this? I never had this problem on previous machines. I have searched these forums and google for information on heads not extruding, but they all seem to only cover cleaning or cold pulling the head. I have no trouble getting it to work again, but I don’t want to have to cold pull it every single print.

I don’t know this is a good method of not (interested in hearing what others do). When I use PLA, if it sits for a little while between prints I typically heat it up past the normal temp (high for pla, like 230-240), until it starts to ooze. Extrude a little, and cool it down to printing temp, extrude 5-10mm or so and then begin printing. Kind of the same process I go through changing filaments. Not sure this is the best method or not, or even if it’s necessary. I print mostly in abs and don’t have this same ritual there. I don’t recall having the same issue you have either. This habit was formed more out of switching from abs to pla to ensure abs was out.

Might be terrible advice :wink:. I’m still getting to know my Taz.

I don’t know this is a good method of not (interested in hearing what others do). When I use PLA, if it sits for a little while between prints I typically heat it up past the normal temp (high for pla, like 230-240), until it starts to ooze. Extrude a little, and cool it down to printing temp, extrude 5-10mm or so and then begin printing. Kind of the same process I go through changing filaments. Not sure this is the best method or not, or even if it’s necessary. I print mostly in abs and don’t have this same ritual there. I don’t recall having the same issue you have either. This habit was formed more out of switching from abs to pla to ensure abs was out.

Might be terrible advice :wink:. I’m still getting to know my Taz.

I have my ending gcode set to retract some to pull the filament back.

I will usually, heat up and then extrude about 30mm before every print using the machine control panel in Cura or Simplify 3D . I run PLA consistently at 205c

Hey folks, thanks for the advice. I’ve been running the printer longer now and am still having the same issue, but am back with some more information.

The problem is still that it often stops extruding partway through a print. When I open up the head, what I find is that the teeth of the bolt have scraped out a big groove in the filament, leaving it with no traction to continue pushing the filament down. I often also find that the filament has lumped up or twisted right below the bolt, like one of those twisty straws.


So for whatever reason, something stops the filament from being able to go into the extruder. The bolt then continues trying to turn and push it down, but this causes it to get stuck and carve a groove out. But why is it getting stuck in the first place?

I’ve had this problem with PLA, PLA(H), PET, and ABS, at a variety of different temperatures and retraction settings. Whenever I cold pull, it works fine for awhile. The jam usually occurs after 1 hour of printing. If the problem was some other material remaining in the extruder, I’d expect it to happen sooner. And I’ve had times where I printed several things in a row (10+ hours of printing) without a problem. If it was some flaw in the extruder itself, I would expect it to happen more consistently.

What could be causing this?

The most likely cause of what you are seeing there if you have seen it with other materials as well (Specifically ABS), is electrical. ABS isn’t prone to bore lock. Either you have an intermittant short in the thermistor or heater core, or inadequate cooling on your rambo board that is causing issues after the machine heats up for a long period of time. Check that your fan is functional on the electronics box, make sure it isn’t inside an enclosure, and if it is, it has adequate outside air for cooling, possibly replace the fan. Also check the wiring and plugs, and consider building a new wiring harness and replacing the thermistor.

Thanks. I can confirm that my fan is running. By enclosure, do you mean a fan enclosure or printer enclosure?

I’m going to try some more ABS to see if it happens with it.

Do you have any suggestions or more info on how I can verify the wiring and plugs?

Printer enclosure.

You can check connectivity and resistance with a multimeter, or verify temperature with a point and shoot infrared thermometer. But since its an intermittent issue you may have difficulty tracking it down that way.

Thanks. Any idea if there’s any other steps I can take to confirm if it’s an electrical issue? I am also contacting Lulzbot support about this. If I can confirm it’s electrical, I’ll try to just get a new head or something. But if I can confirm it’s not, then I can keep trying other solutions.

Might sound like a random answer, but I had this issue with ninja flex on my flexy dually. I eventually figured out it occurs when the Z stop was too close to the bed initially. After adjusting it, the problem went away.

Could be that the hotend is misaligned with the extruder body. Loosen the bottom screws (need to move the fan duct), stick a piece of filament through the extruder and into the while coldhotend. Make sure it sllides in freely. Tighten screws with filament inserted. Check that the filament moves

I have a similar issue - the filament gets stuck in the extruder (just had to unscrew a bunch of parts to remove the filament from the nozzle with some pliers), but this happens very inconsistently. One day, the print stopped five times because the nozzle was jammed (with the gear grinding on the filament and creating gouges) and the next day there were no issues at all. Occasionally I’ll tinker with the nozzle, and it will print fine for two or three prints and then unexpectedly start grinding again. Model is Taz 5, hexagon nozzle recently replaced (a few months ago). Any suggestions?

UPDATE - just tried again recently, was able to follow the suggestions here: https://www.lulzbot.com/unclogging-your-hot-end and managed to force some of the plastic from the previous print out of the nozzle. However, still printing with a decreased stream.

I had a similar problem with a flexydually on a Taz 6. The nozzle wasn’t being cleaned well enough and the first layer was printed too close to the bed. The part would print fine, but the nozzle would be clogged when trying to print a second part. Try increasing your first layer thickness.

Also, check your filament!

I have had jamming and other printing issues from the filament size!

I had two rolls of filament with radically changing diameters.
One HIPS roll went from 2.1mm up to 3.5mm in different parts of the roll!!
The PLA roll went from around 2.6mm up to 3.1mm in several places.

The HIPS roll was from Gizmo Dorks and the PLA roll was from Esun.

Just another thing to look at.

I’m not sure if you have already solved this problem but I was wondering, are you using a standard print head? The one with the mini blower? I noticed on my Taz 5 I was having clogging issues and it was heat creep. The mini blower wasn’t cooling the upper part of my nozzle enough and my filament was getting soft and clogging. I would have to let my printer completely cool down and then I could print a handful of parts before it acted up again. I don’t know if this helps, but if you do have the original head, try upgrading to the Taz 6 head.

Extruder Mount: http://devel.lulzbot.com/TAZ/Olive/production_parts/printed_parts/extruder_mount_taz6/
Right Fan Duct: http://devel.lulzbot.com/TAZ/Olive/production_parts/printed_parts/fan_duct_right/
Heatsink Fan: http://devel.lulzbot.com/TAZ/Olive/production_parts/printed_parts/heatsink_fan/

And you can grab a replacement fan from Amazon: https://www.amazon.com/gp/product/B01GKKDHL2/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

And heat inserts if you don’t have any: https://itworks3d.com/product/metric-brass-heat-set-insert-plastics/

Though,if you can’t print and you don’t have another, I’m not sure what you can do. I hope this helps :slight_smile:

Just because your hotend barrel fan is working doesn’t mean it’s working properly. If you’re getting heat creep up your barrel, chances are that your little blower fan is dying - it’s a fairly common issue. Replace the fan with a 40mm axial and your pla issues should be a thing of the past.