TAZ 5 filament feed issue

Hello All!

I am in need of some help. I am running 3mm PLA, and have been running it for a few hundred hours over the last few months…until recently.

I noticed this about 3 weeks ago. When I go to extrude the filament it will only go for about 100mm, then just stops. The gear keeps turningm however, the filament wont feed.

So I tired a different filament, and when inserting it into the extruder, I found that it was really “tight” and wasnt able to feed it manually into the hotend.

I checked it for a clog, and there was nothing. Now, I have trouble just getting the filament to enter the hotend.

Any help would be greatly appreciated, I have a lot of projects that need finishing



Check the small gear setscrew on the extruder and make sure it is still down and locked. Also make sure there is about 8mm between the two washers on either side of both idler arm tension bolt springs. If it’s still not extruding after that, clean the hobbed bolt and check the hot end temperature is what it thinks it is with an inexpensive point and shoot infrared thermometer from your local tool / auto repair store (~$35-ish)

It isn’t the tension that’s problems. It will feed a small amount of filament, then stops and nothing. What I’ve noticed that’s different is that it’s really tight in the actual hotend. What could cause that little shaft to become tight?

What are your thoughts about the tightness, and the issue where it’s hard to get the filament to even enter the hotend?

Thanks again,


If you unbolted the cold end, the assembly could be offset, causing a bind. Aside from that, debris in the hotend, or it not heating correctly.

What type of filament? PLA may be more prone to heat creep issues than ABS. If heat creep, consider modding to a 30x30 box fan for the heatsink… replacing the blower. A temporary fix for PLA heat creep may be a touch of olive oil to “season” the hotend.

I’ve found that the vibrations from printing can cause the hotend and extruder to become slightly misaligned. This could possibly be the screws that hold the extruder/hotend to the mount coming loose…

In any case, to re-align or better align:

  • cold pull the existing filament
  • let the hotend cool down
  • raise the toolhead, or remove toolhead, to gain access to the bottom
  • remove fan duct
  • loosen the two bottom screws that hold the extruder/hotend to the mount
  • insert filament through extruder into the hotend.
  • tighten the bottom screws.
  • remove filament, re-insert to test for alignment after tightening screws
  • try printing

I am using PLA.

I went out and bought one of those laser thermometers. I pointed the laser at the heating element, and it registers at 150c. I had the printer set at 226c. The display on the printer shows that it was at 226, however, according to the thermometer, it was at 150.

What is causing this

Failing thermistor that needs replaced most likely.

Just to be sure we’re on the same page… You pointed the IR thermometer at the cylinder sticking out of the heat block (rectangular block with “hexagon” etching)? The heat block? Or the nozzle? :slight_smile:

Yes, I pointed it at the cylinder sticking out the heat block.

How do I remove the thermistor, I removed the cover, and it won’t budge

By the way, this community is awesome, such helpful people. Thanks guys

Normally the thermistor will just slide out. The heater core is usually the one that is the pain in the ass to remove. It shouldn’t be in there very hard at all unless some plastic made a “direct hit” on it’s hole, which could explain part of what is happening to it. Your best bet for a replacement that will fit if it isn’t under warranty is going to be http://i-t-w.com/parts/ I ordered about a dozen from a dozen different vendors, and managed to get a dozzen incorrect ones.

edit: And you’re welcome! We’re happy to help!

That explains the heating issues. I bought it back in November, so as long as lulzbot has a factory warranty, I’m good with the thermistor issue.

The other thing is the tightness of the filament going into the hotend shaft, and alignment issues.

Is there a way to properly align the hotend in the extruder so that the filament doesn’t snag?

I usually just feed a piece of the filament into the hotend. let it cool., then loosen the bolts that hold the hotend to the cold end, wiggle it a bit until it feels like it is centered, then tighten the bolts back down. If it’s still snagging at that point it might be a burr in the hotend or something.

I use a piece of filament for the alignment also… here’s the toolhead assembly instructions:

At the factory they use a rod for alignment:

I’m not sure what the “laser thermometer” is. Is that just an IR thermometer with a laser aiming aid? If so, some IR thermometers will not focus on a spot smaller than about 1" diameter. If you are aimed at something smaller, it will give you an average temperature of that smaller object and the surrounding area. This would give an artificially low temperature reading. I’m not sure if this is what is happening here, but thought I would mention it, just in case. You might be able to get a rough verification by poking a bit of the filament on to the outside of the hot end when at temperature and seeing if it melts.

Thanks everyone this is all incredibly helpful. I am going to work on it more tonight, and will update.

Thanks again

Don’t know if you got your problem solved but if you haven’t I would check the little squirrel cage fan for the extruder. I got my TAZ 5 for Christmas and the fan would not provide adaquate cooling to keep the finned section of the extruder cool enough. I assume the fan was defective. This caused my PLA prints to suffer from heat creep and fail within a short period of time after I started printing. I replaced the small fan with 40mm fan a new duct that I found on Thingiverse. The head worked great until I upgraded it to a duall head.

Also I assume your 225 temp was a test temp and not the temp you use for PLA?

Hmmm… we had a problem with the cooling fan that cooled that finned section on the Mini we bought over Christmas.

Those little squirrel cage fans do seem to have a higher than usual failure rate.

Fortunately for me, AO repaired the fan under warranty with no hassles (and unclogged the print head while they were at it). Happy with their service.

I’m going to throw one other possibility in as it was what happened to me. Everything worked fine till it didn’t. What happened on my tool head was the main printer extruder block delaminated just in front of the really thin area where the back bearing fits in.