Filament feed failure

I have a pretty new Taz 6 and I’m having problems with the filament feed. The last four prints, at some point the filament won’t feed through the extruder properly and will instead just get chewed up by the toothed wheel meant to move it along. At first I thought the issue might be too much resistance going through the stock feeder tube, so I moved the filament spool on top of the printer with a dowel balanced across the top. It seems like there is not much resistance in this configuration, and yet, it still failed at some point towards the end of the print (about an hour in). I’ve tried tightening the screws that clamp it in there, but to no avail.

I’m getting tired of wasting time and filament on failed prints. Any suggestions for me?

PLA? If so, you might be having heat creep jams.

Try giving the idler screws a few turns. It should help the hobbed bolt feed filament through the heat break…

Yes, I am using PLA. What are heat creep jams?

Oof, lots of terms in there that I’m not familiar with (noob printer here).

The idler screws are the pair of screws with springs that I flip up out of the way when I switch filament, correct? I’ve tried tightening them but it doesn’t seem to solve the problem.

When you say “heat break”, is that a part of the printer or are you referring to the name of a potential issue? And is that the same thing as the other comment about “heat creep jams”?

Heat creep is when the heat from the hotend travels up the break. This causes the filament to soften near the hobbed bolt and makes it so the teeth on the hobbed bolt start chewing into the filament, rather than feeding it into the extruder. If you have a bite mark on the filament when you unload it from the extruder, you most likely have heat creep going on. PLA is affected by heat creep do to the thermal properties of the filament itself. It likes cooler temperatures, rather than warm temperatures, so it softens quicker than other types of filaments.

One thing we’ve come to find about heat creep, is if you set up a small desk fan blowing across the hotend, it helps prevent heat creep.

When you adjust your thumb screws at the ilder latch, we recommend leaving a 5mm gap between the washers where the spring fits. Chrisbap, you are correct on the pair of screws to tighten.

I have also found that adding a higher cmf heatsink fan will cure the problem if the desk fan does not.

Is the middle 40 mm fan always on? If not that’s probably the source of your troubles. Either way, reach out to the support team with more details:

Thanks for the explanation. It sounds like this may be the case then. When it fails and I extract the filament, I can see the teeth marks down the length of it, plus (usually) a chewed up spot where the hobbed bolt was spinning against it. I use the included small metal brush and/or the metal pick to clean out the teeth, and clip off the damaged part of the filament before reinserting it and restarting printing. This generally solves the problem until it (eventually) fails again.

Good to know about the screw adjustment distance, I will pay attention to that going forward. My screws are pretty close to 5mm now (when it most recently failed) but I can’t say for sure what they were at on all occasions. Not too far off is my guess, maybe on the looser side for the early failures.

I will try your suggestion of setting up a desk fan for my next print although finding a good location for that may be tricky.

I’ve never seen the middle fan fail to be on, although it is not always running at 100%. I have often seen 80% listed on the LCD display. I will take your suggestion and see what Support can suggest as this has definitely been a frustrating experience.

The 80% is the speed of the extrusion fans (the ones to the left and right of the nozzle). The heatsink fan should be on when the printer is on. So you’re good there.

I’ve set up a test print, making use of the desktop fan. Is there a risk of cooling the printed filament too much and having problems with one layer bonding properly to the next?

PLA is usually pretty good about layer adhesion. Don’t face the fan directly at your print bed and you shouldn’t have any issue. If you switch over to ABS you might face some issues with warping during cooling causing poor layer adhesion using the fan. In general if you are experiencing heat creep it is easier and more effective to toy with your actual extrusion temperature setting in Cura. Each filament has a temperature range that it can be extruded within, for most PLA the lower end of that range is around 195-200C depending on brand. You can reduce the temp all the way down to that 195C safely without worrying about wearing out your motors. If you haven’t tried toying with your print temp inside that extrusion range yet I would give that a shot before adding an auxiliary fan.

Great, the support team will be able to help. The middle tool head fan is not controlled by the Graphical LCD Controller, it should turn on when the printer is powered on.

Your comment has raised more questions for me now. When I look at my ‘Default Printing Temperature’ for this material it is set at 210 C (per manufacturers recommendation. The spool itself is labeled 190-220 C. The odd thing is that when I actually print anything, the hotend always sets itself to 180 C. I don’t seem to have a problem with this cooler temperature, but now I wonder why not. I had assumed (as a noob) that maybe the default temp just set a baseline and the individual models I downloaded and printed were modifying this for some reason. Is this not the case? Should I be alarmed/investigating this temperature discrepancy?

That temperature of 180C could be being set by your Detail profile (eg. Quick print, Standard…) instead of your Material profile, I have seen one overwrite the other before. The temperature of 210C that is automatically set by Cura is what was found, for the specific brand, to be the best middle ground temperature. This middle ground temperature is based on a wide variety of applications for the filament and different colors within the filament range. Hopefully this clears up the confusion!

I’m now using a default material, in this case ‘PLA (Village Plastics)’ which results in my printing at 195 C. I’ve also added a desktop fan blowing across the printer head/filament. To combat the room itself getting warm over the course of my print, I’ve opened a window to the outside (temperature around 0 C). It’s definitely an improvement as I can now successfully gets some prints completed (as opposed to just wasting filament like before) but I still have issues with it occasionally failing to advance the filament properly and becoming these thin, cobweb-like strands. If I catch it it time, I can reset the filament and correct it going forward, but it’s still sub-optimal since I need to watch the print like a hawk to catch it before it goes too far to recover.

nopick, is that fan 5v or 12v? Do you have a link to that fan?


I’m by no means an expert in these thing, but it occurs to me that if the slicer is defaulting to a print temperature of 180 degrees, it may mean that the PLA is not hot enough, resulting in the mechanical parts needing to push harder to extrude it, possibly causing the hobbed bolt to slip at some point. Maybe just increasing the temperature a little will cure it.

I’m not nopick but I’ll answer anyway :slight_smile: . The always on fan is 5V. The part used by LulzBot is (pick the 5V one):

From the manufacturer: c4010l05bplb1-7 3.87cfm

Same size from the same manufacturer: c4010m05bplb1-7 4.82cfm

Or the big guy (40x40x20): c4020h05bplb1-7 8.21cfm

Personally, I like Noctua fans: nf-a4x10-5v (4.82cfm) or nf-a4x20-5v (5.53cfm) and they are available on Amazon: 40x40x10 or 40x40x20

While I was on Amazon I found this one, 5.5cfm but I have no idea about its quality (but the price is right).