TAZ Head v2.1 clogging

hy

I changed to the new Toolhead because I thought I can eliminate the clogging completely with the help of the bigger cooling fan.
However I still get domrhow clogging from time to time at various heights in my prints…

I print my PLA with 195°C and 50°C on my bed.
Retraction is on, 1mm with 15mm/s speed

And still I get this kind of clogging:


What else can I do to prevent this from happening…

Andy

Are you sure it’s clogs? I thought my PLA was clogging but I found out it was a combination of my idler being a little loose/doing too many retractions in the same section of filament.

I print at 205C without issue now.

no im not sure…
so you disabled or changed the retraction or what did you change exactly?

andy

My retraction settings are 1.25mm at 30mm/s…and I’ve never stripped the PLA like your picture shows. That’s on a TAZ 6 w/ the v2.1 head.

The only thing I can think to suggest is to check your idler setting…I actually had mine cranked too tight for a while, and would get a nasty noise from time to time…maybe a partial stripping? It never failed a print though. I was basically compressing the PLA, making it wider, and it would start to bind. I printed out the idler setup block, adjusted to that, and have never had an issue since. Based on your picture, it looks like you are getting deeper tooth marks than I do but I can’t tell for sure.

Also, depending on your flavor of PLA, that temp may be a bit too low…so maybe the extruder is having to fight to shove material in to the hot end? Just a guess. I use Voltivo Excelfil PLA and it likes 205-213.

ok I checked now my idler tension and yes it was probably too firm.
And I also changed the PLA Temperature to 205 although on my PLA spool
its written to use 190-200°C…

I will try now another print for 3 to 4 hours and I will see…

Andy

You may also be either too close to the bed and or overextruding. Molten plastic is not a compresable liquid. If you try to extrude it into a solid object, it’s the equivalent of trying to spray through a brick wall with a garden hose. Check the fillament diameter against the fillament settings, and also make sure you aren’t starting your layer too close (if you have a 0.45mm starting layer set, measure a single layer on the bed, it should be close to 0.45mm with a set of calipers, etc.

hmm but too close to the bed would lead to a print failure in the first few layers or even in the first layer or am I wrong?
most of my print failures are higher up and not close to the bed.

I also reduced the extrusion from 1 to 0.98 but its hard to find the right spot but we will see…

Andy

ok now the idler is not as tight as before, Extrusion Mulitplier 0.98, 205°C.
The print failed after 1.5hours at layer 42…

Andy

Hello Gecko,
As piercet said, initial layer height, Z offset will have a lot to do with stripping. One of the issues with PLA is that as you increase resistance due to the nozzle being too close to the heat bed and the filament trying to extrude through a road block, It allows the filament to slow down in the extrusion and remain in the hot end longer than it should. This affects the PLA by transferring heat up the filament. Then the filament becomes more malleable (ever so slightly) and then increases the resistance to feed through the feed tube. Ultimately resulting in stripping.
Once this has happened then often you will heave residual filament in the hot end that has remained there too long and will crystallize. This then will add further resistance to the feeding of the filament.
Please raise the tool head off of the heat bed and manually extrude 50 to 100 mm of filament. If when it first comes out of the tool head, it tries to curl up, then it will indicate that you have clogging in the hot end and you will need to do several cold pulls to clear the hot end before it will operate correctly. If you do have the curling, then please look at this link for cold pull information:
https://www.lulzbot.com/support/unclogging-tips

Once you have done this, then set your springs on the tensioner to 5mm, in between the washers and set your Z offset up properly. A good starting point for the Taz6 is about -1.39.
Then start your print and see if you have better operation of the tool head.
Hope this may help.

thx a lot for the help!

Ok I extruded 100mm without any curling etc it was just a continuous stream of molten filament.
I also re-tuned the idler with the help of the lulzbot guide:

The bed is on the right height since all prints have straight walls from the bottom to the top. If the head would be too close to the bed the first layer would be wider then the rest.

here is a picutre of the failed print. I still can use it since I discovered the problem 3 layers later so I pulled out the old filament and put the new one in so it was able to finish the print more or less:


EDIT: Till now I always used Simplify3D.
For the next print I use Cura 20.01 with the standard settings provieded by Lulzbot…

Andy

Ok the Cura slicing did also fail… almost at the same layer height… hmm strange…
So it must be somehow a heat problem… or not?

I’m now out of ideas…

Andy

If you have a 0.5mm nozzle installed, I would recommend printing the part with a 0.4mm layer thickness at a higher speed than you have been. This will move the filament through the cold section of the hot end at a higher rate. That will keep the filament cooler if you are actually having heat creep related filament jams in the cold section of the hot end.

I have actually had to switch to 1.75mm filament to combat heat creep on my low extrusion rate parts.

Heat creep still happens with the v2.1 head? I’ve been using Excelfil 2.85mm PLA exclusively and have never had an issue. My Taz 6 has 10 full spools through it at this point, with print times typically ranging from 5 - 16 hours. Not a single failed print, and all of those hours were done at 0.2mm layer height.

Is it possible that there’s an error in the part? Maybe check it in netfabb basic or something?

I built a Taz 6 style toolhead and did have heat creep problems. I have also had heat creep problems with E3D V6 hotends so, it is possible. I imagine it all depends on extrusion rate, print temperatures, room temperature and filament type.

It would be worthwhile to print another similar model to rule out some problem there.

I really push the limits of the printer in terms of short extrusion over a long time period and this probably leads to failure.

I now have two successful prints one 5 hour and one 11 hour.
I did reduce the Outline overlap and this seems to work. However I now have really tiny holes see picture:
If I increase the value just 10% they disappear however on large prints this might result in a failure later during the print…


Andy