Not amused...  

RE: Not amused...

Does this say 47c ??

ps: I don't see any blob that makes me think heat break issues.  But ambient temps are a concern.

RE: Not amused...

Also - heat doesn't creep up from the nozzle into the heat break. Instead, heat creeps in from ambient and via the motor shaft through the gears. Mainly, the motor has a 35c temperature rise above ambient. At 25 ambient, that means a 60c motor. But if ambient changes to 35c then the motor is now at 70c, hot enough to melt PLA. If ambient is 45c, the motor is now 80c, and a serious problem for PLA.  You can reduce ambient or cool the motor: or not print PLA.

RE: Not amused...

Is that a temp or % humidity? If it is temp, this may be a bit too much for PLA.

RE: Not amused...

The larger number is humidity. (47 % on the image.) There is a smaller number for the temperature which is not readable on the image. Yesterday it was 17-18 °C so absolutely in normal operating conditions of a 3D printer. 

I use these cheap humidity/temperature gauges in my filament storage boxes to see how well the silica bags reduce the moisture in the box. (They only cost a couple of Euros for 4 pieces.)

RE: Not amused...

Posted by: @charles-h13

...

How do you prevent this?

Hi all,

yes, I  also had/have these blobs when printing with PLA (and, to a lesser extent, PETG). There are two things I do which I imagine to help:

- print PLA with the door of the enclosure open (that is going to change, since I now have the temperature control for my enclosure in a workable state)

- cool the extruder: https://www.thingiverse.com/thing:2975582 ; there are other similar designs out there

I believe these blobs come from the filament getting too hot/warm in a place where it shouldn't, and the lower the filament's melting point and the higher the number of retractions, the worse it gets.

RE: Not amused...

Jó reggelt István,

hm, enclosure? Looks like chamber larger than my living room 😉 . (Természetesen ablak nélkul).

I am used to, at the moment of preheating or starting the Z layer calibration, that during the preheating the filament (of course it was already there from the previous print) starts to leak out of nozzle - sign we are on the good temperature, how about yours?

Still I am suspecting the nozzle temperature.

From other threads I also read, that some guys had to totally disassemble the hotend and they discovered a tiny piece of filament between the PTFE tube and the nozzle (from previous large jamm) which started to affect the print after the heat went up.

But I think we are doing an uncontrolled dance - we should start our analysis structurally. 😎 Let me do a short summary:

Sou you have now:

• cleaned up the extruder from any garbage
• having Microswiss TwinClad XT heat break installed
• new Pruse PTFE tube
• printer in enclosure - btw. before move to enclosure did you encounter those troubles?
• printing in 0.3 mm layers with PLA (allways 0.3 mm?)
• jamming after 1-2 hours of print
• room or enclosure temperature as low as 14 °C  
• at the end the heat break would become too warm.
• replaced the heater block and the E3D V6 Heater cartridge.

correct me if I am wrong or add missing facts please, I know it consumes your time, but clearance of any missing detail could help.

"Explaining carefully your issue in detail, even to someone who has no clue what are you talking about, can lead you to solution" 😊 

Have a nice day

Zoltan

RE: Not amused...

Jó reggelt Zoltán,

 Looks like chamber larger than my living room 😉 . (Természetesen ablak nélkül).

Van ablaka... elöl az ajtón... 😆 

• cleaned up the extruder from any garbage -> ✅
•  
• having Microswiss TwinClad XT heat break installed -> ✅
•  
• new Pruse PTFE tube -> ✅
•  
• printer in enclosure - btw. before move to enclosure did you encounter those troubles? -> Enclosure was finished before the printer have arrived. Never used without.
•  
• printing in 0.3 mm layers with PLA (allways 0.3 mm?) -> No, I also used 0.1 and 0.2 layers as well and also printed sometimes with 0.25 nozzle.
•  
• jamming after 1-2 hours of print -> After the head rebuild, Yes. Never happens shortly after start of printing, only after an extended amount of time. 
  It doesn't mean that it always fails after an hour. I was able to print parts that took longer than 2 hours. Same material and slicer settings produced a failed print on other occasions. It would be easier to pinpoint the problem if it would always break after an hour. Of course I'm not printing large pieces all the time. A break down on a small part which nearly never happens after the rebuild would make less headache as a break down on large, time consuming pieces.
•  
• room or enclosure temperature as low as 14 °C  -> Yes. In summer it was warmer but this did not altered the frequency of jamming.
•  
• at the end the heat break would become too warm. -> Can't say after the rebuild. I guess the new heat break is not the problem as the broken print results are clearly different. (Extensive stringing due to dripping with the old heat break and clear stop of filament flow with the new heat break.)
•  
• replaced the heater block and the E3D V6 Heater cartridge. -> ✅  I was not satisfied with the old block as the thread was not good enough. There was a break in the thread and therefore the heat break and the nozzle could not be mated perfectly. Small amount of melted filament was pushed in to the thread. The new block is perfect and so the heat break and the nozzle can be properly screwed in. (As described by the E3D installation Guidelines.)
•  

Wish you a nice day as well! 🙂 

RE: Not amused...

Üdvözlöm István,

any news on the battle field? Battles won, but not the war yet? After our last communication did you have (no) success with any prints?

 Did you recognize how soft is the filament around the bondtech gears at the moment the printer stops to extrude?

1. could it be the combination high nozzle resistance combined with soft filament at the gears, which will allow them to rub  marks in filament. Too low temperature gradient between the nozzle tip and the bondtech gears.

2. or it is just a filament jamm problem - but this I do not believe much

Let me know if there is any progress.

Jó éjszakát kívánok

Zoltán

RE: Not amused...

@istvan-k5 :

It isn't difficult to explain how this is happening. People who use enclosures and print PLA must leave the enclosure wide open and some have had to install fans blowing into the enclosure to keep the printer cool.

Enclosures cause the printer to run hot; including the extruder motor.  Heat from the motor softens the PLA at the gears making the forces needed to push the filament down and out the nozzle impossible to maintain.  Jams are the natural result of the soft filament in the PTFE and upper heat break because soft filament is very sticky and doesn't slide through the PTFE or when against the metal heat break.

You need to find a way to ventilate the enclosure if you plan on printing PLA. Also, some users have found adding this fan to their extruder motor allows them to print inside enclosures, but still it only works when they leave the enclosure doors open.

https://www.thingiverse.com/thing:3339228

RE: Not amused...

@Zoltán: Jó reggelt Zoltán. The Filament arrived but I had no time to do anything yet. Maybe on the Weekend. Too many other things to care for...

@Tim: I don't think that the enclosure is a problem. I always print PLA with the door open and currently the Temperatur  is around 16-18°C in the attic and it stays like that in the chamber when I print. I have a temperature sensor in the there which is connected to my home automation and so I can log and graph the temperature. I only see a 1-2°C rise in temperature when I print currently. 

I post an update if I have time to experiment...

RE: Not amused...

I'm a relative newbie to this but what jumps out to me is the small nozzle size and the thin layers which both add up to slow filament speed which will allow the filament to get soft before the nozzle.

RE: Not amused...

Posted by: @neil-1

I'm a relative newbie to this but what jumps out to me is the small nozzle size and the thin layers which both add up to slow filament speed which will allow the filament to get soft before the nozzle.

That doesn't actually work that way. The heat break is actively cooled to ensure the temps near the nozzle are well below the filament melt point.

RE: Not amused...

Posted by: @tim-m30

Posted by: @neil-1

I'm a relative newbie to this but what jumps out to me is the small nozzle size and the thin layers which both add up to slow filament speed which will allow the filament to get soft before the nozzle.

That doesn't actually work that way. The heat break is actively cooled to ensure the temps near the nozzle are well below the filament melt point.

But if heat-creap up the filament allows it to get soft above the questionable step in the Prusa modified heat break, the filament would be able to squish out sideways leading to a clog in the neck of the heat break above the melt zone. Slower extrusion speeds (due to small diameter nozzle and thin layers) lead to allowing the heat-creap up the filament to be faster than the feed rate.

RE: Not amused...

I'm sick and been completely knocked out for a week now so nothing new here. 

A friend of mine offered me a stepper motor swap to test. That will be my next option as soon as I'm able to go to work again.  I'll keep you posted...

RE: Not amused...

Posted by: @sembazuru

Posted by: @tim-m30

Posted by: @neil-1

I'm a relative newbie to this but what jumps out to me is the small nozzle size and the thin layers which both add up to slow filament speed which will allow the filament to get soft before the nozzle.

That doesn't actually work that way. The heat break is actively cooled to ensure the temps near the nozzle are well below the filament melt point.

But if heat-creap up the filament allows it to get soft above the questionable step in the Prusa modified heat break, the filament would be able to squish out sideways leading to a clog in the neck of the heat break above the melt zone. Slower extrusion speeds (due to small diameter nozzle and thin layers) lead to allowing the heat-creap up the filament to be faster than the feed rate.

The heat break does a wonderful job keeping the neck cold. The top of the neck, base of the heat sink, is about 60c. The gradient through the neck is such that the nozzle can be at 280c and the step is still less than the PLA melt point.

RE: Not amused...

 istvan-k5

Just a few things to consider, I see the community is helping you already.

• PLA is sensitive with regards to the ambient temperature. If you are using an enclosure (like you do), then make sure the ambient temperature stays well below 30° C, otherwise your filament will start melting away before it reaches the hotend and it will eventually jam.
• Stay away from ABS and use PET(G) instead. Warping is a big issue when using ABS, and the emissions are a real concern as Styrol is toxic.

RE: Not amused...

Posted by: @wieman01

 istvan-k5

Just a few things to consider, I see the community is helping you already.

• PLA is sensitive with regards to the ambient temperature. If you are using an enclosure (like you do), then make sure the ambient temperature stays well below 30° C, otherwise your filament will start melting away before it reaches the hotend and it will eventually jam.
• Stay away from ABS and use PET(G) instead. Warping is a big issue when using ABS, and the emissions are a real concern as Styrol is toxic.

Thanks for the suggestions. As I stated already a couple of times: ambient temperature is not a problem. (Around 15-20 °C in the last weeks.)

ABS is actually a very good material if a good filament is used. I prefer TitanX and had no warping problems with it. Unfortunately PEI Sheets and TitanX LOVE each other so much that they become inseparable. But this I will take care later...

RE: Not amused...

Posted by: @wieman01

 istvan-k5

• Stay away from ABS and use PET(G) instead. Warping is a big issue when using ABS, and the emissions are a real concern as Styrol is toxic.

I would concur with this and add that if you do not have an enclosure, ABS can be near to impossible to print.  

RE: Not amused...

I forget: what is this discussion about?

RE: Not amused...

Hi Tim

it started with jamming PLA after the ABS troubles. It took a bit of side wind.😊