Core One filament jam
Whenever I print long (@ 5 hours) print jobs in PLA, the second print has the filament jam at about 10%-25% into the job, but the printer does not recognize the jam and keeps printing nothing. Since these are not very tall objects (MultiBoard grids), it is not easy to spot that there is a problem with the Buddy camera image. So I only discovered the problem when I went to the printer room to retrieve that print or a different print. I was under the impression that the Core One could catch such a problem. The first time it happened, I was printing with Voxel PETG, so I thought the filament was wet and dried it, only to have it happen again. I am having the same issue printing with Voxel PLA. I have no problems with either filament on my MK3.9S. I am using the standard 0.2 Structural profile with infill at 20% and 3 perimeters, my standard MultiBoard profile.
With every jam, I find that the filament below the drive gear is stuck at the top of the lower path, and the upper filament is stuck just outside the top path, which requires the removal of the drive gears and lowering the nozzle to get access to the stuck filament. This is a real pain...
Any suggestions on what I might have to do to fix this?
RE: Core One filament jam
Did you have the door closed or open?
What was the temperature inside?
Based on your description, I would suspect heat creep.
Did you perhaps overtighten the knurled screws securing the hotend? There was a case where they were tightened so much that the nozzle tube was permanently deformed.
Do you have another nozzle to rule this out as a fault?
RE: Core One filament jam
Thank you for your response. The door is always closed, not sure of the temp in the chamber, but I have a filter on the fans, so I always have the fans running (25% - 50%). I'm sure there is no distortion, as the first print always works just fine. I don't have an additional nozzle though, so cannot swap to see if that is the issue. I have printed the same file on the MK3.9S with the same spool, with no problems.
RE: Core One filament jam
Thank you for your response. The door is always closed, not sure of the temp in the chamber, but I have a filter on the fans, so I always have the fans running (25% - 50%). I'm sure there is no distortion, as the first print always works just fine. I don't have an additional nozzle though, so cannot swap to see if that is the issue. I have printed the same file on the MK3.9S with the same spool, with no problems.
Depending on the type of filter, the airflow might well be too restricted to keep the chamber temperature within range. You can check the chamber temperature while printing; actual and target values are displayed in the lower right of the screen (in small print). If the screen has switched to the 3D view of the current model, just nudge the encoder to bring back the detailed status display.
You do keep the top vents open for PLA and PETG, right?
RE: Core One filament jam
Doesn't the MK3.9S use the same nextruder? So you could swap them nozzle with the CoreOne. I have read on the forum that some people have issues with the HF nozzles.
Thank you for your response. The door is always closed, not sure of the temp in the chamber, but I have a filter on the fans, so I always have the fans running (25% - 50%). I'm sure there is no distortion, as the first print always works just fine. I don't have an additional nozzle though, so cannot swap to see if that is the issue. I have printed the same file on the MK3.9S with the same spool, with no problems.
RE: Core One filament jam
Yes, it does, but I'll have to wait until the 5-hour print job it is doing is finished.
RE: Core One filament jam
I would recommend leaving the lid and door open the next time you print.
If that doesn't work, try the nozzle next time.
It is best to take only one step at a time to isolate the fault.
RE: Core One filament jam
Sounds like heatcreep, yep.
What filter solution are you using? If you're using the official Core One filtration you kit, ignore most of my post!
I've printed the cnc kitchen box with a 13x5 cm HEPA filter + Nevermore and the fans need to run at 60-80% to keep the chamber from going above 40°C with just the intake lid open and 21°C room temperature. Sounds like a jet engine though...
So before checking the nozzle etc., check the chamber temperature! It might be over 40°C, which might already lead to PLA becoming a bit too soft to get pushed by the extruder.
The stock chamber fans have very decent airflow, but if they need to push through something like a HEPA filter, they crumble. You need a radial fan for it, like the one in the Prusa filtration kits.
RE: Core One filament jam
I have the CNC Kitchen filter system, so I'll try to make sure that the fans are on higher than I have been. I have another print to do today, so I'll test it out and check the chamber temp.
RE: Core One filament jam
I have the CNC Kitchen filter system, so I'll try to make sure that the fans are on higher than I have been. I have another print to do today, so I'll test it out and check the chamber temp.
Yep, if it's a HEPA filter insert (i.e. with very small pores), too little airflow and hence to high chamber temperature is a very likely cause of the problems you observed. The stock chamber fans are not meant to push air against any kind of resistance and their airflow will largely collapse.
CNC Kitchen mentions a 65% fan setting on the Printables page for the filter, and claims that this resulted in a chamber temperature of 32°C. Unless he works in a rather cool room I am skeptical of that number and would expect higher temperatures even at the elevated fan setting he proposes.
If you really want a HEPA filter when printing PLA, you might have to bite the bullet and buy Prusa's solution with the extra fan. It's a different fan type which is suitable for moving air against the filter's resistance.
RE: Core One filament jam
I have the CNC Kitchen filter system, so I'll try to make sure that the fans are on higher than I have been. I have another print to do today, so I'll test it out and check the chamber temp.
Even with the Prusa fan, the temperature rises quite quickly, depending on the ambient temperature.
Therefore, as already mentioned, simply leave the lid and door open.If it then works, you can think about a solution.
If you have the CNC Kitchen filter, you can set the fans to 100% and it will still get too warm inside.
RE: Core One filament jam
It appears to be heat creep, but with an 11-12 week delay on receiving the Prusa filter system, I'll just print with the top open. I'm hesitant to do that as my print room is in the basement where my woodworking is located, and I have to contend with dust in the area. Guess I'll place a filter over the open top to reduce the dust. I'll also remove the HEPA filter from the CNC Kitchen filter and settle for just having the activated carbon. Have to print a grid to hold the activated carbon in place.
RE: Core One filament jam
Why don't you just remove the filter when printing PLA or PETG and use the chamber fans and top vents as designed?