3D Printing Forum

Hi all,

I noticed since a while that during priming at the start of a print, the material immediately "curls" upwards and sticks to the nozzle outside. I think this was not the case in the past. Is this a sign of nozzle congestion? I haven't printed any abrasive materials and the nozzle itself is fairly new - I did maybe 25-50 hours of regular PLA printing on this one. Any ideas?

Best regards,
Reiner

Atomic pulls until everything is clean. That's the main source of that. Or, a coupler decaying making extra pressure (but not likely).

I did already do five Atomic pulls but then I will try a few more.

Do you have any recommendations for the temperature for the pulls? I used 90°C and PLA but I am unsure if this is correct.

Depends on the brand and sensor. As long the pull looks perfect (so it took out everything inside) it should be ok.

The pulls seem to be too gummy but at 85°C I had similar results. I used to have nicer ones in the past where you could see the form better.

I currently use Material4Print PLA: https://www.material4print.de/de/pla-fi ... fos_-_184/

I cool to 90C then pull on my Atomic Pulls
(Also whenever I remove filament from my Ultimaker 2, I use the Heat Up Nozzle to 200, then down to 90. Then I lift the feeder handle and yank it out)

I think I need to kick out my stock UM2 feeder again and get back to my previously used IRobertI feeder. With that one I did much more Atomic pulls like you describe when changing filament.

The filament replacement process in the UM2 is just bad. I did it twice and both times it left 7 or 8 blobs up and down the bowden tube. That sucked to clean up

I too sometimes get a curl up when priming, it can also vary with a change in temperature.
If I change material or colour I do an atomic pull always using a white filament and then I have a pull-through, ( I have a length of 1.75mm filament which is long enough to pass through the Bowden tube with 150mm to spare, to this I have glued a length of fine cord which has a loop at the end through which I fold a small length of paper towel) passing this through the Bowden tuble and pulling through the piece of paper towel or cloth, this cleans out any dust and bits before inserting a new filament.