Filament calibration successful, but filament isn't pulled in and won't "purge" - Assembly and first prints troubleshooting

RE: Filament calibration successful, but filament isn't pulled in and won't "purge"

diantris — Mon, 11 Aug 2025 09:01:37 +0000

I ended up contacting a friend. He told me to loosen the screws holding the top part of the idler setup, so that I could "lock it" in place. This part is not in the instructions. Throughout the manual, the idler looks the same as I had it put together and that is wrong.

So good news: I got through this step.
Bad news: now the printer doesn't recognise a USB. Any USB. *sighs* And it won't even print via WIFI without that USB.

RE: Filament calibration successful, but filament isn't pulled in and won't "purge"

Laxdavi3 — Mon, 11 Aug 2025 01:34:12 +0000

You may have done this already, but check the idler assembly to ensure the bearing installed can move freely. If assembled correctly, then check the idler swivel assembly. Make sure you installed the idler swivel correctly. The idler swivel should lock down onto the extruder idler. The spacer installed into the idler swivel ensures the idler swivel stays engaged with the idler. The filament should not be able to separate the idler swivel from the extruder idler. Also ensure the spring screws are tightened according to the assembly instructions.

RE: Filament calibration successful, but filament isn't pulled in and won't "purge"

CJD — Sun, 10 Aug 2025 23:11:25 +0000

For some reason I didn't see your update when I replied. No idea on this one, other than to carefully go through the assembly instructions to be sure you got everything. Sometimes starting a tear-down reveals the issue as well. Perhaps someone has encountered something similar and has a better idea.

RE: Filament calibration successful, but filament isn't pulled in and won't "purge"

CJD — Sun, 10 Aug 2025 20:18:46 +0000

Troubleshoot.

Check the wiring and connections first. Just have to work through one step at a time till you figure it out.

RE: Filament calibration successful, but filament isn't pulled in and won't "purge"

diantris — Sun, 10 Aug 2025 19:58:28 +0000

I'm doing some investigation. From what I can see, the filament gets to the gear box and idler.
The idler looks like on the photo under "6. Nextruder assembly | Connecting the heatsink cables", "49. Connecting the heatsink cables" (https://help.prusa3d.com/guide/6-nextruder-assembly_849034#856859), where the 2 parts are put together at something what looks like 45 degrees.
There is no way to place the parts together tighter. As soon as the filament reaches them, it pushes the parts away from each other. We tried loosening and tightening the screws, but nothing seems to change the behaviour.

Filament calibration successful, but filament isn't pulled in and won't "purge"

diantris — Sun, 10 Aug 2025 19:30:18 +0000

Hi,
I just assembled Core One. I went through all the self tests and calibrations and should now be able to print. The display shown "ON" on both sensors, but the filament never gets heated up or - as the LCD calls it - "purged". When I switch off the printer and pull out the entire filament, it's not even warm, so I assume it's not even getting into a spot where it would be heated up. I already tried "Retry" a couple of times, but that doesn't help. What can I do about it?