3 Extended - BB Core (Extruder 2) - PVA not adhering

[PatrickW 0]

When I print a model in PLA (Extruder 1) with PVA (Extruder 2) for supports, the PVA doesn't adhere. It just strings. However, if I print a test model in PVA only, it adheres (to the build plate) and everything prints normally.

This issue began during a 51 hour print job. Up until about 35-40 hours, it was printing successfully PLA with PVA for supports. This included PVA adhering to and printing over a PLA raft. This print stopped with the message, "PrintCore in head slot 2 is taking too long to warm up." Up until this print, I had done many with PVA supports successfully.

I've done active leveling of the build plate, updated the firmware, calibrated Z offset, and ran the heater sensor test which was OK.

Can someone please help with this issue or suggest how I can further troubleshoot?

THANK YOU.

[rebekah_harper 60]

hiya

I have a funny feeling that the nozzle is blocked and it's not extruding enough. this build up happens over time and you'll need to keep on top of.

the speed of the build up seems to increase with moisture content. I have found that dealing with the moisture solves most problems with PVA.

this is what I had where there was only 1mm hole for about 10mm. I have found a way to mitigate against moisture and have posted a solution.keeping it dry

I have sufferd like you and it eventually destroyed a core in the end. something that I strongly believe Ultimaker should devise a solution for.

[PatrickW 0]

Thank you for your reply. I did try new PVA right out of the package and the behavior was the same. Also, I think Extruder 2 with the PVA is extruding normally because when I print something PVA-only it's fine. This problem is when PVA is being printed for support of PLA (extruder 1).

[rebekah_harper 60]

You'd be surprised but I found that the default settings work fine without a clogged core so this might be the problem.

I've had nightmares with the BB core and although I am happily printing now, it does sometimes give me grief. but a clean out and we're back on track. I try and be rigged with my PVA handling.

I know from when running a Wanhao D4S it was horrible stuff to work with especially when affected by moisture. if during your print you hear popping or sometimes fizzing then you know you have a moisture issue.

the main thing with moisture that the rapid change from "liquid" to gas does two things, force it's way out and whilst doing so push a little back. as a consequence you have a slight gap in overal flow of material and therefore, especially when going over a gap, it appears that extrusion is failing.

the other thing that I found it does is cook the material within the nozzle this causes multiple layers to build up on the nozzle lining, this in turn shrinks the hole it's trying to push through.

so if it's just building up layers it's fine as it can endure the small gaps.

so I would explore the partially clogged nozzle which doesn't clear with a quick clean session via the printer settings but a prolonged session where you get a nice piont on the end of the filament.

hope you have more luck with it.

regards

Rebekah Anderson