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Posted · Ultimaker 3 / PVA

Had my U3 for about 3 weeks now. PVA had been working fantastic, then I spent a few days tinkering with ABS before coming back to PLA+PVA. Now I just can't get PVA to print:

 

- During priming, the PVA pops/snaps like bubbles bursting,

- When it does get adhesion, it's stringy, but not the gossamer-stringy I'd expect from excessive temp, and it happens at lower PVA temps, the string gets in the way, and the print is ruined,

- Prime blob is huge, gets burned at the top, and doesn't get any adhesion, so the print head drags it off into the model, smears it around a bit; when it's finished the layer it retracts and travels smoothly and cleanly to the prime tower, does a prime, and drags a string back to the model, which invariably catches on printed part,

- Without raft and a prime tower, I generally get no adhesion,

- If I print PLA raft, the PVA won't adhere to it at any temp,

- If I print PVA raft, the PLA sticks to it, put then any PVA printed above the PLA is really inconsistent - bits of it are lumpy and brittle like the head was way too cold, while other bits are silk-stringy and almost magnetically attracted to the nearest PLA wall where all the PVA that can get to forms a nice little blob,

This beastie is a prime tower from a print today (the model didn't fare nearly so well):

image.png.b3111637ba33e90619c6a2a28d75cbc9.png

- Yesterday the PVA got kinda ground up in the tube, and was making a nasty, loud, cracking sound like someone snapping the a line of filament, and sure enough it stopped and looked like it had been chewed up in places,

 

Is this normal? I have a shield around the printer to try and prevent temp fluctuations, but maybe I need to put a proper enclosure around it? Is it moisture in the PVA? Is it the print head? Have I lost bed calibration 0 I've seen similar wiry-string when I had a model that had a part that was 1 layer off the bed and I wasn't printing support:

image.png.5c14284f034e12ee27c194031a727a57.png

 

PLA seems to print/adhere fine, it just seems to be my PVA that's having this problem now tho.

 

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