PVA support keeps on failing print

[sharahamo 0]

I have been having repeated issue with PVA failing to be extruded (I am thinking because of the moisture, as I can hear sizzling during printing). Similar problem to here: https://community.ultimaker.com/topic/24295-help-pva-keeps-on-failing. At the start of the printing, the PVA extruded very nicely.  It fails at the same stage (towards the end stage) of printing, which is after 9 hours!

 

Can anyone suggest the best drying box that I can buy? I saw a few options but they are mostly taking out the material from the top and Ultimaker 3 takes material from the bottom. 

[Smithy 1,141]

I use the Polybox which can feed from the top (if you put the box on the floor) or feed from the side near the bottom, which works great if you put the box on the table.

 

But you can also use any other solution or use a normal airtight container, drill a little hole for the filament and out some silica gel packs inside. It doesn't matter which box, everything works, just keep it dry all the time.

[sharahamo 0]

@Smithy thanks for the tips. I am currently having issues where The PVA is under extruded and I have to 'mock' changing material mid print to ensure the nozzle is not clogged during printing (i.e. unload and load again).

 

I notice that the material is grinded a bit at the extruder when it's under extruded. Is it because the nozzle is clogged or is it because of the extruder? The nozzle doesn't seems to e clogged though. When I reload the material mid print the material comes out of the nozzle fine. 

[Smithy 1,141]

I think it is a partly clogged nozzle and your PVA has already absorbed too much moisture. So it is probably too soft or partly too soft. I don't think it is the feeder.

 

I would do some hot/cold pulls on your BB core, to be sure it is really clean and dry your spool of PVA in the oven or on the heated print bed covered with a towel.

[sharahamo 0]

@Smithy I have done all the proposed methods but so far the first half layers are fine (first 5.5 hours) but the rest are starting to get dodgy. I am not sure what's the cause but I feel like the PVA aren't that soft though. And I have to reclean the nozzle everytime it happens

 

I am also using about 1.2 m of PVA thoughout my print (PLA 15m). It is because the wait between the layers of PVA are too long that the nozzle starts to get clogged? 

 

 

Edited February 25, 2019 by sharahamo

[Smithy 1,141]

Could be, but the print core cools down a little bit when not in use, to avoid such things. You could try to enable the prime tower, but I am not sure if it really helps.

 

I assume that your humidity is too high in the room, so you start your print and everything is fine, but after some hours the PVA gets too wet. You should really get a dry box or in the meantime, take an airtight plastic bag, put some silica gel packs inside and open it just a 1-2 cm to get the filament out. Put the spool on the table, and print out of the bag. The feeder is strong enough to transport the filament.

[sharahamo 0]

Hmmm that gives me an idea. I should probably cut about a few meters PVA and let it be extruded from a bag (i think the full spool could be too heavy to leave on the table). I will try this and see where it gets. 

Edited February 25, 2019 by sharahamo