PVA not printing properly in S5

[pineirod 2]

Hi,

 

I have changed the hotends to the 0.8 to try; the PVA didn't print correctly, then I changed back to 0.4 and after many problems for the XY calibration now the PVA is not working well. 

 

Attached two pictures; in one we can see how the support broke and fell of and in the other, during printing a strange layer.

 

Why is this happening?

 

thanks

regards,

 

[Smithy 1,144]

PVA sticks not very well to PLA, so whenever you can avoid this, do it or play with the support settings to expand the support structure to reach the build plate.

 

Another reason could be, that your PVA has absorbed too much moisture. If PVA is too wet, several strange things can happen, like stop extruding, support structure breaks, .....

 

You should store PVA always in an airtight box and during longer prints use a Polybox or something like that.

[pineirod 2]

I was afraid about it getting too much water.

 

The PVA spool has been mounted since we have the printer (ca. 6 months). We use the printer often so it doesn't make sense to put it in and out

 

I guess there is no solution for us

 

thanks

regards,

[Smithy 1,144]

That's bad, but now you know the reason. PVA is so sensitive against humidity, that a few hours could be enough. 

But you can dry the spool on an oven or on the heated print bed covered with a towel. Will take several hours, but normally you can save the spool and print again.

 

If you don't want to take off the spool every time, buy a Polybox.

[pineirod 2]

Ahá, now I saw what a Polybox is (I was thinking something different). 70 euros, something to think about.

 

I'll put the PVA in an oven at 50ºC for two hours 

 

thanks

 

[Smithy 1,144]

I think two hours will be not enough, but give it a try.

The Polybox was just an example, it works great, but there are a lot of other DIY solutions on Thingiverse.

[gr5 2,173]

2 hours is not enough.  Set the printed bed to 80C, put the spool on top, cover with a towel.  Leave it like that overnight.

 

PVA gets soft if you go much hotter than 80C.  An oven is too dangerous.  heated bed is perfect.

 

[pineirod 2]

great

thanks for all the comments