Is PVA always a headache?

[dmahalko 0]

This is basically our first ever use of PVA. Brand new roll of Ultimaker PVA straight out of the shrink-wrap, loaded this afternoon on an Ultimaker 3 Extended.

 

ThingiVerse: Spiral Chess Set with hollow base

• https://www.thingiverse.com/thing:1264417
• Printing the King piece, PLA with PVA support and raft.

 

Results about 80% of the way, appear to be... not great.

• PVA "chunks" scattered all over the bed, falling off from ... somewhere.
• PVA filament blobs all around the object.
• PVA tail seen sticking out about 5mm from the extruder head while it is using the PLA.
• PVA extruder head is completely carbonized black..  it was new and unused about 5 hours ago.

 

[gr5 1,140]

The bits of pva all over the place is 100% normal.  Unfortunately.  and the tail.

 

However you should be using the default settings which include "horizontal expansion" set to 3mm.  And I don't think you are using that.  I find it a bit dangerous to have pva start and stop like it does in your print but if you increase horiztontal expansion then pva will have a path through itself down to the glass.

 

If you don't have a path down to the glass then you have pva sitting on top of pla which works but not as well.

 

Anyway this particular part does not benefit from pva as much as some parts do that have much larger, more serious overhangs.  Like say a boat propeller would have.  A boat propeller benefits greatly from pva.  A totem pole benefits also but not as much.

 

But, yeah, pva is kind of a pain.  It doesn't behave as well as PLA.  PLA sticks to itself when still liquid.  Like mucus or snot.  PVA not so much - more like cement.  Or peanut butter.  When it's wet it can hardly hold it's own weight.  One of the results is bits of pva chunks everywhere.