PLA not sticking properly to PLA

[JohannesLusk 0]

Im using an Ultimaker s5 on engineering 0.15 mm layer height settings with PVA supports, the PLA isn't sticking to the PVA properly, initially it seems to work but then it comes loose and ruins the print. Any tips on fixing this? 

[gr5 1,843]

Could you show a photo please of the problem and also a screenshot of the model in cura after sliced?

 

In my experience PLA doesn't stick super well to PVA but it's usually fine.  The other way around is usually the problem (pva not sticking on top of PLA and there are settings to deal with this second issue but none to deal with the first).  Nylon and pva stick together much better.

 

Usually PVA issues involve humidity getting into the filament.  I find even just 1 day sitting on the back of the printer is sometiems enough to "ruin" the PVA.  You can dry the PVA by unspooling enough meters for your print (don't cut the filament) and putting that on the heated bed with the spool on top.  Then set the bed temp to 70C (no hotter) and cover with a few towels or blankets and then let it sit like that for 3 to 4 hours.

 

One way to tell if your PVA or Nylon is too wet is that you will see steam coming out of the nozzle while it prints and maybe hear it crackling and sputtering.  Also printed PVA should be transparent if dry - at least on the bottom layer.  If it is very snowy that is tiny amounts of water making tiny steam bubbles.