PVA help for a newbie

[rneumann 0]

Could someone please tell me what I'm doing incorrectly with PVA and my S3?  I've printed a few items with PVA structures that worked fine.  Now when I try printing with the PVA the machine is going through the motions, but not laying any PVA down.  Or its spitting and dragging PVA all over the bed.  I've went through hot and cold "clean out" processes.  

 

Am I doing something wrong with my PVA?  Is there something wrong with the BB core?  The PVA looks burnt when I unload and reload.  

 

I'm new to UM and PVA, so any help would be greatly appreciated.  Even direct me to a PVA tutorial if possible.

 

Thank You!!

[gr5 2,172]

PVA is definitely harder to print.  There are lots of possibilities.  I really don't like the look of all that burned PVA so maybe do more cold pulls and learn how to do them properly but lets go with humidity first...

 

PVA (and nylon) absorb water like crazy.  It's annoyingly good at it.  Just leaving PVA out on your printer for 2 days (could be a single print that lasts 2 days!) is enough to "ruin" it.

 

You know the PVA is too wet if you hear sizzling, popping, and see steam coming out of the nozzle.  Although it could be only a little bit wet and still causing issues.

 

You can restore PVA by heating it.  Set the print bed to 60C.  Uncoil enough PVA for an experiment.  Put the filament directly on the bed and the spool on top of that.  cover this with a towel or sheet or blanket.  Preferably you want a good 20cm of insulation on top of the spool (otherwise the top of the spool will be at only 30C).  Leave it like that for 3 hours to dry just the last few meters or for a day or 2 to dry the whole spool.

 

Try printing again and the first layer should be transparent.  Whenever the first layer is snowy/cloudy it probably has water in it.  Same with nylon.

 

Alternatively you have a partial clog.  Maybe use some other filament to do the cold pull.  Read a few different articles about cold pulls - written for other printers than yours to get a better understanding.  There are hundreds of articles and some better than others so read a few - that include pictures - to really understand it.

[rneumann 0]

Here was another result after cold pulls.  Should i look at a new core or cleaning filament?

[RogueWave 15]

I dry my PVA for about 20 hours before printing, then.... when printing have dryer temp at 35C

 

Try loading material process of PVA and after pressing confirm, PVA starts flowing......look for issues

 

[gr5 2,172]

Again - I'm going to say most likely the PVA is wet.  Did you try drying?  At least for 2 hours at 60C unspooled?  Just unspool 2 or 3 meters and if I'm right the first 2 meters should print perfectly.

[gr5 2,172]

Here's another thing I do.  I take a nice glass jar with a screw-on lid.  I squeeze some elmers wood glue into it and then add water.  About 20 parts water to 1 part glue (it's not exact - you can do "10 to 1" or "50 to 1").  Shake it up good then use a paint brush and paint this on the bed.  Heat the bed to printing temp (e.g. 60C) and it should dry about the same time it takes to heat up (2-5 minutes).  This provides a nice printing surface that most filaments will stick to (including PLA and PVA).

 

There is PVA (or similar chemical) in the following: Elmer's glue, hairspray.

[RogueWave 15]

Thanks for the tip on elmers wood glue watered down.......a have a about a gallon of it.......