Trouble Printing with PVA

[vtecprinting 0]

My engineering team just recently purchased an Ultimaker 3+ and I'm running into some issues printing PVA.

A lot of times the PVA is dragged across the print area, leading to support failures by the time the first layer of "real" material is printed on top. This usually occurs after a few good layers of printing, and the situation worsens as more layers are added.

I've already increased retraction distances and avoid printed parts when travelling. I've also lowered the print temperature of the PVA to help mitigate some of the oozing when the core isn't being used. Additionally, I've tried the Prime Tower and slower print speeds/printing jerks, but I see no noticeable improvement.

Now the humidity in the office fluctuates pretty badly, so that could be contributing, but I don't hear too many "pops" when the PVA is extruding. The situation seems to be getting slightly worse as time goes on.

In my most recent print, the PVA structure got very tangled, causing the Nylon layers to be pretty terrible at those interaction points.

Attached are a few pictures of the tangled mess. Usually it's not this bad. I'm monitoring the temperature inside with a thermocouple and that seems to be pretty consistent. This occurs with PLA and with Nylon.

[gr5 2,265]

Well if the pva doesn't stick to the glass then that's a different problem and easily fixed. But I'm guessing from the photos that the main problem is humidity. That was my thought before I read any of your text. Do you have an electric oven you can use to dry the PVA in? First find the softening temp of PVA. it's quite cool - maybe 50C? I truly forget, sorry. Don't let the oven get over that temp. Put the PVA in for a few hours.

Then when you are done printing with it make sure you put it in a sealed bag with dessicant. Buy some of that rechargable dessicant that you can heat or microwave back to dry again and redry the dessicant when it changes color per directions.

[gr5 2,265]

Oh and don't lower the temp during printing. That makes it not stick to itself as well.

[kmanstudios 1,120]

As you say the problem has gotten worse as time goes on, it may be absorbing more and more humidity. Follow gr5's advice. I was having some issues, and I usually have none to really speak of with PVA, and he pointed out a thing or two related to the humidity and temp and it was the problem.

Also, what is your bed Temp?

What are you using to adhere the material to the buildplate with?

[tomnagel 126]

It is generally not wise to experiment with the settings. Stay away from speed, flow, extruder temperature and bed temperature, since the default settings in Cura are chosen carefully by the printing specialists at UM.

Your PVA looks underextruded, meaning less plastic than planned leaves the nozzle.

Ambient moisture is a likely cause. Did this already happen with the first print right out of the bag?

[ultiarjan 1,223]

It is generally not wise to experiment with the settings.

I would say it's the total opposite.  The only way to improve, to learn,  is to experiment, fail, and try again.

The is no such thing as "the best" profile, there simply is not.

All Ultimaker profiles are a compromise, the profile does not know what is important for your print.  The UM3 profiles seem to be geared towards pretty looks and a shine of speed. If you print a thing for which f.e. dimensional accuracy or strength are higher priorities you need to change settings.

You'll want to control the sometimes huge temperature swings, you'll need to unhide settings and have a look at real speed settings, you'll need to understand why the UM3 and the UM2 behave so different with at the surface comparable infill settings. You'll want to understand why the default profiles cost you a ton of PVA on every print, etc etc etc...

IMHO just consider the Ultimaker profiles a good starting point, but don't  let anybody tell you not to experiment. Ultimaker would not exist today without people experimenting.

Edited July 2, 2017 by Guest

[vtecprinting 0]

Well if the pva doesn't stick to the glass then that's a different problem and easily fixed.  But I'm guessing from the photos that the main problem is humidity.  That was my thought before I read any of your text.  Do you have an electric oven you can use to dry the PVA in?  First find the softening temp of PVA.  it's quite cool - maybe 50C?  I truly forget, sorry.  Don't let the oven get over that temp.  Put the PVA in for a few hours.  

Then when you are done printing with it make sure you put it in a sealed bag with dessicant.  Buy some of that rechargable dessicant that you can heat or microwave back to dry again and redry the dessicant when it changes color per directions.

Hmm, I'm sure I could rig something up in the fab shop. Do you suggest re-heating if there are long periods of time between prints? I've only used about 50% of the 4kg roll thus far in 2ish months.

[neotko 1,417]

IMHO just consider the Ultimaker profiles a good starting point, but don't  let anybody tell you not to experiment. Ultimaker would not exist today without people experimenting.

Emoji clapping hands x4

Quote: "Cura are chosen carefully by the printing specialists at UM."

And I suppose also "and the community feedback and beta testers" right?

Edited July 2, 2017 by Guest

[vtecprinting 0]

As you say the problem has gotten worse as time goes on, it may be absorbing more and more humidity. Follow gr5's advice. I was having some issues, and I usually have none to really speak of with PVA, and he pointed out a thing or two related to the humidity and temp and it was the problem.

Also, what is your bed Temp?

What are you using to adhere the material to the buildplate with?

My bed temp is 60 degrees C and I'm using the glue stick provided with the printer for adhesion. Actually, the stick is almost out. Any suggestions for replacements?

[vtecprinting 0]

It is generally not wise to experiment with the settings. Stay away from speed, flow, extruder temperature and bed temperature, since the default settings in Cura are chosen carefully by the printing specialists at UM.

Your PVA looks underextruded, meaning less plastic than planned leaves the nozzle.

Ambient moisture is a likely cause. Did this already happen with the first print right out of the bag?

I like tweaking with the settings just because everyone's environment is different. Honestly, I find myself back at the default settings more often then not, but I'm a "learn-by-doing" kinda guy.

And no, right out of the box the PVA did pretty well. But to be fair, the early prints I did were not very complex and didn't use that much PVA.

It sounds like humidity is a pretty consistent answer across the board. I'll try some techniques for drying it out (and keeping it dry).

[kmanstudios 1,120]

As you say the problem has gotten worse as time goes on, it may be absorbing more and more humidity. Follow gr5's advice. I was having some issues, and I usually have none to really speak of with PVA, and he pointed out a thing or two related to the humidity and temp and it was the problem.

Also, what is your bed Temp?

What are you using to adhere the material to the buildplate with?

My bed temp is 60 degrees C and I'm using the glue stick provided with the printer for adhesion. Actually, the stick is almost out. Any suggestions for replacements?

The Glue Stick is a PVA based glue and it will not work well if the humidity is high. There are a lot of options to research such as hair spray, make your own PVA slurry from recycled support, water/salt mixture (by geert_2...Look him/her up to get the skinny on that), ABS slurry, etc. Depends on your needs and environment.

Even though I do have humidity issues, I recycle the heck out of my PVA support material. To the point I have more than 3 gallons of the stuff. I am even using it as a brush on masking agent now. And, I can make it as thick as I want.

And, kudos on the experimenting. For me, it is the only way to learn. The first thing I have done since my first Cura version (not long ago) is to open every command and push things. Found some nice happy accidents along the way

[tomnagel 126]

It is generally not wise to experiment with the settings. Stay away from speed, flow, extruder temperature and bed temperature, since the default settings in Cura are chosen carefully by the printing specialists at UM.

I stand corrected, this was not formulated very well. The printing profiles give a good printing result for most models. But optimisation for specific models or wishes (like mechanical properties or esthetics) is often possible.

But most people underestimate the amount of work to optimise settings for their model. It is very easy to drift off in the wrong direction, and become frustrated with the result. It takes a lot of hours to become acquainted with the printing process.

[kmanstudios 1,120]

But most people underestimate the amount of work to optimise settings for their model. It is very easy to drift off in the wrong direction, and become frustrated with the result. It takes a lot of hours to become acquainted with the printing process.

I am going to have to go along with that as well. Even after 7 months, I still consider myself quite the noob. And, you gotta be willing to waste a LOT of plastic. Getting better, but still learning bunches. And, I am still only touching 20%-30% of the controls.

I haven't even been playing with retractions and such like I see some experienced people talk about. LOL

[ultiarjan 1,223]

I think one important advice when learning about settings is to only change one thing at a time... Otherwise you'll loose track of what is causing the changed outcome.

And open up all the hidden settings... many settings depend on others which can sometimes give unpretty surprises.

[geert_2 558]

If moisture is the problem, then consider making a box with disseccant where you can put the spool *while printing*.

Find a sealed food box of suitable size, a bit bigger than a spool, make a spool holder in the center, drill a small (3.5mm?) hole for the filament to exit, and put a big bag of silica gel in it. Then place that sealed box with PVA-spool behind your printer while printing. I haven't tried it myself (no need to), but I have seen people using this for printing nylon, which is also very sensitive for moisture.

Silica gel with color indicator can be found in car shops: these bags are used to dry car interiors to prevent condensation. As soon as the indicator changes color from blue to pink, it needs to be dried in a microwave or other oven at ca. 100°C.

[ultiarjan 1,223]

https://www.youmagine.com/designs/drybox-for-pva-ultimaker3

I place them on the side, works fine, use a small peace of bowden to exit the box.

[geert_2 558]

https://www.youmagine.com/designs/drybox-for-pva-ultimaker3

I place them on the side, works fine, use a small peace of bowden to exit the box.

Exactly. I knew I had seen it somewhere...