New Printer Stringy PVA

[dandeluca 0]

So we just got a new S7 printer and immediately out of the box starting having trouble with the PVA support material.  Out of the bag it was very brittle and broke in the boden tube.  after clearing that we got the printer up and running, extruder 1 with the Tough PLA seems to working perfectly, but extruder 2 with the PVA support material is stringy with poor adhesion and print quality.   

 

Is this normal?  It seems like the PVA is not retracting correctly or perhaps there is some other issue.  Any advice or experience is appreciated. 

 

[Slashee_the_Cow 269]

As a mere mortal with a much less expensive printer, I can't actually print PVA, but I can offer general advice.

1. Make sure you're printing the correct temperature for that extruder and speed for the PVA.
2. Have you tried a different spool of PVA? It's possible the one you have might be a dud.

[gr5 2,176]

PLA is the easiest material to print with.  PVA is not even close.  It's going to always be at least a little bit stringy.  In general you want to keep it dry.  PVA starts absorbing water as soon as you open the bag and the manufacturers don't necessarily dry the filament (some even run their filament through a water bath to cool it rapidly) but Ultimaker brand PVA is usually quite dry.

 

Within 24 hours of leaving the spool on the printer PVA should degrade.

 

Brittle sometimes means it is too dry but I suspect not in your case.  PVA is brittle even when it's at the perfect dryness.

 

Instead - it looks like you printed PVA on top of brim.  That is bad - PLA prints nicely on top of PVA but not the other way around.  PVA does not print well on top of PLA.  You need to increase the "support horizontal expansion" to  a large enough value so it reaches the print bed.  Only then will it stay on top of the PLA (because part of the PVA structure is anchored on the print bed to help hold it in place).

 

90% of the problems people have with PVA is because it got too wet.  You can tell because you can see steam coming out of the nozzle as it prints.  Do you have 2 gallon zip bags ready to store you PVA in?  You need to do that ASAP.  Just a few days in humid air and now you have to learn how to dry your PVA on the print bed.  Also buy some color changing dessiccant - get a liter or so.  I suspect you haven't had that issue yet and may not for a few weeks/months.

[dandeluca 0]

The humidly of the room is low (under 30%) in the winter and but the spool has been out for several days.

 

 

 The printer was left running at work, but I can see it stopped with an error, not sure why it stopped though.  I have a PO in for some new spools of PVA and a drying solution.   

 

It interesting that you say how PVA does not stick to PLA.  I noticed that Cura left some 'cut outs' on the brim and I wondered why.  From what you say it must be for the PVA to stick directly to the bed, however it did not adhere to the print bed well either.  

 

I think my next step is going to be to clean everything, dry out the PVA and try again.  I can deal with a little bit of stringiness, but if the prints won't finish thats going to be a problem.

[gr5 2,176]

The PVA might be dry.  You can tell because steam comes out of the nozzle as it prints.  When it gets really bad you can hear it popping and hissing.  A little steam is okay.

 

I have an S5 and not an S7 and don't know much about that flex plate.  But special care needs to be taken for the first layer.

 

I asked some friends who have S7 and flex plate.  We'll see what they say when they get up tomorrow.  When printing on glass I always add a "glue".  I wouldn't do that for flex plate without knowing more first.  Did Ultimaker say anything about magigoo or cleaning the plate?  Or glue stick? 

 

Oils from your fingers can get on the build surface and perhaps you need to clean the plate with alcohol, soap and water, or something?  I really don't know but I'll let you know when I know more.

[gr5 2,176]

At 30% humidity the spool should survive at least a day out in the open.  Perhaps even a week but not a month.  I have found that 20% humidity isn't enough to keep PVA or Nylon dry.  16% works nicely.  I put about 1/4 cup or about 1/8 liter of desiccant in the same bag with the spool.  I use "2 gallon" (8 liter) zip locks.  I keep the desiccant in a small container with no lid.  I recharge the desiccant about once per month when I see the color changing.  Even with all that I occasionally have to dry the spool: for PVA I heat the bed to 60C, unspool just enough for the print (cura tells you how much you need), put that on the bed with the spool on top of the unspooled filament.  The spool itself won't warp if it's at least 1cm above the bed sitting on the unspooled filament).  Then cover the spool with a towel or similar (t-shirt?).  The unspooled filament will dry within about 4 hours.  To dry the whole spool takes more like 24 hours to get deep into the windings.  Maybe longer.

 

This procedure is mostly only needed for PVA and Nylon which absorb water fast.  PETG should be kept dry but is not nearly as critical.  abs, pla, ngen, tpla I find don't need drying ever and can sit out for years.

 

PVA can become noticeably worse even just after 8 hours of printing in a 40% humidity environment.

 

Often you will get bits of PVA all over the place.  Usually it's fine.  Don't abort the print unless you are certain it's a complete failure.

[Slashee_the_Cow 269]

Also worth considering is that you can buy filament dryers and many of them allow you to run filament out through a hole or something, so you could always run PVA straight from the dryer to the printer while the dryer is still running (and drying it), unless there's something about Ultimaker machines which I don't know about which stops you doing that.

 

4 hours ago, gr5 said:

Oils from your fingers can get on the build surface and perhaps you need to clean the plate with alcohol, soap and water, or something?  I really don't know but I'll let you know when I know more.

Isopropyl alcohol, it's commonly available in spray bottles for cleaning stuff. Just a couple of squirts then wipe it around the plate (and don't dawdle, because it evaporates really quickly). Also known as "rubbing alcohol" I believe is an American term for it.

Edited January 9 by Slashee_the_Cow
removed extra definition

[Dustin 130]

please dont attempt to drink rubbing alcohol "fool's vodka" - this can be quite dangerous.. 

with that said this sort of usage scenario is what the UltiMaker Material Station was designed for and might be a option to consider as well. The Material Station does active humidity control while powered on - though its not designed to dry already saturated materials.. just keep them from getting to that point for as long as possible (depends on enviroment)

[dandeluca 0]

Strangely when I came in this morning the machine did not show an error.  It was simply paused.  I pressed play and it started back up.  Idk if a staff member somehow paused it accidentally or what.  

 

Unfortunately I requested the UlitiMaker material handling station and we did not have the budget for it, maybe next year.   

 

Right now the print is continuing.   The PVA filling the void on the left looks perfect, the PVA on the front is still a bit of a mess, but getting better?  I am ordering some desiccant on my own dime so I can store that roll properly when this print finally finishes.  

[gr5 2,176]

Experts tell me you need to occasionally clean the flex plate with soap and water (but dry it completely) or IPA (isopropyl alcohol).  No "glues" such as magigoo necessary for PVA nor PLA.  Also they mentioned: as the PVA absorbs more water it sticks less.

 

It looks like the color of the PVA is changing as you get higher in the print.  Perhaps the outer meter was wetter?  That doesn't make much sense as the outer layer of filament on the spool is probably at least 15 meters of filament and this looks like only 2 meters at the most.

 

Wetter filament prints "snowier" and drier filament prints more transparent but I can't remember if PVA gets completely transparent - I think only Nylon does that.

[dandeluca 0]

I am going to dry this filament out before storage.  I am still not convinced the PVA is printing 'right' but I have been playing around with Cura settings for support and I think I see how to get better results.  PVA really failed where it printed on top of the PLA, it did best when it was building on itself or off the build plate.  There are some setting you can make to encourage the latter.  

[alfonsvh 10]

On 1/9/2024 at 5:43 AM, gr5 said:

 I have found that 20% humidity isn't enough to keep PVA or Nylon dry.  16% works nicely. 

 

Wow, is humidity that low really necessary? Ultimaker themselves claim:

Quote

If you use PVA frequently with the Ultimaker S5, the Material Station accessory offers a unique solution for storing materials in optimal conditions. Its six-spool capacity chamber controls the environment to keep relative humidity below 40% at all times. So there's no need for DIY dry boxes as well as less time spent operating the printer.

 

Edited January 10 by alfonsvh

[Dustin 130]

Material station is also has an active heating element and air circulation.
This user is printing off the back of his printer (or other means of storing the material) 

[gr5 2,176]

40% doesn't sound dry enough for me.  Look I could be wrong - I print a LOT of Nylon and the nylon and pva spools "look" the same although I rarely get them confused but still - I have strong associations between them.

 

PVA might not need to be as dry as Nylon (aka PA6).  So much of my advice, explanation is more for Nylon than PVA.  But with Nylon, 40% at room temp is definitely much too wet.

 

I suspect Ultimaker is hedging their bets in the MS description and I suspect it keeps the air usually closer to 20%.

 

I left a humidity detector in a bag and 21% was just not dry enough to keep nylon dry for months.  16% seemed to be good enough.  Again - I'm not as sure about PVA but I think they are quite similar.  They both suck water up easily and quickly (quickly meaning a matter of hours, not seconds).  Ultimaker has special formulations that do better at staying dry and I don't use Ultimaker Nylon much anymore (it is definitely better but I suffer with the cheaper brands).  I do use only Ultimaker brand PVA.

 

Also I read somewhere that it matters more what the "absolute humidity" is (not relative).  My printing room tends to be cool but is probably warmer than Ultimaker Headquarters (they like it cold!) so Ultimaker's "40%" is probably dryer than most people's "40%" as most people are probably in a warmer building.

[dandeluca 0]

I did request a material station for these reasons, but it was not in the budget.  (At least we can add it in the future)  

 

This is a school environment and it's difficult to tinker with things in front of 25 preteens. Our old Stratasys  printer reliably printed for 10 years without much intervention. 

 

 

[Slashee_the_Cow 269]

You could try buying a cheap filament dryer out of your money (I think mine cost about AU$70) and running it out of that. If that works, your argument for a material station becomes a lot stronger.

 

@gr5: So you're saying I shouldn't be storing my PETG and TPU outside in an Australian summer?

[jaysenodell 13]

I keep my house INTERIOR at about 24C in the winter and 25C in the summer. Average humidity here is 83%... in the winter. In the summer 95% is low (here's my personal weather station on my neigbor's dock). I figure I need to keep everything in an enclosure with desicant just to keep it from corroding (salt water is fun!). i start building that next week. I'm hoping that I can keep the humidity down with just desicant. 

 

Is that realistic or do I need to consider other methods of humidity reduction? 

 

Will be printing ABS, nylon, PETG for the first year. 

[Slashee_the_Cow 269]

You don't need to build an enclosure so much as just buy one of those plastic storage tubs. As long as it seals fairly well, just desiccant should be enough, but if you notice the desiccant gets full especially quickly, then you may need to take extreme measures.

[jaysenodell 13]

7 hours ago, Slashee_the_Cow said:

You don't need to build an enclosure

This is like me saying “I needed to buy a 3d printer”! The facts don’t matter and the points don’t count. Parts are already in transit 😜

 

I figured that if folks managed reliable results with a tub and desiccant I stood a chance with my “over the printer”, enclosed rack. I’m trying to avoid anything more than lighting in that section because lazy. Seem like I stand a chance of success. 
 

Thanks. 

[gr5 2,176]

You don't need to dry ABS but PETG prints better (less stringing) when dry.  Nylon absolutely must be kept insanely dry.

 

Desiccant works great as long as you recharge it.  Get the kind that changes color.  I'm hearing good things about alumina dessicant but I just have the silica kind.  Get a $10 humidity sensor as well.  Try to keep it well under 20% for the Nylon.  I aim for 16% humidity at 21C.  I use about 1/2 cup (1/8 liter) per spool (much less needed for the alumina).  Even with all this I sometimes have to dry the Nylon on the print bed.

[Slashee_the_Cow 269]

23 minutes ago, jaysenodell said:

This is like me saying “I needed to buy a 3d printer”! The facts don’t matter and the points don’t count.

I'm not sure I follow - "I needed to buy a 3d printer" is a fact. It's true of basically anyone smart enough to operate one.

 

24 minutes ago, jaysenodell said:

Parts are already in transit 😜

Then you're doing it wrong - you're supposed to print the thing, damnit. It's one of the reasons you need a 3D printer, so you can print accessories you need for the 3D printer you need.

[jaysenodell 13]

15 minutes ago, Slashee_the_Cow said:

so you can print accessories you need for the 3D printer you need.

Yes. That is the primary function of the printer. That and fishing/boat parts. that said, 2020v rail is currently hard to print. And before you point out that 2020v is overkill for an enclosure, I would offer that it is not overkill for structural frame for the next printer. One that may just be the exact size of the enclose. 
 

Other than the 2020, T nuts, screw, washers, and side panels (polycarbonates) everything else is being printed. Leveraging some Wemos D1 Mini to manage lighting, environment, power, etc. Those will be managed by Octo intercepts or custom Merlin (assuming I decide to just slaughter the mainboard on this thing). 
 

“Need” has never really been a critical part of my mental process. 

[Slashee_the_Cow 269]

2 minutes ago, jaysenodell said:

Leveraging some Wemos D1 Mini to manage lighting, environment, power, etc. Those will be managed by Octo intercepts or custom Merlin (assuming I decide to just slaughter the mainboard on this thing). 

That will be some pretty magical stuff. Especially since the language most of us use is called Marlin 😛

 

3 minutes ago, jaysenodell said:

“Need” has never really been a critical part of my mental process. 

We are kindred spirits.

[dandeluca 0]

I am updating this post.  I finally fixed the PVA issue.  I washed the PEI build plate with some dawn and water.  This despite the plate having "DO NOT WASH WITH WATER" written on it.  The PVA could finally adhere properly.  

 

Hopefully I can just stick to Isopropyl Alcohol from now on.  

[gr5 2,176]

Isopropyl Alcohol is very inexpensive and easy to find in stores.  In the USA it is found next to the bandages (in supermarkets, 7/11s, walmarts, drug stores). Sometimes it is called "rubbing alcohol".  In USA it is often colored with green dye.

 

Not only is it good at removing oils/greases, it evaporates rapidly.  Soap and water are also good at removing oils of course.