News about printing support with PVA

[makingzone 2]

Hello all,

There is someone who make more test about printing support structure with PVA ? Daid told about issues on the ultimaker (the PVA carbonise into the head). But few months later there is maybe some solutions ?

 

[hieronymus 0]

Only a couple of days ago, Daid revealed a little nugget of information in this thread:

http://umforum.ultimaker.com/index.php?/topic/3989-new-makerbot-models/&do=findComment&comment=31817

 

EDIT: HIPS is silly. I hope to push our water-soluble material soon. Pretty much prints as PLA, and only needs water to remove. It's like PVA without all the bad properties.

 

Even though it doesn't give any specific information on the material, it's pricing or availlability, it looks like Ultimaker is also pushing forward on the material sciences part of things.

Keep in mind, the true power of a water soluable material (like PVA or this new material Ultimaker is working on) is as an easily removable support material.

As such, it would only make sense when used in conjuction with a dual extrusion setup.

If I understand correctly there are only a limited number of dual extrusion UM1's operational at the moment (most who experimented with it eventualy went back to a single extruder for the moment) and according to Sander in this post:

http://umforum.ultimaker.com/index.php?/topic/3255-ultimaker²-lead-time-update/?p=31677

 

We are working on Dual Extrusion and we are planning on releasing it in a couple of months.

We can not pinpoint a date just yet. But it is in the works

 

the dual extrusion extension kit for UM2 is still a couple of months away, so it looks like news for this new material may be sparse for the next couple of months.

So for now, it looks like we'll have to be patient (which, I know, is a horrible word ), but great things may be up ahead.

 

[makingzone 2]

Hey good news !

I hope this new material will come soon !

 

[burki 1]

Interesting news!

To answer the original question: I have done a number of prints with PVA as support material.

So far i have no problems with carbonization or other: the material i have is really easy to print, at 195 or 200 degrees. it started steaming when printing at 210°, so i lowered.

One hint hough: while PVA is water solubile, that does not mean you rinse it and it's gone.

In my experience, it is mostly suitable for structures where you can reach the support material.

I have tried a piece with small holes (approx. 1 mm in diameter) that i filled with pva and hoped to dissolve.

After 12 hours submerged in water, most of the material was still there. It might be removable wherever you can reach with a brush or something similar, to remove the parts that have gone soft, so the still hard parts can be reached by the water.

It might be possible to get better results if you can keep the water in motion, and preferably warm, since both seem to help dissolving the PVA.

I remember from the old times at school, we had little heaters in the chemistry lab, that would spin a magnet when it was dropped in the solution. Something like this would probably be the best way.

When you use it to support easily reachable parts though, it works like a charm. it sticks to the PLA jsut enough to be printable, but can be removed almost without any water.

So, my conclusion so far: PVA is a good thing, and quite suited for printing with a (dual extruder) Ultimaker 1.

 

[makingzone 2]

Hey Burki,

Your feedback is very interesting ! I saw that you come from Zurich, could you tell me where you buy your PVA and it's cost ? I havn't test PVA yet, and I bought the dual extrusion kit only for printing with pva.

 

[Daid 306]

Interesting news!

To answer the original question: I have done a number of prints with PVA as support material.

So far i have no problems with carbonization or other: the material i have is really easy to print, at 195 or 200 degrees. it started steaming when printing at 210°, so i lowered.

One hint hough: while PVA is water solubile, that does not mean you rinse it and it's gone.

In my experience, it is mostly suitable for structures where you can reach the support material.

I have tried a piece with small holes (approx. 1 mm in diameter) that i filled with pva and hoped to dissolve.

After 12 hours submerged in water, most of the material was still there. It might be removable wherever you can reach with a brush or something similar, to remove the parts that have gone soft, so the still hard parts can be reached by the water.

It might be possible to get better results if you can keep the water in motion, and preferably warm, since both seem to help dissolving the PVA.

I remember from the old times at school, we had little heaters in the chemistry lab, that would spin a magnet when it was dropped in the solution. Something like this would probably be the best way.

When you use it to support easily reachable parts though, it works like a charm. it sticks to the PLA jsut enough to be printable, but can be removed almost without any water.

So, my conclusion so far: PVA is a good thing, and quite suited for printing with a (dual extruder) Ultimaker 1.

 

Oh, yes, "water soluble" is a bit wrong. How these things work. Plastics are very long molecules. Bit like fabrics. What the PVA and other PVA like material so, is the long molecules break when you add water. However, the resulting material does not dissolve in water. It turns into a sort of snot. Plastic which is no longer solid but liquid.

What worked for my print was putting it under the jet of water in the sink, washed the final bits away. (We have a lot of water pressure in our normal sink here at Ultimaker)

 

[LePaul 321]

Maybe this was covered already but...

If you are printing in PLA, which softens in water, wouldn't introducing water to remove the PVA be harmful to the print? Or are you referring to printing in ABS, etc instead?

 

[IRobertI 520]

PLA only softens in warm water (>50-60C), cold water doesn't affect the rigidity of PLA at all.

 

[burki 1]

I would assume that even if the PLA softens in warm water, it should harden again when drying.

Has anyone tested that yet?

I can only test "by finger pressure feel" and did not notice problems with the parts i had submerged for a day or so.

But i had not really paid any attention to this topic, so i will need to do a few "household" tests.

Although if anyone has some reliable testig methods, i too would be interested in insights regarding that matter.

 

[illuminarti 18]

PLA doesn't dissolve in water or soften due to some chemical process. It's purely thermal - the glass temp of PLA is around 60 degrees - if you put it in water that is at that temp or higher, it will begin to soften. Once you cool it down - in the water or out of it - it firms back up, just as it does after printing.

 

[hieronymus 0]

I apologize if my previous post implied that 'water soluable' meant dipping it in water would wash a support material right off.

As Daid very accurately described, trying to solve a plastic like that is basically like untangling the spaghetti. (breaking up the polymer into many loose monomers). What your left with, is going to be 'snotty' mess who's viscosity depends on the ratio of plastic and amount of water used.

I'm glad to hear that running it under a tap appears to be sufficiant to remove the slurry, although perhaps a more thorough aproach may be needed for hard to reach/flush places (Flushing out 'internal' support through a small hole in the bottom for instance).

The magnetic stirrer mentioned by Burki also sprang to mind from my days in the chemistry labs, although that may be best at circulating water around the outside of the print, not affecting the inside / hard to reach places.

An Ultrasonic Cleaner / bath (like the ones they use to clean jewelry) may be up to the task to reach everywhere, but I'm unsure whether the vibrations from one of those are capable of imparting heat into the print, which could soften it and defeat it's purpose. (I remember using them for a brief time when I was casting dentures and dental prostheses, but the ones we had also had a heating element to bring the water up to a certain temperature, so the fact that they came out hot to the touch doesn't really tell me anything).

All that being said, the water itself poses no danger to either PLA, ABS or Nylon for that matter (it's only the temperature that may pose a problem), so a 'water soluable' material still has a lot of potential.

 

[makingzone 2]

Burki, Your feedback is very interesting. I'll buy some PVA for test, but, could you make some tests and picture of the community. For exemple, parts after printing with pva support, and after cleaning. The idea is to see the surface quality after removing the pva support. Thanks !

 

[burki 1]

Hello MakingZone, sorry i hadn't found the time to take some pics, but will do those next days.

Talking about the surface quality:

If you let Cura create the support structure via the second extruder, you will get a fairly good quality, varying depending on the amount of material you use for the support: i assume using 100% you would get sweet surfaces, but you't waste quite some material and time.

So, if the surface quality is very important, you should create the support structure outside cura, for example by designing a support object and merge this with the original object. Thus you would get closed surfaces in the support where you need them.

Remember those two objects' designs must have the same origin in order to be merged, just like normal 2-coloured objects.

I will try to provide some pics for comparison as soon as i find the time.

 

[makingzone 2]

Hello Burki,

Thanks for your feedback. I bought (and receive yesterday) 200grs of PVA from Mexhibit. I made some tests yesterday.

I tried to print a first structure with few support. I had to relunch the print 3 times. I had to stop the first 2 print because the pva stop to be extrude. The third was good with nice result. The surface with support is not perfect, but I feel the support structure only at 30% and the gap between support and parts was 0.1. I have to retry with 50% infill of the support and no gap.

Then, I wanted to try a real test with the hilbert cube and this new parameter... I hadn't be able to print it. I'de got some extrusion troubles with the pva. The flow wasn't continous.

I tested to print the pva at 190 and 200C. The only good print was printed at 200C.

About the quality of the mexhibit PVA I have a question for you. Is this pva is soft or hard ? Mine is soft, not like flexible pla, but soft... I think that it was already exposed to a huge important of ambiant moisture. For exemple, I had moisture on the edge of the spool and the airtight bag was not complety closed.

 

[burki 1]

My PVA came in a silvery zip lock bag, and the spool was vacuum-sealed and airtight. the material is softer than PLA, but firmer than the soft PLA i have lying around (and never managed to print properly).

I print PVA at 200°. i went up to 210°, but the material started steaming , so i went down to 200 again. the PVA when printed never looks near as good as the actual object printed in PLA, and i sometimes get small air bubbles in it. But so far this has not been a problem, since i don't need it to look good, just to be there :-)

But it's good to hear you're making progress!

 

[makingzone 2]

Ok, I'll contact mexhibit because mine wasn't vacuum-sealed and as i said you, the airtight bag wasn't completly close. That's maybe the reason why I had extrusion troubles.

 

[makingzone 2]

Burki, have you got tips for printing pva ? I made some tests again yesterday without success. I tried to print the hilbert cube... During 7-8 layers no problem, the pva and the pla were print successfully, but the pva suddenly stop to be extruded... It's look no cloged, I had to stop the print then push (and force) the pva mannually to extrude again...

Maybe my troubles are caused with the moisture I found on the pva, I hadn't the possibility to dry the spool yet.

 

[burki 1]

I don't normally have this kind of trouble, yet i don't see how moisture might call it (which does not say it can't).

If you had to force it through: can it be it became too hot, so it formed the typical lump and could no longer be pushed into the nozzle? if so, you need to lower the print temperature.

Apart from that: Do you use prime tower and ooze shield? You should, by all means, so that the PVA does not rest in the nozzle for too long.

I understand that the termic stability of PVA is not as good as with PLA, so every some seconds a bit of the material should be extruded every now and then.

I had prints of up to 1 1/2 hours where the PVA caused no troubles at all.

I gather you are in Zurich, too? Maybe we could meet so we could compare the PVA, see how it feels, if i can print with yours and you with mine?

 

[makingzone 2]

Thanks Burki for your feedback and your proposal. No, I'm not coming from Zurich but from Neuchatel (Neuenburg). So it could be difficult to make this tests.

I'l try to low the printing temperature. Currently I'm printing at 200C. I'll try at 180°C.

Yes, I tried with ooze shield and Prime tower.

I'll try to dry the PVA this week and made this hermetic box (http://www.thingiverse.com/thing:72304).

I was away this weekend so i couldn't test anything. I'll keep you inform about my progress.

 

[drayson 75]

As I recently ordered a second extruder kit, I also placed an order for the mexhibit PVA.

Are there - beside the things described above - any other things to keep in mind setting up PVA for support?

Any hints are appreciated!

 

[burki 1]

Drayson, i think all important things have been said in this thread.

Looking forward to read about your experiences!

 

[makingzone 2]

Ouaaaa, I have always some troubles with this f**** PVA... lol

I dry in the refrigerator the PVA during 3 days, create the airtight pva box, and I've got the same troubles...

The firsts layers are print well, then suddenly the PVA stop to be printed. (But the nozzle is not cloged, the pva wasn't carbonise). I don't really know why it's blocking... Then I stop the print, disengaged the feeder and push manually with success... Grrrrrr !!! I think that the diam of the PVA change with my moisture trouble durring the shipment.

Burki, do you print the PVA as support with or without retraction ? I have to try with a simpler model maybe, but the hilbert cube have a lot of retraction for the support, and I suppoed that my troubles may due to retraction.

 

[Dim3nsioneer 557]

[...]

I dry in the refrigerator the PVA during 3 days[...]

 

Hmmm... I think it's not especially dry in a fridge. I would rather put it in a (convection) stove and heat it a reasonable temperature (40°C?).

 

[burki 1]

I don't event remove the spool when i don't use it for a few days. I really could not say that humidity is really a problem. At least it doesn't seem to be for me.

I didn't pay much attention about retraction, either. I just print it... I don't retract very much, though, just to keep the print time low. I don't have my settings here though, but it's really all more or less "normal".

Did you have deep bite maks in the PVA? Is your spring tension in the feeder high enough? Maybe the PVA was tangled on the spool?

I'm really sorry to hear you have so much trouble. It really works just fine for me.

Maybe you really should try some simple prints, maybe even a simple test cube with PVA only to isolate the source of your troubles?

 

[drayson 75]

As I got the second extruder kit last friday, today I got the info that my order from Mexhibit arrived too. So the only thing missing is .... time for assamble...

Hope to start testing on PVA support soon...