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FalmouthLouis

Optimising support structures: Central repository for advice: PVA, Breakaway

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Posted (edited) · Optimising support structures: Central repository for advice: PVA, Breakaway

I've posted a couple of queries about the workings of PVA and Breakaway. In the course of this, I've been encouraged to explore the mind-boggling array of options in Cura for tweaking support structures. This would suggest that, within the Ultimaker/Cura community, there are people who have given a lot of thought to how support structures can be optimised. However, a moderately experienced operative like myself is just bemused as I look at the checklist of options.

 

I now have a decent amount of experience with printing supports in either PLA or Breakaway. Some initial thoughts

 

1.  It's generally easiest to print supports in Breakaway, which is easier to store (not hygroscopic) and stable to print.

2.  If the support structure has relatively narrow slots/crevices/indentations it can nbe hellish getting the Breakaway out, and I have deliberately used PVA on occasions to get round this problem.

3.  Breakaway does require a certain amount of force to release it, so it is not suitable for supporting fragile/thin designs. But this raises the question of whether there are choices within Cura which will reduce the adhesion between Breakaway and supported surface. There are options to do with Z distances which suggest you can widen the key gap - but just how far can one go with widening this?

4.  There are a whole lot of issues to do with PVA's chemical composition. It absorbs moisture and starts printing badly as a consequence. How best to store? Does it age badly? I had past problems with clogged BB nozzles, though this may have been brought about by my inexperience.

5.  Whereas I have printed support structures in Breakaway which have gone up to the 120 mm height region, I don't think I have ever got a PVA structure to print above 400/500.  I've discovered an option which allows one to print a brim specifically round the support structure which may help me a bit. However, I sense that, even with a prime tower, PVA structures tend to be sensitive to sideways pressures from the printing process (some relatively narrow PVA columns have recently been knocked off the vertical pretrty easily).

 

As far as I am concerned, there are a whole range of issues with support structures and I don't know anywhere to turn to for serious advice on optimising this part of the printing process.

 

I'll use this strand to feed my further experiences in. I hope the Ultimaker/Cura team can provide some tips as well

Edited by FalmouthLouis

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Posted (edited) · Optimising support structures: Central repository for advice: PVA, Breakaway

What works quite well is to only print the support interfaces with Breakaway.  That avoids the mess Breakaway often makes, with curls of filament everywhere and sometimes stuck in the print. It also minimizes the use of the rather expensive Breakaway filament, as well as reducing print times (by reducing nozzle changes). Thereby you also avoid problems with tall support structures, as these will be printed with the "normal" filament anyway. I imagine that this could also work with PVA, but I don't have too much experience with that.

Edited by P3D

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

Thanks P3D: A lot of the time, I'll be printing to support sloping or curved surfaces, so pausing to change some layers to Breakaway doesn't make much sense. In general, Breakaway prints pretty well, and I've just printed a marionette head which needed both external scaffolding and very light infill so that it supported the roof of the head and could be carved away. Breakaway worked fine for both.

Breakaway.jpg

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

I've just been reminded about why I don't like PVA. I've got a commission to print ten of these handles you can see below. They need to be in nylon and whichever way they're printed, some support is needed. I've had bad experiences with Nylon and Breakaway, so decided to print these with PVA supports. My first print of three went fine. My second print of three had problems with nylon warping, probably because I hadn't done enough magigooing. After aborting, I started another print and the PVA refused to flow. It turned out that some had got stuck in the drive mechanism, so I had to disassemble that, which is a fiddly job. I did a hot pull on the Print Core just to be sure, but the PVA then loaded but wouldn't flow. I then gave it 6 hours at 50 degrees in my tame food dehydrator, and it's currently printing smoothly.

 

The lesson from this is that PVA can get snarled up in the drive mechanism in the middle of a routine job. My conclusion is that I have to work much harder on keeping PVA dry. However, this is a hassle when PVA feeds into print core 2, which means that you have to shift the filament feeding into Print Core 1 to get at the PVA reel. ....in any case, feeding filament into UM3s is still pretty fiddly if you're pressed for space. I'll keep working on PVA because I have a job coming up with a lot of relatively fine struts and beams which would be unable to withstand the forces involved in stripping Breakaway away. PVA will be the only way forward, but these will be prints lasting days so I am nervous.

 

 

Kayak.jpg

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Posted (edited) · Optimising support structures: Central repository for advice: PVA, Breakaway

Pva is extremely sensitive to moisture / exposure. (sometimes it takes only hours to be "contaminated")

At this moment, i use the length indicated by Cura, add about 2mtr's (for the S5), and take that of a roll PVA, (Polymaker S1)

This length is feeded into the S5, and the rest of the roll is put back in a sealed bag with silica gel.

I lose some 10% on a roll this way, but i have almost no bad prints due to moisture, and my roll is used to the end without drying.

 

There should be more education about 3D printing and the influence of moisture. Pva is probably an extreme example, but many other filaments are sensitive to. 

 

 

Edited by RudydG

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

I'm having steady problems with PVA failing part way through jobs. It's clearly to do with dampness, even though I am using a fruit dessicator to dry reels in advance of the job. I found the following exchange to be pretty useful. I've got a spare Polybox so I'll bring that into action. Will report back.

 

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

following.

PVA is the biggest challenge for me, and if the 3D printing community really desires the "spreading" of the technology, should ease this matter, as an critical point.

My biggest step in this point was when I started drying the PVA. I'm using a fruit dehydrator, before printing and also during printing.

Another improvement, due to the using of PVA generates so many problems, i only use PVA as a "Support interface" (2-3 layers).  This also reduces the impact in the cost.

An to reduce the problem of clogging:
Big retraction (direct extruder) but slow: 8 mm; 15 mm/s

Temperature as low as possible: 175º (recomendation manufacturer: 180-210). Going to Standby temperature always: 160ºC
Big big purge before printing: Prime tower minimum volumen: 20 mm3. (tower size: 20 mm)


Now, the next points very important to adjust the settings:
- the position (XY) of the extruder while tool change. But this is something that I still can't control. My ideal position is the center of the tower, but I can't set that position.

these are my settings, but I'm still in many troubles....

(3d printer dual extruder travelling together).

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

FYI:

There is an option in Cura to change the support interface material; you don't need to change material partway through your print.

 

However making only the support interface out of PVA is not such a good idea because PVA generally doesn't stick well to build materials and printing a PVA interface on top of pla support infill will generally lead to print failures.

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

thank you @bagel-orb for your reply, and thank you @FalmouthLouis for sharing your experiences.

 

sorry @bagel-orb, but I don't understand what option you are talking about, 

 

I have really problems to print with PVA and there is not many information on the internet. You can find some tutorials in youtube but all of them are "wonderful", even the 3d printing nerd has a video but the part breaks when removing the support material, and it wasn't a small feature of the part, it was the main body. I think it was a layer adhesion problem, during a tool change (he says it was a layer shift). I don't  know, anyway this is just my humble opinion.
 

Even, I don't know the impact of settings like "Extrusion cool down speed modifier", set by default at 0.7 ºC7s. Is it really important in regards of using PVA?

The example I explained is PETG-PVA. Those are settings with the lowest failure rate for me.

 

I'm honestly appeal for people to share their settings for DUAL EXTRUSION. I know values depend on every printer, but maybe they could give me some idea, altenative point of view... help.

 

I'm sorry if I look upset, but that is my real feeling when I need to print a soluble filament (PVA) and it should be easy, similar to PLA.

 

One of my biggest problems are the material stuck in the ("cold") nozzle. As the printing time is running this quantity is increased and it will fall sometime in the coming minutes. But If the nozzle were clean, it doesn't happen.

 

Even with the optimal dual extrusion settings, the printer is oozing, specially in the first minute after tool change, so what could be a solution for me? I think a periodic cleaning of the nozzle. The Prime Tower could be used as a cleaner, I don't need a huge Shield to protect the part. The nozzle could be set to go to Prime tower every x seconds during 1 minute (for example).

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

I am talking about the option Support Interface Extruder. The support interface is the portion of support just below the overhang (and just above the model if the support is resting on the model).

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

thank you for your quick reply @bagel-orb,

 

I think what you're saying is what I'm using... I use to use the support configuration depending on the geometry of the model. 

Having a look at @FalmouthLouis handle picture, it is the same for me, when I show a 3d printed part to a "3d printing foreigner" the part is always compare with injection moulding, and even I explain it is different approach, that should be one of our goals to spread and normalize the technology. That is why I think dual extrusion should be a battle horse to push the spreading. 

 

 

capt_support_settings_extruder.JPG

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

I'll come back to this debate later on today, as I am having to tackle a severe PVA problem. I'm trying to print a copy of someone's sculpture, which needs PVA support because Breakaway would produce too much strain on the structure when I tried to remove it. Initially, PVA flowed for about an hour but then seized up in the nozzle. I've three times done hot/cold pulls and got the PVA apparently flowing, but, as soon as I try starting the print, nothing flows again. This is despite the fact that I'm using all the tricks I know to dry the PVA.

 

It could be that the problem is the extremely damp weather we've been having. I print in the part oif a workshop which is only partially heated, so the air will have been pretty moist over the last two or three days.

 

Anyway, I'm going back to the workshop to see what I can achieve today.

 

Incidentally, I am working with an Ultimaker 3 Extended, and I just use Cura settings for Ultimaker's PVA.

 

I'll report back.

IMG_5077.jpg

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

To what extent can one rejuvenate old or moist PVA?

 

I've got four or five partial reels of PVA floating round my workshop, some of which will be 18 months old.

 

Does anyone know how PVA ages if it's kept in reasonably dry conditions?

 

Secondly, if PVA is just kept in a cupboard with no dessicants, how much does it deteriorate? I have a fruit dessicator, so I can heat the reels up without any problem. I saw somewhere that you should not heat PVA above 40 degrees. Does anyone have views on that? To what extent can one use heating/drying to rejuvenate elderly PVA?

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

Hi @FalmouthLouis and thank you for keeping this thread.

 

I keep the PVA spool in a plastic box with silica balls, and when I need this material I leave it for 24-48 h in the  fruit dehydrator, and then I print PVA from there. 


Conditions: 55ºC. 40-45% moisture. (it can't be better. I live in a rainy place). These are the parameters in probe, not in the dehydrator knob.

 

Also a member with relevant experience in dual extrusion is @amagro, participating in several related threads. 

 

@FalmouthLouis could you please share the settings you are using, I'm talking about retractions, speeds, temperatures...

 

numbers, numbers, numbers...

 

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

I might be a little late to the party but we print all our models with PVA supports, mostly demo parts of thin 0.7mm grilles.

 

I have never had problems with it clogging but it is stored in boxes similar to these: 

https://richrap.blogspot.com/2018/02/diy-heated-drybox-for-3d-printing.html

 

The only difference is instead of sealing the box the heater is placed underneath it, the bottom then filled with desiccant beads and the spools placed on top. I don't close the lid but just place it on top. This keeps my spools at around 25% humidity and I have no problems printing. I should add that the room we print in is kept at 18C.

 

Previously it was kept in a cool warehouse and we would have to repeatedly dry it.

 

If I hear any popping ( a sign of moisture in the filament) usually caused because it's been on the machine too long, I pop it in a halogen oven for 2 hours at 60C. Drys up and prints great.

 https://www.hartsofstur.com/judge-halogen-oven.html?kk=a4c6224-170ed1ff0d9-78908&gclid=EAIaIQobChMI077dpOSj6AIVQ7DtCh1fOgC6EAQYBCABEgK7hPD_BwE&utm_source=kelkoouk&utm_medium=cpc&utm_campaign=kelkooclick&utm_term=Judge+JEA30+Halogen+Oven

 

I haven't found it ever prints particularly pretty. But the quality of the actual print is often very good.

 

 

 

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

thank you @VT3D for sharing your experiences with us ("dualers").

 

Could you share some of your settings? Retraction values? Temperatures start/end/standby? speeds? resting position?

 

thank you in advance.

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

I can but I'm not sure they're particularly different from the recommended. 

 

I start at 200C, printing at 215C though I intend to do some single wall columns to optimise this.

 

Standby is the given 100C. 

 

I played with the retraction settings but eventually returned to 5mm.

 

I'm afraid I don't know what you mean by resting position?

 

 

 

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Posted · Optimising support structures: Central repository for advice: PVA, Breakaway

thank you @VT3D for your reply sharing your settings.

 

resting position, the place where nozzle switch hapens. Is there any especific XY coordinates? or just in the middle of the part

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