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markus_oswald

PVA not sticking on glass

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Hi,

i try to print with PVA as support, but its not sticking on the glass.

What's wrong with the printer... so far i only have problems.... nothing really work...

- cracked sliding blocks

- auto level problems... but solved :)

- pva support is not working...

Markus

IMG_3161.thumb.jpg.f3c2f10e09b6a55dc1661350d7d0f69d.jpg

IMG_3161.thumb.jpg.f3c2f10e09b6a55dc1661350d7d0f69d.jpg

Edited by Guest

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Hey Markus,

sorry to hear about the problems. I have the same but I know they are being worked on.

PVA is particularly tricky to stick if bed leveling is not optimal. Did you use the default Cura 2.3.1 profile when slicing stuff? I think with that version a prime tower is used. If that's the case, you could increase the size of that tower (advanced settings).

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Is the glass clean when you start? What about the tip of the nozzle? If you've got filament hanging off the end it can throw off the active leveling.

 

yes, the glass is clean. active leveling works good and there is no dirt on the nozzle. the pva doesn't stick on the glass if the nozzle put a new line of pea across an existing line... so if there are only lines of pva and no crossings it works better... but sooner or later there is a crossing and the new line pulls the existing lines away

markus

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Hi Markus,

When looking at this first layer of PVA (the second extruder) it seems to be to high above the bed. I.E. it is not squeezed to the bed, I'd assume it should look a little "flatten out" looking. The skirt (PVA) looks to be "kind" of good, -so could it be something about height "now and then" different when switching head to number two?

Anyway, good luck.

Thanks.

Torgeir.

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... or apply a solution of 1/3 wood glue (is also made of PVA) and 2/3 water if you dont want to dissolve your expensive PVA :-)

 

Well, you can still re-use the PVA - after it has been printed - for this purpose, right? (ask, how I know...) :p

@markus_oswald

Additional hints regarding the original question: you can try the following:

 

  1. increase the printing temperature for PVA a bit

  2. increase the feeder tension (approx. to 70% of the max. position)

  3. increase the flow rate (try 120%)

 

All three things can be tuned during printing. You'll see the difference. +5°C and a good feeder tension worked for me. Increasing the flow is the emergency solution.

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PVA should stick to the buildplate just fine. Really. With the default profiles.

I advise against playing with the settings. The settings in the profiles have been tested very well, and perform robust if your machine is in order.

Have you had any incidents with PVA with the BB nozzle? I mean, a period where there was little or no flow, and the nozzle was hot?

PVA deteriorates quickly, and your BB print core can be partly blocked. That gives underextrusion, which hurts your first layer.

I notice that the support is printed with squares, while I think the default in all profiles is "triangles". So my guess is that you don't use the default settings.

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PVA should stick to the buildplate just fine. Really. With the default profiles.

Have you had any incidents with PVA with the BB nozzle? I mean, a period where there was little or no flow, and the nozzle was hot?

PVA deteriorates quickly, and your BB print core can be partly blocked. That gives underextrusion, which hurts your first layer.

 

Hi, I have the same problem, and I did have an "incident" with my BB core. I did several hot/cold pulls and cleaned the opening of the nozzle with fine acupuncture needles of different diameters, but the problem still persists. The first cleaning blob of the PVA always, literally always, sticks to the nozzle and messes up the print afterwards.

I am using default settings ... any suggestions would be appreciated!

best, Georg

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PVA is a water soluble support filament, more infos here : https://ultimaker.com/en/products/materials/pva

 

A glue stick is normally based on PVA (not all) and has nothing to do with the filament. If you have PVA leftoulvers from your print, then you can mix it with water and you get an emulsion which is perfect for your bed adhesion instead of the glue stick. Why? Because it is the same result if you put on the emulsion on the glass or the glue stick.

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So, Mix it very thin and just brush it on and let set? I thought I might not have the build plate hot enough at 60 degrees. White PLA seemed to work ok and Black PLA never stuck, even with the bed temp 100+ degrees.

I will let you know how it worked out. I bought a pc of Bisiliocristiline (spelling) figured it would fix the issue, not.

Thanks 

 

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I also hate waste!! but how do you recycle it? by using it as a glue? Id love to be able to recycle left over support PLA. Someone needs to make a decent reliable home extruder. Mind you PVA could be harder to extrude than PLA? Im doing my largest print ever (2 days, not that big by your standards mind you!) but 23 meters of filament and larger than my UM2 can print so have to use the S5, but Im guessing a lot of it is support. Just looking at the amount of it when I pour it into the bin afterwards upsets me.

 

 

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