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foehnsturm

Any experiences with dual extrusion and PVA?

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Posted · Any experiences with dual extrusion and PVA?

Yep, the raised temperature did the trick.

The crossflow is still mounted in the UMO, which I don't use atm.

The tube is printed with approx. 40% fan (stock UM2+ fans)

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Posted (edited) · Any experiences with dual extrusion and PVA?

So now I almost know what settings PVA likes. Unfortunately it's a combination Cura doesn't

offer yet. I prefer zig-zag infill because other patterns seems to produce a heap of retractions. However, with zig-zag there is no perimeter line around the infill and without that perimeter support roof produces a mess as 50-90% of the lines start in mid-air. You can see the difference between zig-zag support without roof and grid support with support roof  on the two pictures showing the bottom side.

BTW: Why these sharp corners with zig-zag infill (every slicer seems to do that)? If PVA de-laminates it's always there, presumably due to the velocity / extrusion rate changes.

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Posted · Any experiences with dual extrusion and PVA?

P1090626.thumb.JPG.d68d71f18ddac109581647c85e19bf32.JPG

 

Oh seems you changed the glass to leave area for the priming? Nice. And by the position of the clips it seems like 1mm taller... Sorry I been trying to see something different on your photos and this it's the first time I see something different than the standard um2 :D

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Posted · Any experiences with dual extrusion and PVA?

:)

Indeed, but the original glass plate works as well.

The glass is the same thickness.

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Posted (edited) · Any experiences with dual extrusion and PVA?

Very interesting finding foehnsturm!

I'm also trying to tune in my PVA settings, can I ask a few questions?

That dark grey filament is your PVA? Interesting, mine is translucent (formfutura).

Also, how did you manage to not have the PVA ooze? Mine is oozing like crazy, no matter how much retraction i use. In fact so much that i end up with the shadow version of my print, next to it, only made of PVA :). And lastly, how soft is your pva filament on the roll? Mine is super soft, almost like a rubber, even though it was always kept dry. Even on my printer its fed from a sealed box full of silica.

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Posted · Any experiences with dual extrusion and PVA?

@foehnsturm, might it be possible that you post a complete setting list of cura2?

I´m doing some tests with PVA at my UMO too but currently have a lot of troubles finding the correct settings.

Acc. to my impression, separate material settings applicable for support structure are missing, so print temperature for support, separate standby temp, diameter, flow, retract e.g. asr difficult to set.

Your expertise is appreciated :-)

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Posted · Any experiences with dual extrusion and PVA?

I'm also considering one of these materials for support:

-PCL, I suppose If I put the print in hot water the supports become moldable and separate

https://www.3d4makers.com/products/pcl-filament?variant=10892826756

-This one I'm not sure how it's supposed to work, if it separates so easily, doesn't it mean it doesn't bond well to PLA in the first place?

http://www.polymaker.com/shop/polysupport/

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Posted (edited) · Any experiences with dual extrusion and PVA?

Well, I'm on holidays so apologies for the brief reply.

It's (grey) Scaffold, the E3D PVA (EDIT: PVA not PLA) variant. Yes it oozes, but as I'm using the tool changer that's no problem. Temp and retract are set via firmware. More next week .... ;)

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Posted · Any experiences with dual extrusion and PVA?

that's some crazy sh**! :)

i wonder if it wouldn't be easy to drill a simple blocker/valve into the nozzle to stop the flow and skip all the retraction silliness.

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Posted · Any experiences with dual extrusion and PVA?

@foehnsturm, might it be possible that you post a complete setting list of cura2?

I´m doing some tests with PVA at my UMO too but currently have a lot of troubles finding the correct settings.

Acc. to my impression, separate material settings applicable for support structure are missing, so print temperature for support, separate standby temp, diameter, flow, retract e.g. asr difficult to set.

Your expertise is appreciated :-)

 

Unfortunately I don't have a complete setting list at hand. It was too much experimenting (and continuous documentation is not one of my strenghts ...)

As far as I can remember: 0.15 mm layer, PVA speed (20-30 mm/s), no fan, PVA (Scaffold) temp on the upper end 215°C to improve adhesion to PLA, support z-distance 0.0.

I used join distance and horizontal expanson to connect support islands to one large structure if possible.

And please note, I gave up on standard PVA after a few hours. Scaffold still is not that easy to print but considerably easier than regular PVA.

If I find the time I'll do another test within the next two weeks.

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Posted · Any experiences with dual extrusion and PVA?

Hi foehnsturm,

You started your post with that you finally got your PVA to stick. What is the trick to that? Ever since the beginning on my UM3 I'm having the problem with getting it to stick to the buildplate. I've tried the Uhu glue stick, 3D lack (sort of hairspray), making the water disolved PVA mixture, printing slower and slower. The one thing I need to double check is the bed levelling, I kind thought it was a bit on the high side which could make the adhesion problematic.

What also strikes me as odd is the priming of the PVA extruder at the start. For the non PVA prints coming from either the left of right extruder, the speed and behaviour seems to be exactly the same, for PVA it starts (you hear the motor and see the PVA advancing in the tube but nothing extrudes, then finally it comes out.

Now the normal sequence is, start extruding, after 2 secs you got the big bulb, buildplate lowers a bit while still extruding, another 2 secs and the head moves and the extruding stops and the buildplate rises again to start the print.

For PVA, first it takes way longer than 3-4 seconds before something extrudes, then it just keeps extruding until this 3-4 times bigger bulb, then the plate lowers much slower than normal, extruding again takes at least twice longer before it stops and moves the head for the first layer. I've had a few times it just pulls that big bulb along to the start point of the first layer. (as it doesn't stick to the plate and has completely encompased the extruder)

All that on a stock UM3, with stock UM PVA, with stock settings (and with tinkered settings)

Below a pic of my last attempt, as you can see, total chaos.

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5a33288072909_2017-03-2016_56_07.thumb.jpg.a30ce05e24a653935c7034241c8a0a61.jpg

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Posted · Any experiences with dual extrusion and PVA?

I have had no real issues with printing with PVA on my UM3+. I have only used Matterhackers PVA and Ultimaker PVA and still quite the noob. But so far I have found my PVA works as expected (Well, as I expected) and I have also played with temps to try and cook it a bit or less to find ways to make it work. Most surfaces have no more issues in cleanliness where the PVA is and the general printer resolution used.

My first PLA/PVA print printed flawlessly (second print ever). Or, I have lower expectations due to what I have received from external printing sources. That is one reason I am investing in my own equipment. I am baffled by the lack of quality from some of the sources I have used compared to what I am getting with my short time on the machine.

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Posted · Any experiences with dual extrusion and PVA?

 

@rhoogenboom - the trick is to usually to squish the PVA more into the glass. I'm thinking you didn't calibrate your Z offset properly between the nozzles and your pva nozzle is higher above the glass when printing than the other nozzle.

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Posted · Any experiences with dual extrusion and PVA?

ORLY? It likes to be super-squished, or you're just saying it is sensitive to barely touching?

 

I've probably never had an adhesion issue that ultimately wasn't level and first layer squishing.

 

As someone about to build their own dual-extruder set up for a CR-10.... any advice? I guess bowden isn't an issue?

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