MMU2S and Prima Select PVA+: Anybody having success?

MMU2S and Prima Select PVA+: Anybody having success?  

Estimable Member

I have never been able to make Prima Select PVA+ dissolvable filament work with my Prusa MMU2.

The prima select filament  is 1.75mm on the spool. The MMU2 can feed it to the hot end just fine. But when it retracts the hard blob on the end is 2mm or larger. As a result, the motor cannot retract it. It's a very difficult pull by hand.

So I have never been able to have a successful filament exchange using the MMU2 and PVA+. It fails 100% of the time.

Is there an answer to this? Are others having this problem?



Yes, the PVA checkbox is set in Prusa Slicer for this filament type.


This topic was modified 1 year ago by SeattleDavid
Posted : 14/03/2020 2:58 am
Trusted Member

I use Primaselect PVA+ all the time and it works very well for me.  I never have MMU2S errors with it.  Are you using the default profile for it?

When using soluble filament I think it is important to have a filament dryer.  I would try using the filament right after drying it and see if you have the same problems.  You might find that solves all your issues.  I got this and modified it to work for filament:



Posted : 08/05/2020 12:36 am
Estimable Member

When I first ordered the MMU2, I was convinced that I would be able to print complex objetcs with soluble support material.

The reality is quiet different, if in fact we can manage to print PVA with the MMU2, the biggest downside is the impact on the printed part inter-layer adhesion, it's nearly impossible to avoid the PVA to not contaminate the part you are printing and weaken it.

My conclusion is, if you print objects like figurines or decoratives objects, yes the MMU2 can do the job, but if you want to print functional objects that require strenth, the MMU2 is not the answer, without having tested, in my opinion a dual extruder printer would be more appropriate.

I definitely gave up with soluble support material.

This post was modified 1 year ago by ad.lamy
Posted : 08/05/2020 9:42 am
Trusted Member


I have not had this problem with layer contamination (at least I don't think so).

Here's an example of an object which I wouldn't have been able to make without the MMU2 with soluble (at least not without glue!):

This was printed in place as a single object with soluble interface.

Since this photo I've improved the print quality.  E.g., here you can tell the difference between the quality of the top and bottom of the arrow, but now you can't. (The trick was adding a thin solid arrow of soluble support material to the object, directly underneath the purple arrow).

Posted : 08/05/2020 3:09 pm
Estimable Member


I agree with you, but like I said in my previous post this particular problem occurs only when the part you print is supposed to bear an effort.

Unfortunatly in FFF printing the part you print is never stronger as the weakest layer.


Posted : 09/05/2020 9:23 am
New Member

I do not know if this thread is still being watched but I have a question. Can someone advise the setting in prusa slicer to allow the mmu2s to use the soluble pva+ as the supports ?  I just dont find how I make the selection to choose that spool ,  sorry if this is a stupid question

Posted : 18/09/2020 4:54 pm
Prominent Member


not sure if you figured this out but there's a profile in prusa slicer for it.  I've had limited success with.  Like other's I've had it create blobs that are very difficult to pull back out of the PTFE tube.  I ordered this particular pva because it's what prusa sells on their website and I was hoping for better results with it.   When it does work it's great.  But the "does work" doesn't happen enough in my opinion.  Yanking the filament back out of the extruder through a very thin tube that just barely fits the filament seems like a flawed design.  Something along the lines of the Palette seems like a better approach since the extruder only ever sees one steady stream of filament.

I think in general the MMU is very hit or miss.

Posted : 28/03/2021 8:33 pm

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