UM PVA snapping in bowden tubes

[aoeng 1]

Greetings All,

 

I've had the UM PVA snap in the bowden tubes as the filament enters the coupler (the rectangular thing on the back of the material station inline with the bowden tube) a few times. I've been able to recover, but would rather not have to go through that process too often. I've seen a few posts about this, but not much by the way of fixes.

 

In both my failures they occured in the morning after the printer had been off overnight - material station is left on.

I am wondering what the working temperature of the PVA is? I know storage is between 0c and 30c. I am guessing that the temperature in the room is somewhere between 0c and 5c in the morning if everything has been turned off. Don't have thermometer, just going by the outside temperature.

How brittle does PVA become as it gets cold?

Are there other things that can effect the PVAs mechancial properties that would make it more likely to snap?

Also, the snaps occured at 50cm and 53cm from the end of the filament as it was being sent from the material station. Maybe that's helpful to know.

 

Thanks,

Robbo

 

[ccmaker2020 2]

I had this problem as well and I ended up using the breakaway material due to it getting caught. I hardly use the PVA now. (Using a s5 pro bundle)

[willryan3 4]

PVA actually becomes more brittle upon water absorption. Try drying it out and keeping it dry when you are not using it.

[ccmaker2020 2]

"Ultimaker S5 with its custom-engineered Material Station and Air Manager, now you can transform your office 3D printing workflow with automated material handling, optimized air filtration, and filament humidity control." 

The purpose of the purchasing the S5 pro bundle was that this system integrated a filament humidity control. Maybe the pva that came with it was compromised? However the case, the room in which this sets on, does not receive humidity and with the added humidity control on the system in itself I figure the pva would not brittle. I ended up tucking away the pva filament and using the breakaway.

[willryan3 4]

38 minutes ago, ccmaker2020 said:

"Ultimaker S5 with its custom-engineered Material Station and Air Manager, now you can transform your office 3D printing workflow with automated material handling, optimized air filtration, and filament humidity control." 

The purpose of the purchasing the S5 pro bundle was that this system integrated a filament humidity control. Maybe the pva that came with it was compromised? However the case, the room in which this sets on, does not receive humidity and with the added humidity control on the system in itself I figure the pva would not brittle. I ended up tucking away the pva filament and using the breakaway.

I am in the same boat. I had a lot of trouble with the PVA and switched back.

[aoeng 1]

I've notived that the PVA becomes noticably more ductile as it warms up.

 

With that in mind, the last couple of prints I've put the spool on the print bed at 30C for an hour or so. Both prints has succeed, but a sample size of two is not exactly data... I've looked through the material station doco, it makes not mention of temperature control. So I assume it doesn't.

 

Taking the spool out also gave me a chance to check the filament tip and sharpen it up. Sometimes it comes out of the extruder after depriming quite blunt, which has caused me issues in the past.

 

 

[aoeng 1]

8 hours ago, willryan3 said:

PVA actually becomes more brittle upon water absorption. Try drying it out and keeping it dry when you are not using it.

My PVA lives in the material station. Material station doesn't get turned off  - except when I am pulling PVA fragments out of the tubes 🤪. But the material station should be taking care of the moisture problem, so I don't think that's an issue. Though I have no way of testing humidity.

[AndersK 59]

I dont know the moisture limits for UM PVA, or if this is the only reason, but if stored in a room with 30% humidity a longer time it will break in the bowden.

This is from my own experience.

 

I would be worried about temperature cycling for the equipment though. That cold in the mornings would likely cause condensation

Edited May 14, 2020 by AndersK

[SandervG 1,521]

23 hours ago, ccmaker2020 said:

"Ultimaker S5 with its custom-engineered Material Station and Air Manager, now you can transform your office 3D printing workflow with automated material handling, optimized air filtration, and filament humidity control." 

The purpose of the purchasing the S5 pro bundle was that this system integrated a filament humidity control. Maybe the pva that came with it was compromised? However the case, the room in which this sets on, does not receive humidity and with the added humidity control on the system in itself I figure the pva would not brittle. I ended up tucking away the pva filament and using the breakaway.

 

Hi, it indeed has humidity control but an important nuance to make is that the material station is capable of keeping your PVA dry, but its purpose or capacity doesn't cover making it dry. So it is always recommended to dry your filament before loading it in the material station to ensure it is dry. Hope this helps!