RE: Resin Leaks between tank and frame
Then in the second image highlighted in green are the dry spots under the FEP, the remainder was wet with resin in the corner.
This is the part that wasn't clear to me. Thanks. The resin accumulated at the bottom of the lip in those images looks almost like the o-ring which is why I was a bit confused.
So it wasn't an insignificant level of resin, which is why I lean towards even a factory installed FEP being unreliable at best with resin even though this single test didn't fail.
Given what you are showing I would argue that it did clearly fail and in a not at all unreasonable scenario (start a long print early in the day, but can't get back to it until the next morning). That it didn't actually drip out is, to me, irrelevant as I don't think it could be reasonably argued that it was not going to happen pretty soon.
Bottom line to me is that an o-ring is a very cheap and reliable way to ensure the tank is leak free and that Prusa should update their stock and installation guides to include o-rings. This will only improve reliability and reduce the risk of tank failures at very little cost.
I agree. If your o-ring pans out I'll definitely be going that route. The rubber band clearly appears to be working, but I prefer using things for their designed purpose in situations like this 😉
Once I know and have my own metrics I'll be pushing it on Prusa too. It will save them from having to do a tank redesign, it's easy to retrofit for those of us having the issue, and it's easy to deal with (unlike sealer).
RE: Resin Leaks between tank and frame
The only thing to worry about is long term stability of the O-rings under UV exposure and in contact with the resin.
They may just break down without impact, but some rubber compounds can turn to goo and leach, which could lead to no visible degradation but an impact on the strength/quality of the final part.
Likely one could find a chemical compatibility data sheet for the o-ring material to see what sort of things degrade it and/or determine whether the resin falls in one of those.
RE: Resin Leaks between tank and frame
@vintagepc
Resin is certainly a consideration, though that is an upside to buying real o-rings vs using rubber bands (you can get the spec sheets that tell you what it is safe for).
The UV I'm not so worried about as it's placement is beyond the LCD panel and even if you were doing a 100% layer that doesn't actually use the entire panel from what I can tell. I expect there will be a bit of light transmission via the FEP itself, but it should be a small enough amount that I wouldn't be concerned about it.
RE: Resin Leaks between tank and frame
@vintagepc
The o-rings I linked are Buna-N ( https://en.wikipedia.org/wiki/Nitrile_rubber), which is decent for it's chemical resistance. However UV could be a problem. That being said, since the o-ring is on the outside lip, it won't be expose to the UV light from the LCD as it is projected by the lip on the LCD panel, the frame, and tank lip as well. So I'm not concerned about the UV stability in this case.
Edit: O-Ring still going strong on the water test.
RE: Resin Leaks between tank and frame
@vintagepc
Stupid edit timer...
In Step 4 of the pre-flight checks you can see how some of the LCD frame is visible through the bottom of the tank. Further in Step 6 you can see how much of the LCD doesn't get used. So I'm confident that the o-ring would be safe from direct/intense UV exposure.
RE: Resin Leaks between tank and frame
Why not go all the way and torque the bolts progressively.
RE: Resin Leaks between tank and frame
@bayes7m
The torque on the bolts is not the issue. It is the rough surface on the sealing areas that do not let the FEP create an effective seal.
RE: Resin Leaks between tank and frame
My theory is that over time the holes in the FEP rip open more and more since there is quite a lot off stress on the FEP, eventually causing leaks.
When I open a tank after it leaked, the FEP holes got pretty long.
RE: Resin Leaks between tank and frame
20h+ on the o-ring test with no leaks or indication of leaking. I decided to call the test early and disassemble the tank to see the results.
https://photos.app.goo.gl/QL8rc6CjGn5yRPha9
The photos of the tank after the frame is removed paint a crystal clear picture, o-rings work. The area where the frame sat was bone dry, with no indication of any amount of water going past the o-ring. Inspection of the o-ring also turns up that it fairs extremely well and not deformed at all and will withstand much longer periods of time being installed before it will possibly fail.
I think the results speak for themselves.
RE: Resin Leaks between tank and frame
Which diameter o ring are you using?
RE: Resin Leaks between tank and frame
Which diameter o ring are you using?
https://www.mcmaster.com/1302N101/
100 mm ID, 1 mm wide (102 mm OD)
RE: Resin Leaks between tank and frame
@piranhamousemods
Most of that stretching is happening during the actual install, though I'm sure there is indeed more that happens as the FEP tries to return to it's relaxed state.
The stretching also isn't directly the source of the leaking issue, the larger hole just give it a closer/bigger place to slip through. A lot depends on the path the liquid takes. In some of my examples I saw it bypass the screw holes and work itself to the edge and over.
RE: Resin Leaks between tank and frame
@ryan-c29
Awesome news. Thanks.
I too think I am going to call my rubber band test early as it has already crushed every other test except for the silicone.
What I can't decide is if I want to waste what appears to be a great seal just to confirm the no leak state or dump resin in it and start spitting out prints again...
Definitely ordering some o-rings right now though.
RE: Resin Leaks between tank and frame
Final thoughts, when I was reinstalling the FEPs on both tanks, I was just thinking about the results between the two and honestly, just having that water tight seal is more reassuring and easier to clean up when it comes to FEP replacement time. It might be a small thing to most, but honestly it's just nice to have less to clean, and a clear indicator that it was reliable. So I'm updating my verdict of the factory tank & fep from inconclusive to failure.
RE: Resin Leaks between tank and frame
Ugh. I know Joseph pays some attention to Reddit. I really need to write up the "Why I will no longer recommend Prusa products to anyone" post that I've been thinking about...
Here is part of the latest (and I expect last) response from support. My response was ... pointed ..., but I let them off the hook for continuing to deal with me since we appear to have figured this out ourselves and I don't expect them to actually do anything more 🙁
It is normal to have some leaking from the Resin while printing this can't be avoid but unlike water this will take longer. The tank is not water tight and there's no rubber sealing between the frame and the foil the only thing that is keeping this in place and tight is the Tank frame that you screw in.This is why we recommend in our Manual to Remove the Resin from the Tank after each print. Also it can happen that even after 1 print you might need to change the foil and to do this, to check if the FEP foil is still good to be used you will need to remove the Resin from the VAT tank. The FEP foil as a life time of 1-10 prints, not more than that.
RE: Resin Leaks between tank and frame
@gnat
That's just down right a sad. No, it's not normal to have "some" leaking of a chemical substance, especially when said substance clearly states to wear proper protective equipment. That is not a feature that is by design, that is a flat out failure, and to state in any way this is "normal" or "expected" is down right disgusting.
RE: Resin Leaks between tank and frame
At 60 hours the rubber band test was still showing no sign of leaking. I'm tempting fate as I opted to not waste what appears to be a good seal, but after emptying and drying I filled it with resin and the printer is printing for the first time in 2 weeks or so.
RE: Resin Leaks between tank and frame
9 hours later and I just started print number 2. I didn't empty like Prusa wants, but I did lift it off the printer and did not see and indication of an issue. Will continue like this for a bit and see how it goes.
I should have my o-rings on Monday. I'll set up a tank for a water tank and when I'm satisfied I'll switch tanks so I can remove the tension plate and make sure the rubber band really worked.
RE: Resin Leaks between tank and frame
@gnat
This will be day 3 of continual printing, have to make up the nearly 2 months of time loss due to leaks somehow. Resin is continually in the tank, new fresh resin added and finger stirred. Also like you lifting the tank between prints. So far no problems or indication of such, normally by now I would see at least a little indication, so I'm feeling pretty good. I set up one tank with Prusa FEP, and the other with nFEP, currently printing on the nFEP. I don't notice much of a difference between the FEP and nFEP just yet.
RE: Resin Leaks between tank and frame
Only a 2 week back log, but yeah.
I'm printing on one of the 8 for $18 FEPs right now. Hoping that goes well as I'm disinclined to give Prusa more money right now unless I absolutely have to (e.g. replacement LCDs).