Resin Leaks between tank and frame  

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gnat
 gnat
(@gnat)
Prominent Member
Posted by: @ryan-c29
Posted by: @gnat

@ryan-c29

I didn't notice when I removed them last night, but that is pretty much exactly what both my FEPs look like. Every hole except the 4 corners are elongated. Messy as it may be, it really makes me suspect that a silicone bead might be the way to go.

I'll let you be the first to test that =p I've got an email into support about this design failure. I've gone through 8 new FEPs at this point and kinda ticked off. Best success I had was by using a FEP from another company that was oversized and had no holes punched. I punched the corners first, tightened those down to stretch it over the tank, then punched the rest of the holes after stretching, no leaks from that method.

I wondered about using another FEP. I was thinking about it as a possible quality issue though.

It's pricey, but have you looked at EPAX's nFEP yet? ( https://epax3d.com/products/nfep-premium-film-for-x1-e6-printers) They have some nice sounding bullet points:

  • UV stable
  • non-stick surface for 3D resin printing
  • less vacuum suction force

I tend to take manufacturer claims with a grain of salt though and haven't had a chance to do significant research yet.

MMU tips and troubleshooting...
Posted : 30/10/2020 7:16 pm
Xulkal
(@xulkal)
Trusted Member
Posted by: @gnat
Posted by: @ryan-c29
Posted by: @gnat

@ryan-c29

I didn't notice when I removed them last night, but that is pretty much exactly what both my FEPs look like. Every hole except the 4 corners are elongated. Messy as it may be, it really makes me suspect that a silicone bead might be the way to go.

I'll let you be the first to test that =p I've got an email into support about this design failure. I've gone through 8 new FEPs at this point and kinda ticked off. Best success I had was by using a FEP from another company that was oversized and had no holes punched. I punched the corners first, tightened those down to stretch it over the tank, then punched the rest of the holes after stretching, no leaks from that method.

I wondered about using another FEP. I was thinking about it as a possible quality issue though.

It's pricey, but have you looked at EPAX's nFEP yet? ( https://epax3d.com/products/nfep-premium-film-for-x1-e6-printers) They have some nice sounding bullet points:

  • UV stable
  • non-stick surface for 3D resin printing
  • less vacuum suction force

I tend to take manufacturer claims with a grain of salt though and haven't had a chance to do significant research yet.

That's the exact "FEP" I used in my successful test. =D I plan on going back to that and using it more if it gets me unblocked and printing without leaking. The test prints I did on it before had a little higher failure rate due to sticking to the nFEP than what I was getting with the FEP, and that may have been my own fault as I was still figuring things out.

Posted : 30/10/2020 7:21 pm
gnat
 gnat
(@gnat)
Prominent Member

@ryan-c29

Interesting. Will be interested to hear more from you about the nFEP.

MMU tips and troubleshooting...
Posted : 30/10/2020 7:42 pm
vintagepc
(@vintagepc)
Noble Member

Those pictures do look like the FEP is preferring to stretch at the weakest point - screw holes - rather than from the center where it should,which seems like a flaw with this design of tensioning system.

Random engineering thoughts that might offer a solution:

I wonder if some sort of reinforcement could prevent that type of "tearing"/stretching. Kinda like those donuts you can buy to use with paper sheets in binders. 

Really what you need is a way to sandwich the FEP between two pieces of metal frame first, and *then* draw it down over the bottom of the tank to tension it evenly. That would secure it uniformly all the way around and prevent the holes from stretching. 

Or, you'd need some sort of thickened edge that offers more support at the edges so that the screw holes cannot tear out like that. 

Is the FEP the same size as the metal frame? Maybe adhesive could be used to bond the FEP to the frame to give it that pseudo-support. 

Posted : 30/10/2020 9:25 pm
Xulkal
(@xulkal)
Trusted Member
Posted by: @vintagepc

Those pictures do look like the FEP is preferring to stretch at the weakest point - screw holes - rather than from the center where it should,which seems like a flaw with this design of tensioning system.

Random engineering thoughts that might offer a solution:

I wonder if some sort of reinforcement could prevent that type of "tearing"/stretching. Kinda like those donuts you can buy to use with paper sheets in binders. 

Really what you need is a way to sandwich the FEP between two pieces of metal frame first, and *then* draw it down over the bottom of the tank to tension it evenly. That would secure it uniformly all the way around and prevent the holes from stretching. 

Or, you'd need some sort of thickened edge that offers more support at the edges so that the screw holes cannot tear out like that. 

Is the FEP the same size as the metal frame? Maybe adhesive could be used to bond the FEP to the frame to give it that pseudo-support. 

Right, exactly. The FEP and Frame perfectly line up with the holes so in theory you could use some adhesive to bond the FEP to the frame as you said, but then the problem becomes when it's time to replace the FEP due to damage, scratches, etc.

Posted : 30/10/2020 9:31 pm
vintagepc
(@vintagepc)
Noble Member

Depends on the adhesive; some are very resilient to normal conditions but can be easily removed with an appropriate solvent. (e.g. superglue vs acetone)

Though getting something to stick to the FEP might be a challenge. 

 

Posted : 30/10/2020 9:35 pm
Xulkal
(@xulkal)
Trusted Member

So I used my last nFEP in the water test now and also failure.
https://photos.app.goo.gl/S3kL6tvD7FRWwFYw7
You can see in that gallery the nFEP holes I punched were damn near perfect and unstretched. However that still wasn't good enough for a complete seal as I was still getting leaking after very short bit of time of the tank sitting on paper towels.

Pretty much I think the tank needs an o-ring groove on the bottom to ensure a proper seal.

This post was modified 4 weeks ago by Xulkal
Posted : 30/10/2020 9:40 pm
gnat
 gnat
(@gnat)
Prominent Member
Posted by: @vintagepc

Really what you need is a way to sandwich the FEP between two pieces of metal frame first, and *then* draw it down over the bottom of the tank to tension it evenly. That would secure it uniformly all the way around and prevent the holes from stretching. 

That's apparently how the Mars tanks work. I watched a video for it's FEP replacement while trying to find expected life span info for FEP in general. As I was watching it my thought was "now why didn't Prusa do it that way" even before noticing the stretch holes.

MMU tips and troubleshooting...
Posted : 30/10/2020 11:37 pm
gnat
 gnat
(@gnat)
Prominent Member
Posted by: @ryan-c29

So I used my last nFEP in the water test now and also failure.
https://photos.app.goo.gl/S3kL6tvD7FRWwFYw7
You can see in that gallery the nFEP holes I punched were damn near perfect and unstretched. However that still wasn't good enough for a complete seal as I was still getting leaking after very short bit of time of the tank sitting on paper towels.

Pretty much I think the tank needs an o-ring groove on the bottom to ensure a proper seal.

I think you are right about something besides bare metal for the seal surface. Based on those pics it looks like the stretching is not the issue. It looks like it's just not a good seal and the capillary effect is wicking the resin up and over the edge (or through the screw holes) and then down onto the LCD.

MMU tips and troubleshooting...
Posted : 30/10/2020 11:40 pm
Xulkal
(@xulkal)
Trusted Member
Posted by: @gnat
Posted by: @vintagepc

Really what you need is a way to sandwich the FEP between two pieces of metal frame first, and *then* draw it down over the bottom of the tank to tension it evenly. That would secure it uniformly all the way around and prevent the holes from stretching. 

That's apparently how the Mars tanks work. I watched a video for it's FEP replacement while trying to find expected life span info for FEP in general. As I was watching it my thought was "now why didn't Prusa do it that way" even before noticing the stretch holes.

Wow, just watched their fep replacement video and certainly looks like a much better approach. Could be done with this tank design too if area where the frame drops in is milled out more/deeper.

Posted : 30/10/2020 11:43 pm
gnat
 gnat
(@gnat)
Prominent Member

Well, glad I didn't just fill one up with resin and start printing. Stayed dry for the first few hours, but just found this (about 14 hours total) when I checked this morning 😡

Both are fresh FEPs installed Thursday night per Prusa's KB article. Neither have seen resin yet. One was installed on the printer for awhile, the other was in a bubble wrap bag laying upside down (FEP up) prior to doing this test.

Will document taking them apart later and complain at support some more...

MMU tips and troubleshooting...
Posted : 31/10/2020 4:11 pm
gnat
 gnat
(@gnat)
Prominent Member

Well there's the problem. Under magnification it is clear that the sealing surface is not remotely smooth. It's engineering 101 that to create a seal you need smooth surfaces or a gasket that can account for variations (usually you want both to be safe).

This is 100% design failure in my book. The good news is once we identify an appropriate (e.g. not going to negatively effect the FEP or resin) option, a tiny bead of sealant before laying the FEP down should solve it. I'd be ok with that on a $200 printer, I don't find that acceptable for what Prusa is charging...

MMU tips and troubleshooting...
Posted : 31/10/2020 5:38 pm
gnat
 gnat
(@gnat)
Prominent Member

Here are the disassembly pics for both tanks: https://photos.app.goo.gl/Hg5UxEyEW4dd4J1Q7

This appears to be showing the same thing that @ryan-c29 is seeing. Water is clearly under the retaining plate when it is removed and water can also be seen under the FEP in the retaining area. Note that the pics with the tissues over the tanks is showing where they picked up water on the lip of the tank after removing the FEPs.

MMU tips and troubleshooting...
Posted : 31/10/2020 6:47 pm
Xulkal
(@xulkal)
Trusted Member
Posted by: @gnat

Well there's the problem. Under magnification it is clear that the sealing surface is not remotely smooth. It's engineering 101 that to create a seal you need smooth surfaces or a gasket that can account for variations (usually you want both to be safe).

This is 100% design failure in my book. The good news is once we identify an appropriate (e.g. not going to negatively effect the FEP or resin) option, a tiny bead of sealant before laying the FEP down should solve it. I'd be ok with that on a $200 printer, I don't find that acceptable for what Prusa is charging...

In theory, the FEP should be smooth enough for a good seal, but as you pointed out the sand blasting done to this part of the tank is definitely causing a problem in forming that seal. It's now making me doubt an o-ring would help as well. As you said, a bead of sealant is probably the only viable option.

Posted : 31/10/2020 7:45 pm
Xulkal
(@xulkal)
Trusted Member

I suspect that the main reason this isn't being noticed as a wide spread issue is that cured resin is acting as that seal. The problem is going to be: how do we get that seal reliably without relying on cured resin.

Posted : 31/10/2020 7:55 pm
Michael
(@michael-19)
Eminent Member

Is your resin tank sandblasted? Mine's not and I usually get more than ten prints out of one. I've used four in four months of printing. My sealing surfaces are smooth.

Posted : 31/10/2020 8:43 pm
Xulkal
(@xulkal)
Trusted Member

@mbarr

Really? Wow. Mine is definitely sand blasted as you can see in the image, same as @gnat:

This post was modified 3 weeks ago by Xulkal
Posted : 31/10/2020 8:52 pm
gnat
 gnat
(@gnat)
Prominent Member
Posted by: @mbarr

Is your resin tank sandblasted? Mine's not and I usually get more than ten prints out of one. I've used four in four months of printing. My sealing surfaces are smooth.

I don't know if it is sand blasted or something else, but there is definitely a texture to it. The only smooth/polished areas on both my tanks are on the top around the boot holes and around the level markings.

If you can get us a picture of the lips the next time you change the FEP that would be great.

Have you not had any leaks? What is your indication that a new FEP is needed?

MMU tips and troubleshooting...
Posted : 31/10/2020 9:13 pm
Michael
(@michael-19)
Eminent Member

Sorry, I meant to say I've used four FEPs in four months of printing, not four resin tanks.

I emptied the resin tank so I could turn it over and take this photo. I'm not removing the FEP for this photo, because I don't want to wreck the FEP. In this photo the resin tank looks like its been sandblasted, although I thought it was smooth, and I should also point out that I've previously run my scraper over it a few times, so this is really not a conclusive photo. Next time I replace the FEP I'll take a photo and paste it here (if I remember)

This post was modified 3 weeks ago by Michael
Posted : 31/10/2020 9:25 pm
Xulkal
(@xulkal)
Trusted Member

Ok ya, that is definitely sand blasted. I guess you are just getting a better seal than we are.

Posted : 31/10/2020 9:30 pm
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