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Form 3L Issues


Yeah there’s a lot of sag on the Form 3L tanks. I have the same sag here, on both my good ones and the ones I RMA’d due to print issues. Only time it bugs me is if I want to rest the tank on a surface… with resin in it sags below the feet. I’ve been trying not to do that, or to use the carton it came in.

It’s funny, I actually found it easier to clean out all the resin from a 3L tank than the Form 3 ones. I like that it’s a simpler design with less nooks and crannies on the inside where resin can get stuck. The spout on one end is a winner. I did get some messy overflow the first time I did it… I think the trick is to go slowly. I thought about building an adjustable angle bracket to hold it in the right orientation so I don’t have to.

Is that Tough 2000 you’re printing in? I’d be happy to run a print for you and courier it down if you want to compare.

I’m not sure I’ve noticed the film deformation you’re seeing - I’ll have to take a closer look next time it’s open. I do recall a bit of waviness along the edges.


I’ve used Rigid 10k on my 3L very successfully, and there’s a good chance you can use it instead of High Temp.

Rigid 10k has an HDT of 218 (vs 238 for High Temp). In every other area, Rigid 10k is better than High Temp; see the bottom of this page to see how they compare.

The main thing about Rigid 10k is that to get the higher HDT of 218 C, there’s an additional post-cure step but other than that I think it is an easier material to work with than High Temp.


Yeah I noticed that too - definitely does not clear a table when put down with resin in it. I’m kind of surprised this wasn’t a tested requirement during design. Same with putting more effort into designing a better spout geometry for pouring resin out. I’ve worked on an SLA printer in the past, and these two things were very specific design requirements when designing the tank.

I may be exaggerating a bit on pouring out the resin. It wasn’t catastrophic - but just generally poor and more disappointed at the lack of attention to detail.

That particular print was in Draft V2, but I’m going through qualification of various different materials right now (Clear, Tough 2000, Draft, Black, Flexible 80A). Might take you up on your offer if your Tough 2000 tank is working perfectly for you.

Here’s what I noticed on my Clear tank after the first print. These Clear parts seemed OK.

Here’s a brand new tank.

I’m in a habit of always checking the underside of my tanks for my Form 3, so I noticed this right away. I’d be curious to hear from others what the underside of their tank looks like when they pull it out of their machine.

Interestingly, out of the 3 prints I’ve done - whether it’s tank related or not - there seems to be increasingly misaligned layer lines the taller your part gets. I know this is the same with the Form 3 since the taller your part, the more deflection there is, but the 3L seems to handle it worse from what I’ve seen so far.


Rigid 10K actually has slightly poorer impact resistance than High Temp and is more expensive. But otherwise agree that it is a better material generally if you need stiffness.


OK I think I understand what you mean now by deformation of the outer flexible plastic. I just checked my Tough 2000 tank and it does not have that - the edge of the outer sheet is a clean line all the way through:

Here are some images of the topside:

I do have some apparent waviness along the bond seam of the inside of the tank. I think those were always there, and don’t believe they’ve interfered with my prints. I can check some other tanks the next time I have them out.

I need to grow another arm to deal with the Form 3L tanks - not easy to hold it and take pictures (or other work) at the same time ;-).


I see similar “waviness” from the top too. I see waviness on some Form 3 tanks and they don’t seem to cause any issues.

Interesting to see how nice your bottom film looks. Have you done lots of printing with it? Almost all my tanks have some sort of deformation on that secondary film.

Formlabs got back to me and said that the deformation on the secondary film isn’t a concern and that the main failure mode is “invisible” to the eye.

That would somewhat match the success I see on Clear parts even though the secondary film is deformed…I’ll keep an eye on it though.

And agree - taking pictures of the bottom of the 3L tanks is a PITA haha.


Not sure about the causes of misalignment due to overall height. In a previous iteration of the firmware I had a layer shift mid-way through a print, around layer 900, but not since then. I’ve had success with parts up to layer 2993 (0.7 mm to spare!) and general print up to around layer 2500 with little deflection. I’m not sure why.

Here’s a photo of the “top corner” (up to layer 2513) of a part as it was printed (rotated as closely as I could to its print orientation). The vertical line you see in the upper-right is the laser seam line (it’s very visible due to strong back-lighting, but in reality its an offset of about 0.1mm, which for my purposes doesn’t matter). That’s in Tough 2000 and untreated (except for washed and cured). (Please overlook my ham-handed 3D modeling.)


After a test of Black resin I didn’t encounter the issues BILLUCAS had nor the ones I had with the White resin.
It printed fine and it was easy to remove from the build plate.

My guess is that everything works for all acceptable resins except for some random variables that make it fail.
I suspect mostly the tanks are the main reason for failure because when it doesn’t work once it fails consecutively but I’m not sure, obviously.
I tried looking at a tank that fails and comparing it to one that doesn’t and honestly I can’t see any visible difference anywhere so, if that’s the case, then it’s something imperceptible, at least to my eyes.


That matches what support had told me, that the failure cause isn’t visible


I have the same sag on my Form 3L tanks. It’s a flexible sheet and it must be normal in this case? It’s variable between tanks because of the differents density on each resins I guess. I can’t see either any visible defect on the membrane itself too. The tanks, for now, are not “wavi”. Just to confirm from my side.
Good to know that Eks had no trouble with black resin. Happy also to see that most of the type of resins seems to work properly too, specially the Rigid 10k. Like I said in a previous post; we are waiting for a V2 resin tank version, I suppose. As we can see on the Form 3.
This is still interesting to know what is going on for other users of the 3L by writing here our own experimentations. Thank you all for that!


Forgot to mention that I also have the same sag in all 6 tanks I tried so I assume it’s normal especially due to the large area it has.
They also have irregularities in the resin area’s border as a photo that was posted here.


I agree with Billucas…great to have this feedback from all us 3L users.

I have been speaking with support the last few days about a lot of these issues. I have sent them multiple print files to see if they can replicate the issues i’ve seen in my prints. I have spoken to one of the engineers about this issues and most of the time i get the “that’s odd” comment when one of my prints fail.

They do have some serious issues with this machine but it does function. One thing i noticed since the last firmware update that the seamline on my is not very apparent anymore. When i did the optics test that Billucas sent me i can’t see the line at all. I also guess i have to get a better handle on how to orient the prints on the 3L since it’s completely different than the 2. I am so used to angle my parts to build off themselves that i forget the 3 is a different technology all together.

If you look at this print it printed fine but there is layer line in the upper right corner that formlabs has yet to explain. If you also look to the left of the circle there is even stronger layer lines that are not supposed to be there. This print of course is angled like i would have done on the form 2. If i print this at a 45 degree angle where it is completely horizontal the lines go away. Weird.

Although they look deeper than they really are. The circled lines i sanded out very easily and you cannot see them anymore but the ones to the left are not as easy. Looks like i modeled them in but not supposed to be there. This was also printed towards the front side of the printer so was not set on the seamline.


Interesting, thanks everyone for their updates on their tank films. Guess there really is no visual que on a good vs bad tank.

@Titon - I’ve also seen something similar on the Clear parts that I printed (which turned out successfully IMO). One of them seems to have wavy ripples at the very top, increasing with height. See pictures below.

These aren’t very noticeable unless you look super closely…however, I do expect this to be fixed at some point.


I’m now trying out Rigid 10K.
For the 3rd time in a row: new tank = a tank from 1970.
This is getting extremely annoying!


Good lord!

For those talking in this thread or anyone that has a 3L, is there anyone with a tank presently that is reading correctly?


The first 4 tanks I tried were fine, only the last 3 have this.
All were purchased at the same, though.


I’ve used 3 tanks, they all read correctly. One of them had the issue that yields warped prints but Formlabs replaced it and the new one’s worked great.


I’ve had 2 tanks so far with the 18748 days used issue. Not a huge deal for me, but doesn’t instill confidence in the QC process of these tanks.

I ran another test of these tall, thin parts on a new tank and they have the same failure mode as before. Images in link below. All in Draft V2.

For a sanity check, I ran the same part, but cut in half on the Form 3 with no issues. For those who have been having issues that were solved by tank changes, I have some questions:

  • How many tank swaps were required?
  • What did your failures look like?


Here’s what mine looked like:

Similar to what other(s) reported, the part over the rear LPU came out ok, the one over the front one was warped. The first replacement tank fixed it and it’s coming out on my 3L great now. Once they looked at the photos, Support was pretty quick to identify the problem and send a new tank.

They wanted the bad tank back for analysis and I threw the junk part in with it.


Whoa those failures look pretty intense haha.

Interesting. I’m not seeing any discrepancies across rear or front LPU. They’re both exhibiting extreme layer banding even early on in the model that the Form 3 doesn’t exhibit.

I know these parts are probably tough, as they are tall and thin cantilevers, but I would expect the quality to be similar to the F3 at least until it gets to the very tip where more deflection would happen.

I’m currently running tests on black, clear, tough 2000 and flexible, so I’ll update on how other models come out.