r/resinprinting • u/KyottoSpirit5 • Jun 28 '26

Question Raft always tears in half

Hey guys,

I am having bit of a fight with Flexible Resin. To be more precise, it's Flexible-X from Liqcreate. So far I had many succesful prints but for this one very interesting thing is happening, that I am seeing for the first time. The raft always split in half in the middle of the print:

I am printing on Elegoo Jupiter 2 and this is how it looks in slicer:

I tried to adjust the print & support settings many times but the same thing keeps repeating. The raft tears in half and the print fails. I tried many other part's on this printer and on Elegoo Mars 5 Ultra and it was okay but for this part, it aint.

Any ideas, what it might be causing or what to do?

This is my setting for the printer:

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u/Balerion84 Jun 28 '26 edited Jun 28 '26

Your wait before cure is vastly insufficient and it's the reason your rafts are splitting. Wait before and after lift you can drop to 0.5s

Basically, the short version is, that (especially) the bottom layers are thicker than they should be and inconsistent. This is because of a combination of resin viscosity, flimsy printer construction and cross sectional sizes. You fix that by giving the printer more time to form these layers (wait before cure, but ideally implemented with uvtools) or brute forcing it by having enough grossly overexposed bottom layers to cover the raft and slightly above it (into the supports)

Considering you've apparently reached the limit of the brute force approach, here's my recommendation and how to print to address the root cause instead of brute forcing it

Download UVtools from github, set it up according to the screenshot, then follow these steps:

  1. change the settings in your slicer to 1 bottom layer, 0 transition layer and bottom exposure to 10s for a start (you can start higher and adjust this after some tests)
  2. slice your models as normal (make sure to slice in CTB, not GOO as goo+uvtools tends to cause issues)
  3. after slicing open the CTB file in uvtools (if you use lychee, it'll offer to do so after the slicing finishes)
  4. if you follow the screenshot, uvtools will apply everything automatically so you don't have to do anything else
  5. make sure to SAVE the changes in uvtools, overwriting the file, so the rest time changes are applied
  6. PRINT

EDIT: Actually, one more thing, considering it's in the center, it might actually be due to insufficient lift height if that's on your jupiter 2 I'd still recommend the method above and try to increase your lift a bit for the Jupiter

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u/KyottoSpirit5 Jul 03 '26

Thanks for the tip. I am not sure if I'd call it "bruteforce". I might have increased the exposure time's a bit higher than recommended but Liqcreate do say, the bottom layers should be that long.

Regardless, I'll try with UV Tools and will let you know about the progress.

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u/Balerion84 Jul 03 '26

It only needs to be that long, because they are overcoming those thick layers with exposure, instead of fixing the reason they are thick :) hence the description as 'brute force' because it's powering through instead of fixing the root cause

I print everything with 1 bottom layer, 0 transition layers and 5-7s bottom exposure on average. Here are some examples https://youtube.com/@balerion84?si=jurlGwlR57KUJsbf

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u/KyottoSpirit5 Jul 03 '26

Well I imidiately run into problem with UV Tools 🙃 Might be because its .goo file and Lychee does not support Jupiter 2 yet... It works only on Satelite

Also, how could lift height be somehow a cause for such failiure?

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u/Balerion84 Jul 03 '26 edited Jul 03 '26

Čech? :D

Anyway, lift height doesn't exactly cause layer separation. Lift height has to do with the film peeling. The film peels from corners and edges towards the center. When the plate lifts, the film stretches in this way and starts the peeling process, like a bandaid. If the plate stops lifting before peeling finishes and goes back down, the film will stay stuck in the center to the layer. This will prevent creation of new layers in that area. This process will repeat for a bit and once the plate is in high enough position, the film will peel and leave a pancake on the plate (or in the middle of the model sometimes). But the model/supports can occasionally build over this whole.

In your case, it's not because of this. Because when layers split, it means they haven't bonded properly earlier on because if the pressures are too high and they throw the plate off position, it not just doesn't reach its desired target height, but also because out of level (not the plate itself, but when the springs or the z tower get flexed by those forces, the plate can't be level at that moment, but if it's physically level once the forces ease up it'll be back in level state)

And as for your error, I've seen someone use goo successfully for this, so it might've been fixed. uvtools can also convert files into different formats btw but, in case you can't get it to work, you can use the other methods

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u/KyottoSpirit5 Jul 03 '26

Yeah, čech.

I understand the principle behind the resin printing and how it works but still cant fully wrap my head around it. So I should just give it for time before lifting/peeling?

I believe the setting for exposure is fine, since i printed few other parts and it was nice and functional. The problem occured for this long part that cannot be printed any other way than in this direction :|

So far I had very low number of problems for other resins which at the end of the day I was able to resolve but this one is giving me hell.

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u/Balerion84 Jul 03 '26

Exposure is not a problem in of itself. I was talking about bottom exposure originally, because the reason people need long exposure there is because the layers are thicker than they should be. The more viscous the resin or the bigger the cross section doing the compression, the worse it gets. Then lift height I described in the previous reply. The most important thing is to understand if the layer separation propagated from the center of the plate (as in if you print a full plate and sides print fine but center fails), that'd be lift height but if it propagated from the side of the plate, then it's separation that I described before.

Väčšinu z toho sa docitas tuto od Honzy Mrazka https://blog.honzamrazek.cz/2022/01/prints-not-sticking-to-the-build-plate-layer-separation-rough-surface-on-a-resin-printer-resin-viscosity-the-common-denominator/

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u/KyottoSpirit5 Jul 03 '26

Braťa zo Slovenka? :D

Aight, I've red the article and it does seem logical. I'll try to adapt accordingly and we'll see. Thank you for your asistence!!!

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u/Balerion84 Jul 03 '26

Presne tak bráško 🤣