Removing Single-Layer Platform Failures from FEP?

[C855B]

Had an interesting failure yesterday with a 12-up print on an original Photon. Half the objects printed fine, the other six printed only the bottom layer of the platform. Appearances are it was a slicer failure, so I changed the object positioning and supports, and re-sliced. No big deal.  :shoulder-shrug:

However, peeling single printed layers off the FEP was a pain. I was able to get five of the six to release, slightly flexing the FEP from underneath with a fingertip to expose enough edge to snag with a fingernail. (Everything thoroughly rinsed first!) One would just not release, so in the effort I ended-up stretching the FEP in that one spot trying to catch the edge. FEP is ruined, of course, so the vat is on the bench to change it out.

Any other experience with this? There has to be a way to coax these micro-thin leftovers off the FEP without destroying it.

One thought I had is to post-cure the vat/FEP to further harden the resin. Maybe that will be enough to help with the flex and peel approach?

[rodsup9000]

I've used a single edge razor a couple of times to get some off. Most times There has been a couple of times that it has happened, and I didn't even drain the vat.

[CNR5529]

Sort of in line with what you were suggesting, in the new firmware update, the Photon S has a built in feature to expose the whole screen with the build platform out of the way. Doing this hardens a full rectangular layer of resin, and traps any stuck on pieces at the same time. Because it has straight edges, it is easier to use the plastic scraper to pick it off the fep without causing damage. I've done it 2-3 times now and it works fairly well.

[Wutter]

I've had this happen to me before, so what I do is empty the resin from the vat and then fill the vat with 91% isopropyl alcohol to soak it and then lightly press around the perimeter of the stuck spot from the bottom of the FEP. After a few repeated swirls it will start to peel up around the edges and you can remove it soon after. Do not try and scrape from the top because it's a super easy way to accidentally poke a hole in the FEP

[John]

I've had this happen to me before, so what I do is empty the resin from the vat and then fill the vat with 91% isopropyl alcohol to soak it and then lightly press around the perimeter of the stuck spot from the bottom of the FEP. After a few repeated swirls it will start to peel up around the edges and you can remove it soon after.

Yes ..

Do not try and scrape from the top because it's a super easy way to accidentally poke a hole in the FEP

I learned this the hard way

[C855B]

Sort of in line with what you were suggesting, in the new firmware update, the Photon S has a built in feature to expose the whole screen with the build platform out of the way. Doing this hardens a full rectangular layer of resin, and traps any stuck on pieces at the same time. Because it has straight edges, it is easier to use the plastic scraper to pick it off the fep without causing damage. I've done it 2-3 times now and it works fairly well.

I was thinking of mentioning this as a solution, that I don't have without the new board, unfortunately. This is also something that might be possible by manipulating slicer settings to move the platform to a higher first exposure position with a no-platform big rectangle, so let me think on this a bit.

Now here's a wacky one for everybody - I was able to save the FEP. It dawned on me from many years of working with various plastics under tension that it might un-deform with application of a little heat. So with nothing to lose I judiciously applied a heat gun... voilà! The moment the hot air was aimed at the film I could hear the "drum" get lower in pitch and then re-tension when heat was removed... with the stretched bubble noticeably smaller. Repeated the process a few times, now the bruise is barely visible and the film fully re-tensioned. After leak testing with alcohol it is now in the machine printing the next batch. Who'd a thunk?

[CNR5529]

That is genius! Will have to remember that one for the inevitable future oopsies.

[AlwaysSolutions]

I bought a package of finger cots so I could "glove up" just a finger and thumb and scrape it off or push it out of the way with my fingernail.  Or combine the plastic scraper with a finger assist.  Big pieces I can take out easily, it's those little ones that I usually can't recover without a full cleaning.  Sometimes if it's just a print setting I got wrong I'll leave it there and print on top of it if it truly is a single layer or two and not an entire print that just stuck (those failures tend to be thicker.)  Use your best judgement with a lot of caution if attempting that method.  For your particular instance I'd do the finger cot to get an edge to lift with the plastic scraper to help load it up and remove it.

Edit to add: also you don't want to be too aggressive as you could deform the FEP and you'll actually see fingernail marks in your prints!