The Attack of the Giant Flake

Okay, so… i’ve been trying to print something i’ve already printed fine once (at 0.2mm layer height the first time, at 0.1mm during the latest attempts) in Clear and keep hitting the same wall over and over again.

The part keeps accumulating these large flaps of semi-cured resin on one side. I can’t even call them “flakes” as they’re huge. Eventually, they end up stuck on the bottom of the tank and the print fails, usually near the very end. Now, the fun part is - the flaps are not delaminated parts of the print itself. And they’re way bigger than the usual flakes due to flare.

I’ve recorded a vid to illustrate the consistency of the flaps:

If it weren’t for the damage to surface quality caused by the flaps and removal of flaps, and if they didn’t eventually fail due to accumulation of same flap material on the bottom of the tank, the prints would be fairly successful.

Interesting factoid - the flakes don’t merely accumulate as the print progresses - they start all the way down, near the base. Changing the orientation changes the side most affected - the greatest accumulation is always on the hinge side, from what i can see. I’ve checked the mirror and it’s clean. I blew off, then wiped the dust with a pec-pad just to be on the safe side (even though no amount of dust could cause even curing of flap-like blobs like that).

After the latest failure, i’ve checked the rear mirror (more thoroughly for the first time) and noticed it seems pretty speckly. It also appears to show reddish-hued shifts in surface quality at the very bottom (looks like some kind of an artifact in the silvering) and two very fine, thin “scratches” that aren’t truly scratches, but again, look like a slight defect in the silvering (they’re red and don’t look like they’re on the surface). Both artifacts are at the very bottom, where they couldn’t affect the beam, from what i can tell. Besides, considering i’ve never touched the small mirror, i’m pretty sure those were there from the beginning.

While debugging, i took a look at the laser spot without the cover on (for the first time) and noticed there’s quite a huge halo around it (that’s not normally visible through the cover). How usual an occurrence is this for Form1+? The halo is composed of tiny dots, which to me indicates it’s an artifact of diffraction and probably caused by something very near the laser optics.

I’ve also noticed the laser pattern has a tiny, sharp (higher intensity) line jutting out to the left side (towards the hinge). I’m not sure i’ve noticed that the first time around. I did post some spot photos here on the forum, but can’t seem to find them at the moment.

I’m printing @KevinHolmes’ tall cross test now, wonder if the result will be the same.
If they print fine / without flakes/flaps, then i’ve got no clue what’s going on here.

Well that did not end well, lol.

The hinge side is a mess:

I stopped the print, cause that side was a total writeoff even this early in the print.
The peel side was printing fine, though, although with some minor flaking:

Some bizarre things i’ve noticed…

The hinge side now has a nice cross-shaped ghost image on the PDMS. Incredibly, but even these 100 layers or so managed to produce VERY noticeable ghosting (and no, it does not rub off). Also, the prints were warm to the touch a minute or two after i’ve cancelled the print. I don’t think i’ve ever noticed that before, at least not to that degree. Too bad the resin is clear - i had no way of measuring the temperature, only had an IR thermometer nearby.

Made another attempt at printing the tall crosses.
Same deal.

I’ve got no idea what’s going on and what’s wrong all of a sudden.
There were more flakes this time around than on the previous attempts and there was no side preference - just flakes and flaps of resin all over the place, and a cured blob on the PDMS under the hinge side cross.

Since it’s past 4am here already, think i’m gonna sleep this one over and see if i figure anything out tomorrow.

Side-question: is this the expected amount of bubbling you should be getting from shaking a bottle of Clear resin well?

Yes clear bubbles that bad when I shake it up and if I don’t let it clear up the bubbles are in my print.
Wish I could help with the rest, it looks bad, really bad!

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@Ante_Vukorepa that’s bad news - commiserations.

I also looked for your previous spot photo’s and couldn’t find them. I was looking from your profile page listing all your posts, but then you have been quite prolific :slight_smile: so perhaps they’re still there somewhere…

As for what’s wrong, I’m hesitant to blame the spot halo, it could be normal. It’s very hard to say though because peoples pictures vary so much.

You say you’ve printed fine at 0.2mm in clear and are now seeing issues in 0.1 - but then your min-feature test prints at 0.05mm in black did better than the cross piece tests from your latest print. Although one question there is if you’ve ever printed close to the hinge side previously?

Do you think something has changed - perhaps try those same pieces in black again, or some other parts that have worked fine previously - from a saved form file ? (preserving orientation and platform location).

I’ve previously printed that particular print at 0.2 (the one from the first post, not the crosses). But I’ve printed other stuff fine in Clear at 0.2, 0.1 and 0.05. And i’ve printed near the hinge most of the time.

Never had any gross flaking (tiny blobs of jello here and there sure, anything like the flakes in this thread - nope) nor outright failures until now.

I haven’t changed a thing. In fact, i printed in clear, at a similar position and orientation (different print, though) a day before this happened.

I’ll try printing the butterfly clip (and, if that works, the butterfly logo plate) later today. Then try with the black again to exclude the Clear resin.

@Ante_Vukorepa [quote=“Ante_Vukorepa, post:7, topic:4016”]
I haven’t changed a thing

What I meant was; has your printer behaviour changed - or was it always that way? - and to re-run some earlier successful prints under exact same conditions to check …

It (al)most definitely wasn’t that way until yesterday.
Granted, i never printed the tall cross test, but like i’ve said, i’ve printed the first object just fine (albeit at 0.2mm) and i’ve printed similar shapes in similar positions at a variety of layer heights (0.2, 0.1, 0.05, never tried 0.025) without anything even closely resembling yesterday’s results.

So yes, the printer behaviour seems to have changed.
But i won’t be able to claim that with 100% certainty until i print exactly the same files i’ve printed before, of course.

That said, i can’t see anything specific or wildly different about the recent prints. In fact, i’ve printed a ring (not disc) shape of the same size, position and orientation immediately before the object in the first photo. And there’s nothing about your tall cross-shapes that would cause a total failure. Flaking - sure, but outright failure that early in the print - nope, right?

Agreed - it certainly looks like something broke - hence my earlier commiserations.

But - assuming you wanted to work here in parallel with an FL ticket - and taking as read all the normal questions (which you won’t be able to avoid from FL support…) the first question I have is to absolutely confirm it’s new behaviour.

Next is your super fast PDMS clouding - that sounds really off. No idea if the parts being warm is significant or not - but clouding after 100 layers is very wrong. Could you confirm that with a fresh tank and fresh resin? or a resurfaced tank?

After that I guess comes your observations on the small mirror - I doubt it’ll make a difference but it’s probably worth cleaning it. Not sure what the official FL procedure is, but I clean mine fairly regularly by taking the back off and very lightly (lke micronewtons of pressure) sweeping the dust off with a dry cotton-bud (cue-tip for USA types) - while checking with a very bright torch for remaining dust specks.

At the same time while you have the back off you could check the galvo mirrors (using said bright torch), I really don’t see how they could have picked anything up, but FL support will doubtless ask you to check them at some point anyway …

Haven’t contacted support yet, as it started on saturday (they don’t work weekends anyway). Already have a ticket open re: oddities with black resin, so going to update there and see if they want me to open a new ticket or not.

In the meantime… Got home and replaced the tank with the one i keep the black in.
Going to do some prints to see if they’re any better, on the off chance it was something to do with the resin and/or the tank. If black gives me same results, i’ll then know for sure it’s something with the printer, as i’ve mostly been printing in black for the past few weeks and had no (related) issues.

Re: small mirror - i have some sensor swabs that happen to be just the right size (they’re pec-pads wrapped on a stick, basically, meant for cleaning DSLR sensors).

Re: ghosting - here’s a photo:

And a video:

I killed the print sometime before layer 200 (not 100 as i’ve previously reported). Still, how does 200 layers produce this amount of ghosting? Also, note it’s not a complete cross - it’s the hinge and back side of it only. Very very weird. (BTW, the blob-like shape to the right of the cross in the photo is a reflection.)

Well that was interesting…

Looks much better than Clear and the other tank, but still…
The peel side failed near the end and there’s quite a lot of flaking.

So now i know nothing yet again.
I guess trying to print some “known quantities” (i.e. the butterflies or something similar) is next.

@Ante_Vukorepa, really sorry to see this as your printer seemed to be doing so well. As already mentioned clean all your mirrors, including the galvos, as that’s the first thing they will ask you to do.

Continue on the existing support ticket as that’s what Formlabs prefers and if you don’t hear back after a couple of days just mention it here and I’m sure @Michael_Curry will chase it up. He’s been great with chasing up things with my printer.

I experienced ghosting on my clear cross test. Its really not a very kind test from your PDMS point of view, but seeing your black resin cross test makes me think its a laser problem.

This issue you’re having looks very familiar, unfortunately… I think @Steve_Johnstone might be right and you are having similar problems to what we are/were having before we sent our printers to the Formlabs engineering team…

Here are some pictures for comparison which both Steve and I blame as being a faulty laser:

If any of this seems familiar… I’m afraid you might be having the same problem as we are having… What’s most unusual is that it happened “overnight”. That sort of was the case for me as well… But it doesn’t make sense when appointing it as a laser issue… Anybody have any thoughts on how this issue can occur overnight?

By the way; even with these problems my butterfly print came out just fine… So it doesn’t really seem like a very good benchmark to test if the printer is working properly.

Honestly, I hope that you’ll be able to fix this issue by just cleaning all the mirrors… Though I have the feeling you might have to send in the printer for repair/replacement.

I had a very similar issue with my printer about six months ago. There were huge flakes, ghosting, explosions from time to time. It didn’t matter which resin color I was using, I had basically the same issue. Changing tanks would help a bit, but only for one or two prints, and even those weren’t perfect.

I cleaned my large mirror and my small mirror. The issue persisted. I cleaned my galvo mirrors (very carefully, following the Formlabs doc). The issue persisted. So I asked Adam (the person who wrote the formlabs mirror cleaning doc) to take a look at my printer. We took out the galvo block and he shined a light at the galvo mirrors. He said they were very dirty. Even though I had done the same thing and didn’t see smudges, he was better able to position the light.

So I’d definitely suggest taking a careful look at those galvo mirrors to see if you can detect issues from as many angles as possible. As the instructions say, you can remove the galvo block from the printer, but removing the galvos from the block will kill your calibration.

I can’t say for certain that this is the issue you’re having with your printer, but the images you post are quite similar to what I was dealing with at the time.

@CraigBroady you mentioned your issue with a dirty galvo mirror(s) before (when we were discussing laser flare) - the thing I never understood was - how on earth do you get a dirty galvo mirror???

Seriously - how does it happen? and what kind of dirt?
Those things are “vibrating” at god knows what kind of frequency, so settled dust seems extremely unlikely to me. On top of that they’re pretty much covered from all angles.

So I just don’t see how the galvo mirrors can become dirty after assembly - out of the box sure - but during use??

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I wouldn’t rule out the galvos. I’ve seen multiple cases on the forums that looked a lot like this that where just dirty galvos. Also looking at your halo, I really really doubt that is the culprit. While I disagree with Formlabs that only the center of the laser cures resin I do agree with them partially, I do believe that only very high intensity light cures the resin noticeably and your halo looks like it’s not very high intensity. I had a similar halo however it did not seem to cause giant flakes. As for your little extra line in the spot I’d be interested to know how just how bright it is but still doubt it’s a major component of your problem. The last thing that makes me vaguely inclined to guess the galvo is it happened all of a sudden as opposed to being that way from the beginning, which was common among the posts I’ve seen where it was the galvos.


very carefully, following the Formlabs doc

Where is this magical doc because i am having the same issues.

@RocusHalbasch I wouldn’t rule out a dirty galvo either, and as I said earlier and as @CraigBroady also mentions you need a very bright light (I use a dive torch) shone from side on to really see a mirror surface clearly.

However - I am very curious to hear how the galvo mirrors can get dirty post assembly - and what kind of dirt it was in @CraigBroady’s case.

For my printer it was tricky to say. At the time I was doing quite a bit of testing so components were getting swapped in and out regularly and the back panel was often removed. It’s possible that dust accumulated or that the mirrors got smudged while parts were being removed. While this is not the case with Ante’s printer, the symptoms looks similar.

@Renwick Large mirror cleaning instructions here: Reach out to customer support for a document describing how to clean the other mirrors.