Form1+ laser flare issues illustrated - pics and video

I do also think Formlabs cares. However iN this case I asked Formlabs if I could do similar tests to these since nothing seemed to be working, and they told me no and that it wasn’t the flare. So sometimes the official channels just don’t w9rk.

Video 2: showing the same tall grey part prints from above, also I show the last laser rotation. The same grey parts are running again now, but have a couple of hours to go - so I’ll be posting pics of them tomorrow (nearly midnight here).

They will show very similar flaking, but because I rotated the laser, the flaking and surface corrugation will be on the rear faces of the parts instead of the front.

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Video is set to private.

oops - thanks - should be public now

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Excellent work Kevin. I wish you worked for FormLabs. (That’s nothing against FormLabs)

So having rotated my laser 180deg again as shown in video2 above, so that the brightest part of the flare is now pointing to the rear of the machine - and having run the same tall parts again as shown in my second post above - the flaking and surface corrugation has switched sides to the rear facing sides of the parts.

contrast with the front faces which are now clear

I wont’ bother with another video on this, they take forever to upload and edit on youtube, and I think the case is now clear. I’ll focus on my iris design now - if (that’s a big “if” btw) I have any success I’ll start a new thread on that.

Thanks for all the positive feedback. I’d be lying if I said my motivation for publishing this stuff was purely selfless - it’s also partly to be judged my peers.

Special thanks to @JoshK, @RocusHalbasch, and @Monger_Designs who actually did the hard work first of identifying the issue and all the dialogue with FL support ruling out standard issues like dirty mirrors etc…


Thanks a lot for your hard work.

Its great that can help people to resolve this ( including to formlabs )


Thank you SO MUCH for taking time to documenting your tests and findings. I think we can all agree that it not great to have to go to such lengths to prove that there is a problem. I don’t think that threats about voiding your warranty helps… what else are you supposed to do if they keep denying there’s a problem.

Although I have a lot of experience in FFF, I’m very new to SLA printing and have only had my printer for a couple of months. I’ve been experiencing this problem from day 1. I received my printer back from its second set of “repairs” a couple of days ago and the first thing I did was run the laser test.

It was so disheartening to see almost the exact same laser test pattern. I felt like I was banging my head up against a brick wall. Reading your post and seeing you videos really helped as like you I’ve started to video document my workflow and problems in order to prove that it’s not dirty mirrors, tanks and old resin etc.

Yesterdays laser tests after second FormLabs repair

Previous laser tests.

I printed a test part and had the exact same results on the part surfaces in the exact same places even thought I was using the newer version of PreForm. The print quality seemed to be better on the other surfaces but I expect that was due to me using fresh resin.

Like you, I’m having to strain and waste resin and time for every print in order to remove the build up of jello. But this is a waste of time as even with fresh resin the print comes out with pour surfaces in areas.

The thing is, it’s not just the poor surfaces, it’s my belief that that your resin is degrading with every print, even if you strain the jello out. It’s not the same as fetching out cured plastic from failed prints with a comb etc.

Thanks for sharing your Tall Thin Wall calibration piece. I will print it today and see if I get similar results.



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Hi Steve,

I noticed your previous thread and the excellently defined pictures of your laser spot test. One question - which way is it oriented? By which I mean draw a line between the “rabbit ears” - through the centre and through the opposite “carrot” - how does that line orient with your machine?

That will dictate whether you’ll see flaking on my test parts above - you may need to rotate the parts in Preform to match the flare alignment to see similar results. Note - you can lock the x&y rotation axes in the rotation tab so that you can rotate the parts without losing the supports.


Hi Kevin,

See pic below for the orientation of the laser flares.

@Steve_Johnstone So - to my eyes your flare seems to be very similar to mine, with the “carrot” being the brightest part - it is difficult to be certain of course, the base of the right hand rabbit ear also looks pretty bright - but I would guess that since it is similarly oriented to how mine is currently - you may have similar effects to my last post - ie flaking on the rear faces of the parts.

Depending on how bright that right hand rabbit ear base is - I guess you could also see some flaking on the front faces as well - but I would be very very surprised if you had flaking on the side faces.

Look forward to your results.

I’m getting closer to finishing my sample print, which should not require any orientation to demonstrate the problem, and should represent the severity of the flare in all directions, resulting in something like a flare fingerprint. When I do finish it I’ll post it here.

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I had some spare time this afternoon so photographed the parts I was referring to in my first reply.

All printed in FL Clear v1 resin, 0.1mm layer height.

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@Steve_Johnstone please don’t get me wrong - I can see you’ve had a lot of frustration - but porous parts don’t necessarily indicate laser flare issues to me - since laser flare is an issue with overcuring - rather than missed curing. I’m not saying for sure those issues are not connected to your laser flare.

However - the first thing I noticed was the “river-bed” type separation in your bases - to me this indicates that you may need to lower your build platform.

The Form1+ seems to be particularly susceptible (much more so than the original Form1) to air-bubbles working their way into parts - which I’ve noticed seems to occur a lot more when the bases have “river bed” style separation. Perhaps air bubbles are actually infiltrating the part all the way from the base? it seems unlikely - I never thought to snap all the supports on a bubbled part to check for any hollow ones …

Also when parts have “trapped-air-cells” that occur during the print - (see @RocusHalbasch very good explanation of that here Clustered or bubble of cured resin) - causing an air bubble to burst through the part wall - and infiltrate the part - causing porosity.

Note that porous parts are usually much more porous than they actually appear to be - since liquid resin inside solid looks solid - you have to break the part into pieces to really see how hollow it is … and that will help you track down where the original air bubble found it’s way in…


@KevinHolmes Thanks for commenting on @RocusHalbasch post about the “trapped-air-cells” that problem has been puzzling me for a while. It is good to rule this laser issue as the cause. I have with some effort ruled out air being trapped in the part. For a number of my prints the voids only became apparent after washing in IPA and drying. To me that says pockets of uncured resin and not air.

Hi Kevin,

Thanks for the detailed reply. I hope you don’t mind but I’ve made a video response as its just quicker for me. The links for the files for the original parts are below -

Thanks again,


@EvanFoss what happens is that the air bubble “travels” through the part and can leave liquid resin behind it, hence you can get tunnels filled with liquid resin (that are invisible until you break the part open) - and airbubbles at the end of the tunnels just under the surface of the part. I saw this when I printed some glasses arms - there was a “trapped-air-cell” near the lowest (first printed) point of the part - an air bubble formed, broke the surface of the part, then “tunnelled” it’s way through almost the entire length of the arm - leaving a pit and a bubble under the surface near the end (last printed) of the arm.

I was initially completely baffled as to how it happened - until I broke it apart and saw the liquid resin tunnel reaching all the way back to the “trapped air cell”.


@KevinHolmes Thanks for the explanation. I probably never would have figured that out.

The following is my test. I was not happy with the quality of my photos taken through the printers cover so I took a different method. Our lab used to have a dark room and I saved some of the supplies. I took a sheet of Kodak photograph paper and taped it flat to a sheet of acrylic. I then put that in the printer face down. Yes it is sitting on top of the resin tray fixture and not in it but the point is that it should still be level. If people (in ether the user group or formlabs) want it done better I can find a better scheme to get the paper flat in the printer but for now I think this proves the point.

Never to be accused of a safety violation.

How it was mounted.

How it was setup.

What I saw.

@Steve_Johnstone - as I comment in reply to @EvanFoss - trapped cell bubbles travel - and actually the effects of a trapped air cell are not typically obvious where the bubble enters - but at a completely different location in the part.

To rule out the potential trapped air cell you highlighted, you’ll need to break your part in pieces and wash it in IPA to see if there are any liquid resin filled hollows/tunnels.

As for the lower area pits/porosity - I can only theorise that perhaps you have bubbles travelling up through your base and through your supports - it does sound unlikely I know - but it’s easy to check if you still have the supports and the part - break open all the supports and see if there are any liquid tunnels in them.