Moai Laser Safety - running the printer makes my eyes hurt!


I have a Formlabs Form 2 which I’ve run for years. Never had any eye discomfort while operating it or staring for a long time at prints in progress.

The Moai makes my eyes hurt when printing. I have followed the assembly instructions to the letter and it appears to be light tight. I have taken to covering the top of the machine with a dark cotton pillow case while printing. When I do that, my eyes don’t hurt during printing. But then I can’t see what’s going on in there.

Anyone else have this problem? Is the front door acrylic of the machine laser safe? How could I verify this? Is there a material or device that could reveal the presence of stray laser light emanating from the machine? Should there be a felt strip around the edges of the door as on the Form 2, to ensure a light tight seal?

Thanks in advance.



To be completely honest i have no idea how that is possible…

The gap between the vat and the vat platform is MINIMAL so its really hard to see the laser working and with the door closed how could the laser hurt your eyes??

Are you using clear resin? And looking at it while printing with the door open?

The only thing i can remember is maybe the “fumes” from the resin you are using are irritating your eyes. I highly doubt its the laser to be honest.



I don’t have any problems with mine. Even when I open the door during a print in order to check it out - still no problem. I’ve come to think the included safety glasses were a bit superfluous. I guess they were useful when I first built the printer and needed to run it with the side off for leveling.

I have used peopoly blue, peopoly uv green and peopoly clear tough resins. None had any discernible affect on my eyes while printing.

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Thanks for the replies. I am running with the exact same resins and post-processing equipment and process that I use on the Form 2. These are grey and black ApplyLabWork resins, no clear or transparent resin. I print with the Moai door closed and locked, never opening until after the print is finished. I can not see the laser spot moving in the vat with the resins I use.

I will try to locate some sort of indicator to detect stray UV light.



There are a few on that will detect the 405nm (upper uva) that is output by the moai. I couldn’t find anything on amazon. Unfortunately the little project detectors such as the adafruit uv detector only go up to 390nm.

The ones on aliexpress such as this one are pretty expensive at $150usd. If you’re handy with electronics, you could probably get the parts from mouser and build one yourself.

I wonder if you’re not having a reaction to the scent that is being emitted when the resin is cooked. Allergies to the resin are supposed to be somewhat common.

You can read a little about UV light here:

Fortunately, 405nm used in MOAI being at the top end of the UV spectrum and almost visible is the least dangerous UV light.



its most likely the fumes from the resin if you are heating it up, happens to me from time to time.



Thanks for the info on UV detectors. I see that some folks are using glow-in-the-dark sheets with UV lasers to create glowing artwork. I wonder if some glow-in-the-dark stickers or plastic sheets might make for a cheap detector?

As to the resin fumes being the cause, I’m open to this hypothesis but we’d first have to account for why the exact same resin, in the Form 2, being heated to the same temperature as in the Moai, does not cause this issue. The two printers sit next to each other, literally 30mm apart. Same environmental conditions. The eye discomfort issue also presents itself when the Moai heater is not used. Resin at room temp.



Well the sheets are cheap. It seems hard to believe that enough UV light would escape to show up on something like that but I guess you never know. It’s only 150mw.



same exact resins used for each?



“same exact resins used for each?”

Not only the same exact resins, but from the same (well shaken) bottles.



peoply resins dont bother me at all. when i started using Siraya resin the fumes made my eyes hurt, i started using goggles when i work with siraya resin, doesnt happen with peopoly resins.



If thats the case then im almost sure its the “fumes” and not the laser. Keep us posted



it would be very hard to get leaked laser because not only the panel blocks out more uv light than form2’s orange cover. you actually have to be in the focal distance to get damaged by this uv led. this means you have to be around 320mm distance at the focal point, that invovles you sticking your head in to an open door, without a resin tank and look down.

A much more likely source of problem is that your curing equipment is leaking UV light. Those lights can sour your eye much easier because they just blanket the area instead of pinpointing like a laser



OK I think I have solved it. To recap:

It’s not the fumes - because I use the same materials in the Form 2 and no problem, and there’s no problem if I cover the MOAI with a pillow case and never view the print in progress.

It’s not anything else in the process, washing curing, etc, because these are the same equipment and process used when I print via Form 2. (I use a Form Cure and it has no UV leakage).

The issue is HOW I view the print in progress. With the Form 2, I just look through the orange cover and see. With the MOAI, I can’t do that because as the previous poster confirmed, and we all know from experience, the MOAI acrylic is darker. Too dark for ambient light to reveal the interior.

So what do I do? I shine a very bright 5.11 ATAC L2 (222 lumens) LED flashlight through the closed and locked front door, and as I realize now often times (far too often) as I manuever the light beam to strike my print in progress, the very bright LED light reflects off the front surface back into my eye. I believe now that this is causing the eye pain.

I will rig up an internal light on a momentary switch to see if this fixes the problem.



Interior lights are on my to-do list for moai mods. I was going to simply use some cheap LED strip lights. You can get them at walmart for like $5 with power supply, remote control and all. I was also thinking of replacing the moai door with a piece of clear acrylic.

Those are going to have to wait, as I’ve started working on building a project tripod and I don’t want to add anything that may get in the way of the new rail system.



Ditched the pillow case, stopped using the tactical flashlight. No more eye pain. Case closed.