Need help - cleaning the first-surface mirrors in the Form1

I got my Form1 today! I’ve done a cursory inspection and it seems to be free of any damage. The machine also seem to be of nice quality.

However, it’s a little dusty. I know enough to recognize a first-surface mirror when I see one, but I don’t really know enough about them to clean one properly. Does anyone here have any tips - specifically tips for cleaning the mirrors inside this machine. I’ve seen some people recommend cleaning this type of mirror underwater; I suspect that isn’t an option here. I saw a recommendation to use pure acetone and I also saw a recommendation to use alcohol. I’m sure if I search “Google” enough I will find a consensus, but an official word from Formlabs would be preferable. I think I’ll start with a light dusting with a lens brush in the meantime.

People say there are “galvos” inside the machine. Now, before I bought this thing I hadn’t even heard of a galvo. Has anyone cleaned the mirrors attached to the galvos yet? The one I can see (which I’ve been lead to believe is the second mirror the laser hits*) looks like it might be a little dusty. With the recent _painstaking calibration _post on Kickstarter fresh in my memory I am hesitant to touch them. I’m also inclined to believe that it would be better if these mirrors were as close to perfectly clean as possible.

*correction: it’s actually a stationary mirror and it’s the third mirror in the laser’s path

If I promise to be extra gentle would it be OK to clean these mirrors?

Is there a recommended product to use? A recommended procedure?

Is there a way to access the galvos? Perhaps by removing the back cover or something.

Sweet, I love a forum that actually allows high-resolution photos. :slight_smile:

… reducing the size of the in-post photo to a thumbnail would be nice though.

I would like to know how this passed the final test and calibration.  Maybe Formlabs has a dust problem, not a quality problem.  Unless this is box dust.  How many other printers that are acting funny have mirrors that are covered in dust.

I wonder how a print would come out with all the dust.

Ah cool, you got yours! :smiley:

Mine came with dusty mirrors, too. I gave them a light dusting before I started printing, using one of these:

From an email I received from Jory at Formlabs:

“You can polish the mirror with a microfiber cloth of lens brush, although light dust will not effect the quality of your prints.”

The mirror is glass, so it shouldn’t scratch the way the acrylic parts can. After the inital dusting, I used a very-slightly-moistened microfiber cloth to give it a light  polish. If I recall correctly, I also used the duster on the galvo mirrors, though it was a very light dusting.

Oh whoops: correction. I didn’t dust the galvos, I dusted the mirror below it (if I’m seeing it right).

Congrats on getting your printer! I cleaned my main mirror with a quick burst of compressed air (the safe for electronics kind, not that I’ve seen NOT safe for electronics ones these days). I didn’t touch the galvos cause I definitely didn’t want to mess anything up. It seems to have stayed clean since the spray, so I’m guessing the dust comes from them sitting in a production line, waiting for their orange covers.

You can read Bunnie’s blog to see how to get to the galvos by completely taking apart the machine :slight_smile:


Hirudin, whatever you do do not be tempted to use Acetone while the mirror is inside the unit.  There will be many plastic parts in there and the Acetone will just eat them up if you spill, far safer with the alcohol.  The IPA you will be using for your rinsing bath regularly gets used in industrial environments on PCB circuits. so with care you can use that I am sure.

I would only use it for grease marks and finger prints.  Dust removal tips are already covered by the previous posts :slight_smile:


Thanks guys!

Yeah, it’s dustier than I would have expected. It’s entirely possible it was from the box, the shipping, or from the assembly.


Yea-yer! It’s here!
I’ll look into those Swiffer dusters. You’re right, that mirror I was guessing was a galvo mirror is actually the one below it (mirror #3 in the laser’s path).

A quick note: I don’t think the mirrors are glass… or I should say: although the main component of these mirrors is glass the reflective coating is actually exposed. On these “first surface” (or “front surface”) mirrors the part that you would clean is actually aluminum or some other metal. In my quick research I’ve learned that the metal might have a thin coating on top. They use these kinds of mirrors because normal mirrors have internal reflections which would turn the single laser line into many laser lines. Or… that’s my understanding anyway - entirely possible I’m wrong.
Here’s a website with an image that explains it pretty well…



Thanks for the link to the teardown! I’d seen it before but forgot about it.


I will probably heed your warning about acetone. A similar warning was posted in the same place that I saw acetone suggested, but this one warned that it’s essentially paint stripper so has the potential of ruining painted parts. The thinned paint also has potential to get on and stick to the mirror as well. If I do use acetone (unlikely) I’ll be sure to be really careful.

An interesting thing mentioned on that page I linked: mirrors are only roughly 90% efficient. That means by the time the laser light hits the bottom of the resin reservoir after bouncing off four mirrors it only has ~65% of its energy left. It probably loses about… 3 - 5% more going through the acrylic and who knows how much going through the silicone.

I think you just crank up the power to compensate for the losses so I don’t think it’s a problem or anything, it’s just interesting.

Oops… I guess I deleted the “x” off the end of this link…

(if this link doesn’t have an “x” at the end - manually add it)

I’d be tempted not to use any solvents at all just enter ‘Lens Cleaning’ into Amazon for camera optics solutions and always try a non contact blower bulb first.

Alrighty, a little update…

I decided that I didn’t want to continue until I had the mirrors cleaned. To that end I started taking the printer apart. I now know that the mirrors in the back can be reached by removing four screws holding on the back panel (see picture - the two marked screws and the opposite two on the other side).

In the course of cleaning the small stationary mirror (#3) with a Q-tip I ended up moving one of the galvo mirrors. :frowning: Although it would be possible to clean mirror #3 from the rear without hitting the galvo mirror, it wouldn’t be terribly easy. Since I had already hit the galvo I decided to try cleaning them too. Basically, I’m hoping it won’t be a problem. We’ll see I guess.

I ended up using some Rexton brand “Lens & Optical Surface Cleaner” that I believe I got from Surplus Shed a long time ago, some canned air, a few Q-tips, and a microfiber cloth to clean the mirrors. I’m not sure if using Q-tips was a wise choice but it’s what I had on hand.

The dust was more stubborn than I had anticipated and actually required multiple passes.

So, I’m about to start my first print. I’ll set up a camera and record it for a while. I’ll post the video on YouTube.

Here’s the video. It’s… um… pretty boring. :slight_smile:

So Hirudin, how did the first print go.   Please tell me you got time lapse worked out LOL.


It actually didn’t come out too well unfortunately. :frowning: I was printing a set of Settlers of Catan pieces and a bunch of them got stuck together.

By being a little careless I ended up getting a some microfiber cloth lint on the silicone layer in my resin tray. I cleaned it off with an alcohol-dampened Q-tip. The lint came up and I figured the alcohol was gone by the time I added the resin, but there must have been some left over. One way or another hardened resin attached to the two linty spots. Of course, everything around those spots did not print properly. Attached is a photo that shows the spots I’m talking about.

Oh darn… live and learn.

Oh dear.  Well I have seen others getting poor results so I suspect we all need to have some time to become familiar with the machines.

I am sure when you have cleaned everything up it will be much better next time.


I think so too!

Actually, sitting in the alcohol bath they look better. I’ll have a pic of the final parts in a few minutes…

Even though this is a pretty inefficient job for a 3D printer (being that the pieces are simple and mostly square) I think I’ll try it again.

Oops… this is getting off topic quite a bit.

Not the best photo in the world, but here’s the pieces that came off the print base. I put the best example of each piece in the foreground. The red pieces in the background are the originals from the board game.

I created the original models in SolidWorks. I then opened the SolidWorks assembly in Rhino (v4) and exported it as an STL using the settings third image.

I’m curious about the thing about the alcohol on the silicone layer. I was wondering how one would clean the tank if another resin were to go into it, and Formlabs’ help documentation doesn’t actually give a method for cleaning the silicone layer. I assume they may have not found a good way to do it (yet?), or perhaps it’s just not something that can be cleaned without contamination? They only say to scrape off the resin and that that method should be able to get nearly all the resin off the tank. Since I’m experimenting with color and different resins, cleaning the tank between resin changes is something I’d like to do.

Seems like the pieces that did come out came out rather nice. :slight_smile: How do they compare to the originals in terms of size and such?

Oh- one note about the mirror that I encountered last week: small specks of dust won’t really do much to harm your prints, but some of my prints ended up with small holes that ran through the print. The holes were caused by larger dust particles that somehow got into the printer and onto the main mirror. It’s probably good practice to check the mirror between prints as a routine, just in case. ^_^)

I was wondering about cleaning too. I recently tried to scrape out all the resin in my tank. Although the majority of it did come out I wished there was some kind of solvent I could have used to get it all out. In the future I wouldn’t want to switch from, say, black resin to clear without being able to clean the tank. Hopefully the tanks will be reasonably priced and we can just have one tank for each type of resin.

Some of the parts did come out OK, but some of the items were much less dimensionally accurate than I had hoped. The “settlements” (the house-shaped objects) were slightly wedge shaped along the ridge-line of the roof. Also most of the “knights” (horse and rider pieces) didn’t come out very good. Their muzzles and forearms sorta merged together.

The orientation I used seems to have played a large part in these inaccuracies though. I didn’t angle the parts as Formlabs suggests but instead laid them down flat.

I’ve since printed several iterations of the knight piece with its bottom placed flat against the build platform and they’ve come out much better. It’s strange to think that perfectly vertical flats are the least likely kind of geometry to come out correctly, but that has been my experience so far.