I am not sure if this has been mentioned yet, or if it is even possible, it might be nice if the resins started out clear then changed to their final opaque color after the resin has been cured with the laser. That way we could see if any cured bits remained in the tank after each print. This would make it much easier to keep the tanks clean.
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It’s completely possible and there are resins like this. The DWS resin I tested a while ago is a clear resin with a very light blue tint to it, and when it cures it turns milky white. Unfortunately that resin did not work very well with the form1.
Monger - thank you for your reply. It’s nice to know that the possibility exists.
For me, keeping the resin tray debris free is the biggest struggle I have with the Form1. I have been emptying the tray after every few prints. I strain the resin and check the bottom for anything sticking to it. I tried the comb method, but have been burnt a couple of times having missed some pieces. What method do you use to check the tray for debris?
I think the purpose for the color (pigment) is that it is a blocker so the laser light doesn’t refract all over and create blobs. Why Black shows the crispest edges and clear is the smoothest (clear does have a blocker in it).
I think if the color changed as it was being exposed it might cause problems as a model is being printed.
Almost, but not quite.
Pigments absorb the light (so yes, they block the laser), but the only thing that affects is cure depth. Not laser reflecting or refracting in unwanted directions, but laser curing too deep (i.e. too high up).
You know those rough surfaces you get on the bottom of your prints? Not the ones from supports? That’s exactly it. The more absorbing the pigment in the resin, the less overshoot you’ll get and the better defined the surfaces will be.
A resin that starts transparent and changes to opaque during curing would be no worse, as far as print quality is concerned, than a resin that’s transparent and stays that way.
@BenAlbers What I do is let the tank sit for a few hours, or a day. Then I tilt it slowly and pour out the resin into a plastic container through a metal strainer. Most of the large chunks (if any) will be on the bottom of the tank. You can then gently scrape off the remaining few drops of resin and the chunks out of of the tank. After the tank is clear of debris, pour the resin back and add some fresh resin. Mix well with the scraper and it’s ready to go.
I’ve noticed that more chunks can occur from badly supported parts than failures. Usually with failures it’s just a chunk of cured resin that you can gently lift off the bottom, but with badly supported overhangs, you can get lots of tiny chunks inside the resin.
Therefore, I meticulously make sure that all overhangs are supported on the model, even if it’s part of some detail. There are usually always some unsupported areas. Use the layer stepper to look through and make sure you never get any detail that is hanging in mid air with no supports, no matter how small it is.
Sorry for the tangent here, but…
You know what i keep finding weird?
How often people need to fish stuff out of their Form1 tanks here.
I’ve been messing with a DIY laser-based SLA printer for a year now and the ONLY times i’ve had to clear the tank of debris was when i really messed up badly setting the print up, or there was a hardware failure during a print (stepper drivers overheating, wire got loose in the middle of a print etc.).
Stuff always sticks so well to the build platform (i’m using a perforated steel plate) it’s a problem to get it OFF the platform - there’s no way in hell it could ever stick to the PDMS better than to the platform.
I wonder if it’s due to PreForm’s supports (and bed-of-nails) implementation, or if it doesn’t cure the first layers REALLY hard on purpose, to make it easier to remove from the platform.
Note that i’m still waiting for my Form1+, so this is just based on my observations here on the forum.
Monger - thank you for taking time to reply. Your process is almost identical to what I do to keep my tanks clean.
The debris issue is less of an issue now that Preform has been updated several times. When I first received my Form1 it was an issue after every print and if I didn’t take the time to properly clean the tank the next print was almost always a total failure. I had a couple of failures that ruined two of my tanks. So not only was it a mess to clean up, it was expensive.
I think that there is some room for improvement in making the tanks easier to keep clean. Having a clear liquid resin that turned opaque when cured could help.
What other things could be added to the Form1 to make it easier to maintain?
Here’s a really daft “mechanical” idea…
Add a strainer to the tank that’s vertical and slides back and forth over the width or length of the tank.
Before each print, you’d first scrape (massage) the tank with the spatula to dislodge the cured resin from the PDMS, then “ride” the strainer from one end of the tank to the other, straining the resin and shoving all the debris to one edge where it can easily be removed.
@Ante_Vukorepa to set your mind at ease I’ve been using Form1 machines since the Kickstarter program, and the only time I have had to fish anything out of a tank is when hardware was failing or I made a mistake like printing something with an unsupported area. The reason you see it on the forums so much I think is largely due to the fact this is where people come when things go wrong, so usually in one of those two circumstances.
I do occasionally rake my tank just in case but I have yet to find anything outside of the previously mentioned circumstances.
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Thanks, i needed that.
I know judging a product by forums and support requests is very very misleading (because of the negative bias), but it still gets to me sometimes (usually the closer to ship date i get).
Ante - The Form1 is an amazing machine. I have no doubt you will be very happy with your purchase. It is also comforting to know that if you do run into any issues, Formlabs does a great job supporting the printer.
My woes about debris issues are nitpicking a great printer. I feel very fortunate to own a Form1. I can’t think of another printer currently on the market that I would rather have.
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Hey Monger, you do a lot of experimenting with resins, how about a Form1+ laser exposure table? 
I found it works awesome for mixing FormLabs colors or using up old B9 resin. Enjoy.
While all the FormLabs combos I tried printed well, just White into Black had reduced shelf life.
PS - The accuracy of this data is insane.
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Ooooh! That’s a great idea. And I can print one in ABS with my Replicator. A comb that’s as “deep” as the tank is, that has “ears” that hang over the outside sides of the tank. Drop comb in to the tank at one side and drag across to the other. There’s clearance enough between the sides of the tank and the built platform that the comb could just stay there, holding any debris in check, for removal at some later convenient time! As I’m on vacation this week, I think I’ll take a whack at a design, something like this…
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Randy, You might want a clip on that to keep it from working it’s way back. If that got snagged under the build platform during a peel that wouldn’t be good.
I had thought the same thing, Josh. But I need to pull a Resin tank out and measure before I figured it made sense to invest in adding that detail. But yeah, I was thinking that the “ears” could have a feature that wrapped around the outside corner of the tank, so it “snapped” up against the side and was held secure. That’s why I added the little “feet” at the bottom of the comb, as stand-offs to make room for any debris scavenged by the comb.
Something like this is probably more like what you’re thinking…
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Yea that looks safer. When you get it done a picture would be cool 
Yup, awesome work, that’s almost exactly what i had in mind!
Well then, I’ll design one to actual dimensions (vs. my freehand, here) and print it up. Looks like it works, I’ll post a STL for anyone else to print (or have printed) too!
Did this ever work? ehhe