Did a print yesterday which had some parts fail, I removed the build platform, put a lid on the resin tray and left it until today to check the tray for debris & try a reprint. This is what I found.
Needless to say I have a printer with around 150ml of resin inside it, including the mirror. Waiting for support to get back to me regarding cleaning, however, I’ll never leave a tray containing resin in the machine again and will always check it if there are print failures. - Hard lesson…
Just found an old thread about the same issue, wish i’d seen it before.
Could this happen on a FormLabs 2?
How many liters of Resin on that tray?
I suppose it could although I’m not really sure why it would happen.
There were 3 or 4 other cracks round the back edge & the silicon layer had resin under it that had actually cured. There were around 150ml of resin in the tray at the time. Most of it ended up inside the printer
Looking at the cracks, I’d offer the following explanation…
The three cracks at the back edge all propagate from the bottom of the tank. The left two don’t even look like they propagated all the way to the top edge. This suggests to me that there was a large force applied at/near the center of the tank, deforming the bottom of the tank downward, cracking the back edge open from the bottom. The tank is supported by the mounting rails front-to-back, so the only way it could bend is laterally as it appears to have in the pictures you posted.
When your print failed, I bet a “blob” slowly built up on the resin tray bottom and each time the build platform descended for the next layer it pushed on that blob ultimately fracturing the tank. You didn’t notice when you removed the failed print but I bet is was already broken then.
Yikes. There are a few things that can cause the tank to weaken including solvents like IPA on the acrylic. We haven’t seen much tank cracking from normal stresses during printing but here’s to hoping our support team is able to help find the root cause and get you up and running again quickly.
That Was my thread. Don’t leave trays in the printer.
Thanks @Frew, I’ve never used IPA on my tanks, if I clean the bottoms it’s always with Novus, however, I’m really careful about getting fingerprints etc on them so hardly ever need to clean them.
Support have been in touch with instructions on partially stripping down the machine for cleaning & have offered a replacement tank. I have no idea why it cracked but I think that @Randy_Cohen may be right, there was a ‘blob’, remnants of a failed part, on the build platform, so his explanation could be what happened although the blob was closer to the back of the tank than the centre.
I think it would be a good idea for FL to tell customers to check tanks regularly for signs of cracking and particularly after failed prints. Because the base is swimming with resin I’ll have to go further than the partial strip down instructions & remove the whole main frame including the larger PCB, I only hope it works after reassembly, if it doesn’t at least I’ll be able to ship it for repair which is out of the question with the resin in the base.
Cheers 
Thanks @Randy_Cohen I think your probably right.
@rclaborne As I said I wish I’d seen it earlier and I will be taking your advice and will never leave a tank in the machine again.
Just for info, i finally put the machine back together last week and it’s printing perfectly. I had to strip it down much further than the FL instructions. The resin had spilled into the base and was under the main frame of the machine as well as the the main PCB so they had to come out as well so in the end I had all the covers off & the main PCB out.
The resin had also spilled between the two layers of the tray carrier, that was the hardest place to remove it from, also the heat sink glue on the laser PCB soaks up resin like a sponge, i was wiping that away for a couple of days.
After reassembly I did a print that took 24 minutes then went straight on to a full build platform. No defects. Huge sigh of relief.
I also have my replacement tank from FL, which, and I don’t want to stoke the FL 1+ debate here, but it was out of stock in the EU(UK) when support placed the order…
Happy printing folks
Yes, hopefully you noticed that one screw on the bottom/rear that is shorter than the others. Otherwise, yikes.
Yes, actually both were shorter, support did point that out though in their instructions
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