"Cracked" during print Form 2

What could cause a crack like this in a part? This is the second time I’ve had this occur in a part during the printing process. I have checked the tank and both times I did not find any cured resin.


Post a screengrab of the model with supports from in PreForm. And a picture of the shard that’s being busted off.

I have just had a similar cracking issue on my Form 2 yesterday. I have attached a couple of pictures. At first I thought that I may have done it myself when I was prying it off the print bed (I use the pry tool they sent with the printer), but now I am starting to wonder. Afterward, it did spend about 4 hours in my UV chamber. I did not notice it until I pulled it out of the UV chamber although I did not take a close look at it before that. To me it’s almost like some internal pressure caused it? Just a guess. But more likely, I got to aggressive with the pry tool. Anybody have any ideas?

Wondering if there if there is post shrinkage with the material or resin batch. No experience with these form2 runs yet but have made many resin models and sometimes material thicknesses can cause stresses when cruring. Plan on using my form2 for casting and pattern making…I am a sculptor with my own foundry and love building stuff wargin.com if your interested . Just received my form2 a few weeks ago and so busy…its still in the box …UGH!

Here’s a clip of the supports for this part. The thing that confused me the most is that shard is no where to be found. I have checked the tank multiple times and there is nothing.

4 hours is probably too long to be curing, too much UV light can cause damage.

No shard in the tank means your problem isn’t breaking. Now you’ve added this additional detail, the problem is print-failure, not breakage. You need to look more carefully, and I bet you’ll find a buildup of cured resin stuck to the bottom of the resin tank in the area where the print was defective.

Here’s what a similar print-failure looked like, from my Form1+.

When I was a mechanical engineer I preformed FEM analysis on all parts to determine stresses that could occur under use conditions. If the VM stress was high I would thicken that part of the component.
Here with FL2 I am building models and counting on Preform to determine stresses when printing.
I don’t know if Preform IS doing any sort of structural analysis when it provides supports.
Certainly it does no stress analysis of the part itself.
A cracked part may indicate an overstress.

A cracked part would have left a corresponding shard floating in the resin tank. No shard reported = this is not a fractured break in the print. The missing area simply didn’t get printed.

Based on nearly 2 years of FormLab printer experience, I would say the only explanation is that this is simply a case of a failure during printing. The cured resin that should be filling the corner that appears to have broken away is probably stuck to the bottom of the resin tank…

So how do I avoid this in the future?

Assuming there’s nothing with your printer, you have to learn how to avoid this by trial and error. There’s no “equation”. The quality of the print depends on the shape/size/orientation of the model and the supports that are present. Your print failed in the orientation you chose. Make sure there’s nothing stuck to the bottom of the resin tank, and that there’s no flotsam of partially cured resin floating around in the tank, and try your print again with a different orientation and maybe more supports…

Try to roll the part a little more so the bottom isn’t so flat to the tank, increase the vertical angle a little more and change location on the build platform.
Hefty part like that has a lot of tear force when peeling.

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