While the parasitic residual resin curing theory is worth serious consideration, I don’t think that is what is happening with the models I’m printing. Here’s why:
We don’t experience that defect with any of the five Form 2 printers we’ve had (we presently have 2 on hand which operate nearly 24/7). We have experienced circular opening distortion only with both of the Form 3 printers we’ve had. This tends to indicate that the issue is Form 3-specific.
That defect is not occurring anywhere else on the model one would expect to see parasitic resin pool. The defect only occurs in circular openings. This tends to indicate that the issue is specific to certain geometries.
The room in which we operate our printers is windowless. The artificial lighting we use in that room does not emit UV light. This tends to indicate that environmental UV light is not affecting the models.
Based on these factors, it is my opinion that parasitic curing of residual resin is not the cause. IMHO, the cause of the misshapen openings is specifically related to some characteristic of the Form 3 and only the Form 3 (or Form 3 firmware) in its present state of development.
If I am wrong and parasitic curing of residual resin is the cause of the misshapen circular openings, it does not explain the other serious defects we see on our Form 3-printed models such as layer shifting, mushy detailing and surface bulging. FL techs suggested two possible causes and recommended solutions:
the models require more support to prevent those defects from occurring. This suggestion is a bit perplexing since, 1) the models print perfectly on our Form 2 with fewer supports, and 2) the Form 3 is explicitly advertised as needing fewer supports and smaller contact points than required by the Form 2 due to the Form 3 placing lower peel stresses on models. When more supports were added, we continued to experience the same defects.
we should only print at 100 microns, not 50 or 25. But test prints at 100 microns exhibited the same defects we experienced at 50 microns. Additionally, the characteristic “Aztec stair-stepping” visible in inclined and curved surfaces printed at 100 microns spoils the surfaces of the models making them unsellable.
So far, the two Form 3 printers we’ve had have not produced a single model our customers would accept. I look forward to running some print tests on our Form 3 with the updated firmware this weekend (the gray resin for the test has shipped, but not yet arrived). The test will include the battleship superstructure model shown in the photos above. I’ll post photos of the results.
Our Form 2s, on the other hand, routinely print beautiful models. The rare Form 2 print failures we experience normally indicate that the mirrors need some cleaning. Once cleaned, the printers resume producing beautiful models.
I remain hopeful that FL is resolving Form 3’s issues. There are features of the Form 3 I do find far superior to the Form 2 (optical cartridge, easier enclosure access for cleaning, bigger touchscreen, etc.) I am very anxious for the Form 3 to be able to produce sellable models like those we are get from our workhorse Form 2s. We want it and we need it.