Thanks for all of the suggestions. Ultimately with this amount of fine detail, I will either go to a solidscape or adjust the design a little so it can be printed in halves.
That being said, this was a really good thing for me to look at because it allowed me to see the limits of the printer and understand how it works. I was printing at 25 but even so due to the steep inclusions of detail, no matter which way you turn the design you end up with details that become “islands” when they are sliced. If the islands do not have supports they fall off. So while the whole print doesn’t fail, the unsupported island do not get fused with the rest of the print. This is what was creating the area of low detail.
Just for sake of learning, I used the level slice tool to the right side of the Preform window and tried to manually add supports to these islands. I tried various orientations. I used the smallest support size. I printed the “best” version and it came out rock solid. But because there were so many supports, I obliterated the detail of my print. I kinda expected this but I just wanted to see for myself.
For the sake of the other newbies on this forum, I’m pasting in the Formlab’s Support response. It was quite helpful.
I appreciate the Dropbox link; I grabbed your .form file and took a look. The ring is very intricate and beautiful, and you’ll be happy to hear I think I’ve discovered the source of the roughness on the underside.
I hadn’t quite realized the scale from your photo. The details and textures of the surface are very small—so small that many of the tinier features are around the minimum size the Form 2 can effectively print. As the upper side of your model shows, the printer can still create those features beautifully. However, it’s very difficult to attach supports effectively to such an intricate surface. On the underside, many of the finer features of the part are unsupported—as they print, the outside tips and ridgelines print in layers before the main body of the ring starts, and on many parts of the underside there’s nothing holding those details up. I attached some images showing what I mean.
It’s not easy to remedy this situation. You’ve already noticed that placing supports on features like this, which are smaller than the support point, obliterates them—but if they’re hanging below the body of the part and not supported, then they won’t be able to print in the first place. Unsupported sections will be created in the tank, but without anything to peel them off they’ll just stay stuck there and get brushed away by the wiper. (You may still have some cured particles in your resin tank; I’d consider filtering the resin so that these don’t disrupt a future print.)
I think your best bet is to re-orient the ring so that the setting is at the highest point. I’m afraid the underside of the part will still tend to lose any of these very very small raised features, but you can point the least-crucial section of your part towards the underside.
Declan Geoffrion Scannell