In the middle of air

so here is how last update of preform made supports, after 10 calculations same…

Hey, I’ve seen that before!

It happened to me last year on an older version of Preform. I can’t remember all the detail, but the model it presented on may have had some malformed geometry Preform didn’t like.

I still have the Form files, but when I tried to use them to recreate the issue it seems it no longer occurs for me in either Preform 3.2.1 or the latest 3.2.2.

For what it’s worth here are some more pictures:

Also encountered a support to nowhere:

I found the image below amidst my notes which made me think malformed STL, although when I skim through with the slicer on recent Preform versions I don’t see the inversion present anymore:

I thought I opened a ticket with Formlabs at the time but can’t locate it.

Out of curiosity did Preform prompt you to Repair your STL when you imported it? If you walk through the slicer do you see anywhere the layer footprint “inverts”?

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I was on last preform version, then I switch back to 3.2 before support changing but same it catch for something in mid air, I have problematic pillars but everything else was in polygons and its fine, ok at least good start to know its my model problem not preform

First thanks rkagerer for your reply. I follow your reply and separate my model (cca 1 000 000 polygons) in groups that looks like problem, arches, pillars-column (they are problematic really) fence, and then started to import one group by one with rest of building in preform. Preform calculated model with every group ok. Then export whole model again and import in preform and it calculated without star supports again, so everything is fine now. What I think is a problem where I lost hours yesterday, I have problem in model, so when I import with repair it make star when I import without rapair it doesnt have star supports in mid air. So I have to fix my model although i have architecture model that some parts are intersecting with others, have no idea how to solve that. Only solution is to make again whole model as single mesh and that takes hours…

I know, it can be difficult to track down and correct the source of STL issues. Preform has gotten more tolerant over time but it’s not perfect.

Cleaning up your model at the source like you’re doing will yield the best results, but if that’s not feasible you might try something like the Make Solid or Remesh functions in Autodesk Meshmixer. Or an STL repair tool designed to produce watertight meshes.