Hi alexm,
Could you clarify: Does it only fail when you print direct on the base, and does the same part succeed when you print it normally on a raft with supports? From your post it sounds like the latter succeeds up to about the last 3rd of the print. What’s the struggle you encountered at that point? Did you orient the part identically in both tests (i.e. straight up and down)?
What sticks and what doesn’t? Do the first 20 or so layers adhere to the build platform, then nothing after that? Do the mini-rafts adhere, and do any of the lattice posts rising up from them print? Do you wind up with a silhouette or a pancake stuck to the LT tank? (I assume when you said “sticking layers to the cartridge” you meant something like that?) Any of the other symptoms described here (e.g. delamination)?
I’m trying to determine if you have a general issue impeding build platform adhesion (often caused by dust on the optics), or if there’s something specific to this part. Have you tried printing any other parts directly on the base? (You could try this graduated cubes test, it should complete pretty quickly). What about any other resins?
I agree the shape looks well-suited for direct-on-base printing (especially if you can tolerate some dimensional inaccuracy from compression on the end that touches the platform). The channels along the sides should act as “vents” to prevent any cupping issues.
Inspect the bottom of your tank for dust, clouding or damage. If there’s any wear, try moving the model to an area that’s still clean. Inspect the glass optical window of your printer for any dust and look through it toward the main mirror in the chamber to see if you notice any contamination.
You may also want to filter your resin if it has any chunks in it from previous failed attempts.
If the optics are clean, try adjusting your Z-Compression. Often times I’ve found moving the platform lower by a couple notches solves adhesion issues. Since you’re in a hurry, this might be worth a shot on your next attempt. At worst the print will just be a little more squashed at the bottom, and harder to remove. You can also take one of the prints you did on a raft and measure the thickness of the raft. If it came out significantly thicker or thinner than the “Raft Thickness” setting you used in Preform, it could further indicate some Z fine-tuning is required.
One more thing. I noticed some possible minor weirdness going on in Layers 16 through 35 when you preview your way through the slicer. There appear to be blue laser paths overlapped with areas already laid down in orange “support” structure.
Usually that’s the sort of thing seen if there are issues in the STL file, but since it doesn’t occur when I slap your part down directly on the base with no support structure at all, I don’t have reason to suspect your file. I think the artifact is being introduced by the “Early Layer Merge” feature, and it might even be innocuous (I haven’t paid a lot of attention to the quirks of that feature). But you might try humoring me and regenerating the direct-on-base supports with “Early Layer Merge” set to 0. I think that should be OK for your geometry. Double-check whether you wind up with any new red zones on that first chamfer, in which case you can add a few smaller touchpoints like the one I put in here to eliminate them:
Keep in mind Rigid is a more challenging material than others.
Also those exterior fins get pretty thin where they contact the build platform, and might be prone to breakage when you try to remove the part. If you do get a successful print, I suggest using a razor scraper to carefully detach them. Doing so while the print is still warm and fresh might be easier than if it’s been caked on for a whole day. There are lots of other tricks on detaching stubborn prints if you search the forums (e.g. letting some alcohol soak the edges, applying some heat from a hairdryer, even putting the platform in the freezer, I’m told).
EDIT: One last thing I forgot to mention - if you keep having trouble, open a ticket with Support. If you’re on a deadline, might be an idea to get the ball rolling on that sooner rather than later.