Unable to print on certain areas of build platform

Hi , I am having fail prints on certain area of build platform. I have replaced a new resin tray vat and new resin cartridge . I am using the latest. Preform software and also the lates firmware update. I also ensured the platform is level.
Most of the failed prints occur around the middle of the build platform. Prints end up on the resin tray. Nothing sticks on the platform. Yes I have combed and filtered the resin each time when this occured. Other parts around the side parameter seems to be working fine. I have also tried lowering the build platform by ~0.01mm on the Z axis. ( this still does not explain why other areas has no issue )
Any help will be most appreciated! Thank you.

Warm regards

Check if your build platform is hollow.

I’d look at dirt on the optical surfaces - check Formlabs’ advice on cleaning, in this order, the top of the laser window underneath the tank, then the underside of same window plus the mirror, then the galvo mirrors. Try a new print at each stage.
I’ve had this kind of problem and it solved the issue.

by hollow I assume you mean it’s dented or uneven ?.. I did try using a metal ruler to check the flatness. Seems ok.

I did notice some smudges on the surface, I have since cleaned it. In regards to the mirror and the galvo mirrors… this is what I am worried of messing it further. Not sure if I need support or tech support to do this. Hope Folks from formlabs can advice me on this,

The mirror’s reflective surfaces are on the front of the glass, not the back. They’re easily damaged. There is a specific procedure for doing it, and specific materials are required. Formlabs will send you the instructions if you ask (though it might be posted in the forum someplace, it’s a pretty common issue). I cleaned mine once, wasn’t that big a deal. Hardest part was satisfying myself that there was no dust on the mirrors or the underside of the glass before I put it all back together.

Yes, smudges can be a problem, and Randy’s correct - you have to follow the instructions or you can damage the surfaces. Having said that, it’s pretty straightforward. I keep a battery vacuum cleaner specially for hoovering the insides and removing dust, assuming you need to clean the innards.
Give it a go and try the print again.

Thank you guys for the suggestions. I did try to do some print test to access which part on the build platform that has the problem of the print not adhering to the surface, Attached an image to show my result.

  • Considering the other prints are flawless except the center… I would conclude the galvo mirrors are not the source of the issue
  • I did ensure the surface of the laser window glass is spotless and the build platform is not warp or anything
  • I cleaned the build platform with IPA to ensure there is any residue like oil etc…that is causing the detachment

As we speak , I am doing another test again , large chunks somehow falls off from the center area half way during the print. … Hmmmm… I donno what else I can do…

Hmm… I am stumped.

would you suggest lowering the Zaxis of the build platform lower?. 0.5mm would be a good number to start? Thankis!

No, that can crack your tank causing leakage.

I had a few build platforms that were hollow. With a ruler you could just see light under it.
It won’t hurt to check again and perhaps sand the platform flat.

I did notice a small gap when I place a ruler from corner to corner. But how did this warping happened. It was printing alright just before I updated the firmware and the software.