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Cannot find scale fiducial center

I was cleaning the LPU glass according to the formlabs instructions and when I was done the printer needs to recalibrate the LPU. Towards the end, it gave me this error saying that it cannot find the scale fiducial center.
Does anyone know what that means?

Thank you,

I don’t know exactly what it means, but it sounds like its looking for some sort of marker that helps it determine what the laser is targeting, at various distances from the glass.

But I doubt I’m being very helpful. I think you should open a support ticket.

Thank you
I have submitted a support ticket, I’m still waiting to hear from anyone.

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Hi Antonio,

How did you solve the issue.
I have the same problem.
Your advice would be appreciated.


Hey JC,
I had to get in contact with FormLabs Support to resolve this issue.
Basically, they had me take photos of parts of the printer and then ended up sending me a replacement part and I performed the replacement.
Reach out to support.

Thanks, Antonio.
It sounds some parts are perhaps damaged.
Have a great day!

I too have an issue with the LCU after doing a cleaning. I followed the directions from support to clean the LCU and had the following ERROR: Could not execute initial home: Could not run OM post replacement: false positive fiducials found.
I’ve reran the replacement wizard a few times with same error after doing so.
It’s a Form 3 with FW version rc-1.6.8-588.
Any help with this would be greatly appreciated.

Issue resolved, turned out to be needing a FW update. Was used to the app telling me that update was required and have not been doing manual checks…My bad, but we’re back up and running.

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I am having the same issue: could not run OM post replacement: failed to associate the fiducials with grid.

Restart lpu replacement wizard or contact formlabs supporrt.

I did the wizard, i checked the fw and everything is ok. I just cant print.

Issue resolved : remember to put the thumb screw the first one.

I have the same issue, was cleaning and laser wont recalibrate. I’ve had multiple errors all related to the fiducial center. The latest is this error below:

‘Could not run OM post replacement: duplicate fiducial detected’.

I have all software/firmware updated.

Antonio, do you know what part they had you replace after you took pictures?



I have this exact issue. Cannot find fiducial center, my printer won’t print anything at all. I did the exercise to reset the LPU and clean the optical window with PEC pad because every print was failed despite a new tray and three different bottles of resin. Wiper checked, filtered resin, I did it all. Updated everything…I just can’t get this thing to work.