Curious why the Resin Tank Platform is Spring Loaded

I know it’s pretty ballsy to ask for proprietary design information, but here’s why. As I’ll detail in another epic post, I recently needed to dismantle my Form2 to clean up a resin disaster. Upon reassembly, I left the tank mounting platform untightened for a slight gap because that’s how I remembered it. However, when I inserted a tank of clear resin that was previously fine, the Form2 said it was Overfilled. Only when I tightened the platform screws all the way, thus lowering the tray relative to the level sensor, did it accept the resin level as it had before. However, experience tells me that if something is mounted with springs, it should have “play” for some reason, and tightening the screws all the way prevents that. The Form2 is currently printing fine, but still… am I putting something at risk by defeating the spring action?

Without these springs, the Z-axis would have a hard-stop. As soon as it hits the fully compressed springs, it will put a high force on the tank, platform and spindle. This can cause for example mechanical wear and missing steps from the stepper motor. You can actually see the tray going down during the first layers of a print.

I would recommend to not fully tighten the screws.

Yes, I’m not comfortable with them tightened all the way. In addition to your reasons, I’m sure this puts undue pressure on the PDMS layer too. I’ll figure it out. Thanks for corroborating!

You’ll want to open up a support ticket, as the machine will likely require factory calibration. The tray carrier (resin tank platform) is adjusted and calibrated for level sense, as well as for part adherence and accuracy.

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Point well taken! Although I must say I just had a print come out perfectly, and the stigma of the cost and work to pack and ship this beast from Romania and back compels me to save your offer until I’m positive I’ve done all I could here. I’m a consummate gearhead with an inexplicably advanced grasp of how mechanisms work, but more importantly, how they’re supposed to work when they don’t. I love to fix things, only slightly less so if I’m the dweeb who broke it. I “get” the relationship between the Form2’s screen-based leveling routine, with which the resin tray’s level-ness needs to agree, while at the right height for resin at the “Maximum” line on the tray to just trigger the photosensor. I eventually did all this intuitively and it seems to be working as well as ever. I strongly expected to have to at least adjust the Z-height of the platform, but not even! So either I’m that good, that lucky, or the Form2 is that forgiving. I’ll take any of them! Of course I will be keeping a close eye out for any change in that status!

Hey, I have exact the same problem. Cleaned up resin and now I am courious about the re-calibration.
It would be good if there is a diagnostic mode where you can lower the z-Platform to zero. Then you could reajust with a gauge or whatever - but sending it in for calibration is not a very suitable solution.

Is there a way to lower the platform by hand or manually by software etc.?


If the Form 2’s Z axis is built like the Form 1 / 1+, The Z 0 is at the top at the end stop sensor. The recalibration would need to be done at Z-7000 (give or take a few ticks).

I gather one could adjust the platform height with some care, time and the right gauges to get the height perfect, but I do not see FL releasing a how to for this.

I know if I have to take my machine apart where I would be messing around with those, I will be marking the position and counting the turns to remove them.

The screws are there for leveling of the tank relative to the build platform. So if you can find a way to measure the angle of the platform, you can angle the build platform the same way.

But… If you have this error, it’s better to contact support. They will help you and if it’s needed to take apart the form 2, they will have instructions to do so.

The thing is if there would be a possibility to move the z-axis manually then a calibration could be done in different ways.
Its not only leveling its calibration of absolute zero, too. Z-7000 is a good hint but not practicalbe - of course you could trun 7000 clicks by hand but … another way would be to dismantle the z-axis and connect a arduino with a pololu to move the stepper. A software solution from formlabs for manually moving to zero would be the best solution and easiest, too.

The 7000 isn’t clicks. It is machine code ticks. You can’t count the hard steps in the stepper and turn the screw 7000 times to get it in the right spot, I think. I never really thought about trying it…

Formlabs releasing a whole bunch of things like the schematics would also be great but that is never going to happen unless they are forced to. It would make self calibration, DIY troubleshooting, etc really easy for some, and it would be a really poor business decision. IMO…

I do not have a F2 and this is being spit-balled off the top of my head…

What if you took a new vat and build platform, Made sure your machine Z offset was at 0 (should be there by default anyway), start a print, pause it at the point where the laser starts to draw. This will place the build platform at Z=X. X really doesn’t matter other then it is the compressed starting point of the print. If we assume the normal compression is Y (I can’t think of what it normally is but say 1mm by default. *** I am guessing. Don’t assume the 1mm is correct, it is not…***), use a feeler gauge between the screw heads and the holder assembly they tighten up to. When you can get that 1mm gauge in-between, you have set the height as well as set the planes parallel to each other.

Please take all that with a huge grain of salt. I have no real idea if it will produce the results you are looking for. But logically, it should work. YMMV… I will not be responsible if the above destroys your machine or makes things worse.

The best option is to send the printer in for calibration and certification from FL that the printer is working correctly. It may cost a little but it is the better option.

Here’s a fresh print off the civilian-reassembled Form2. Pay no mind to the smears, that’s a botched clearcoat job on the back surface. You can see it’s as good as it ever was!

I understand and appreciate the trained engineers out there who insist this is impossible without oscilloscopes and electron microscopes. That’s what your training told you, by it’s very nature. But consider an analogous situation with filament printers: today you calibrate the stepper motor drivers with a voltmeter. But go back to the early days and you know what Makerbot’s official guide to stepper calibration was? “Turn the potentiometer until the motor SOUNDS RIGHT”. This may be where my level of skill is, but it clearly has validity when done right.

I’d really love to see Formlabs release a procedure for users to attempt manual field calibration of the build platform height. Even if it’s a bit of a dice roll and not as good as a full and thorough factory calibration.

I had a Form 1+ that had to be sent back to the factory to replace the Z-axis linear bearing. It was quite expensive and took a while. I would have been happy to have them ship me the parts and take a shot at doing a repair here before resorting to sending it in.

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