How to correctly re-calibrate the projector


I want to re-calibrate my projector focus; I’m just not sure the easiest way to go about it.

I’ve seen several posts about calibration and know how to change the focus using the screw in the back of the printer but I was wondering if there is a written ‘factory calibration’ procedure that can be shared now that Autodesk isn’t producing the hardware anymore.

There must be some trick or tooling used since the best I can come up with is to lay a piece of paper on the tray with the ‘showcal’ image projecting.
How can I be sure the image is actually the correct size?
How do you tell if everything is in the correct focus - and not just slightly blurry which would have a big impact on fine resolution?
Do you use microscopes, eye loupes, calibrated glass scales, image capture…?


Yes, do tell pls.
In an in-person discussion, I was told it is being done digitally.


The difficulty I see is that there is no way to calibrate the focus to the actual trays, as you have to have the machine completely apart to access the focus ring. So how did the factory actually calibrate the focus to the tray? I know it’s close, but when guys like me want to squeeze every pixel out of the thing with absolutely the best dimensional accuracy, close isn’t good enough.

I suppose I could fabricate an adapter that grips the focus ring and is attached to a screw driven lever that could be accessed from below (by drilling an access hole).


I hope I’m not too late to answer this. I just discovered this website.

The Ember printers were calibrated digitally, but this calibration was for the projector relative to the base. The tolerances on your specific resin tray, vat support plate, and window will all affect how accurate your assembled printer truly is.

To calibrate the projector you will need to disassemble your Ember once to loosen the screw holding your projector in place. It is just to the left of the projector lens and should be pinching down in a slot on the projector housing. Once this is loose, you can calibrate your projector with a 2.5mm hex wrench on the long bolt located below the back of your projector. Also great is that this bolt is accessible while the printer is assembled so you can modify the calibration on the fly.

As for calibrating to perfection, your best bet is to calibrate with paper from the window of your specific resin tray (clean of course). If you’d like to build a contraption that detects the showcal image line at exactly 64 and 40 mm you can, but a drawn rectangle on paper can get you pretty darn close. The best thing to do once you calibrate the focus is to print and measure. The amount of light getting through the projector lenses and PDMS window can vary from printer to printer, not to mention your material and print settings will have a large effect as well. So of course use the tray, material, and settings you prefer and then measure the produced print in relation to the digital dimensions and alter your image scaling from this.

I’ve done high tolerance stacked prints on Ember and we used this procedure to get extremely accurate parts.
Let me know if I didn’t explain anything well or if you have any questions.


Thanks for taking the time, and welcome!
There are several of us here that are looking for the most accurate setups, and your information is one more step in that direction.