This is why I am removing the almost empty cartridge before leaving. I have run several 40+ hours, 700ml+ prints in Grey Pro back to back recently. After the first one, I launch the 2nd one with the “old” cartridge, I know there’s a bit more than 300ml left, and I could probably leave the printer and switch the cartridge in the morning but I want to ensure that the print doesn’t pause for a few hours so I put a new cartidge in. When I come back in the morning I either let it run or I put the old cartdidge back in to continue emptying it knowing I’ll be there if there’s an error.
This is not ideal but it’s not a deal-breaker by any means.
What has been asked of Formlabs many times in the Feature Request category is for the printer to not stop mid-print if you already have overriden the “low resin” warning at the begining of the print. With the cartridge level being an open-loop system there isn’t much more that can be done.
IMHO tricking the printer into thinking the cartridge is full is a bad idea. For one it will try to continue to dispense resin and will eventually throw a “cartridge error/empty” message, and if it doesn’t do that the tank wll not be filled enough and for a big print there’s a considerable chance the resin won’t be able to flow back at the center of the tank after the wiper’s movement… leading to a failed print.