Print time inaccuracies have been reported several times, two of them being
Issues arround resin sensing have been reported too.
I am under the impression that Formlabs is in a kind of a dead end with the resin sensing because it’s a mix between open loop and closed loop systems with very slow sensors and now they have to solve a bad hardware design decision with only being able to act on the software side…
The resin level in the cartridge is an open loop system so they are very conservative with the estimate (which leads to early / frequent / repetitive warnings) and the resin level sensing int he tank is very slow. Both of these issues put together make for a very slow resin sensing loop which has to be performed very frequently when resin level is estimated as low in the cartridge, to be sure to avoid not having enough resin in the tank.
It would be as easy as the second time you’re asked “this cart is either closed or is empty, continue?” and if you click YES, instruct the machine to NOT do any further attempts to sense resin or refill…as easy as that.
If you stop refilling, you have the risk that there will not be enough resin in the tank to finish the part (risky). If you choose to continue to refill, you have to check the level of the resin to know when to do so (slow), and you have to refill more often than when the cartridge is full because the resin doesn’t flow out of the cartridge as fast (slow again).
Formlabs takes the Apple approach : the user is stupid and we prefer to remove choices from their hands rather than let them make bad decision (which in this case would be to bypass the refilling operation and not have enough resin left to finish the print).
I agree that we should have the choice to take the risk but I don’t think Formlabs is willing to allow that.
The real solution would be to have a closed-loop measurement system on the cartridge (weight measurement would be a simple way to achieve that), a faster way to measure the level of resin in the tank, and maybe a deeper tank to have more resin in it thus allowing for less precise and less frequent dosing.
Formlabs knows the approximate level of the cartridge. It should be pretty easy to adjust the fill time to account for the cartridge level (longer bite valve opening at the end of the cartridge).
We had a lot less issues before Formlabs changed the calibration to empty the cartridges sooner (people were running third party resins). It looks like they pulled things back too far and now we have to suffer with these problems.