Poor calculation of material left or used in 3L


I don’t “do” forums, but this morning felt driven to inform everybody how I feel about the 3L resin/cartridge “issue” I am seeing. (I am sure others will have seen this)

I am getting great prints, I print in mainly Rigid 4K and Tough 2K, so not the easiest end of the resin spectrum, but I need stiff and tough model parts for my high end clients.

So far, when printing in Tough 2K, I have had the machine tell me my cartridges are empty, when obviously not as I weighed them and had a total of around 30% left in the two cartridges. I am doing Rigid 4K prints at the moment, and a 21 hour print has just “paused”, as obviously there isn’t enough resin in the tank, but the machine thinks there is still plenty of resin in the cartridges (but they are both empty as I have weighed them to double check).

So the machine is just sitting there paused, and as Is I don’t yet have any spare resin (why would I need any as the machine was telling me I had plenty?) ultimately this will scrap a very long build. Up to that point the complex print looked flawless.

FL method of calculating how much resin has been used/left in cartridges is fatally flawed, as it is “open loop”, i.e. no way of knowing whether their calculated use is actually true (a very bad underlying “rookie” design mistake). Resin contents (a critical design/manufacturing parameter) needs to be in a closed-loop system, such that the machine knows, at any time, exactly how much is left in the cartridge(s). Doing this by weighing the cartridge is the only obvious way of calculating the volume (every type of resin as a specific and different mass per ml), but always constant for any given resin.

This is actually a show-stopper for users, as they either end up with expensive resin left in the cartridges which they can’t use (but have paid top price for) or they scrap prints as after an hour or so you can’t restart a paused print without a likely failure (but the machine is not showing an error message as it still thinks the cartridges have resin in them) . The printer gets into the “trying to fill the tank from an empty cartridge which it still thinks has resin in it” loop from, which it cannot escape.

FL support says to reuse resin left in “shown as empty” cartridges by simply poring it into the tank and using new cartridges, but that too isn’t a solution for that scenario, as it then just further messes up the “resin used” calculation, as FL don’t have any mechanism to allow you to tell the machine how much resin one has manually added to the tank!
If simply, one could take the cartridges out, weigh them, and then reset how much was in them, this would be a step forwards, but I guess FL don’t want this as it could allow people to reuse empty cartridges with 3rd party (much cheaper) materials. Personally I don’t want to do this, but the current situation is pretty dire.

This is a very big deal!


Complained exactly about that on the 3L thread.
I also had a print sitting idle for hours and hours (not even a warning or message) just because it was trying to fill the tank over and over with empty cartridges (which the 3L thought were half empty).

And yes, Rigid (both the 4000 and 10k) is a delight to print on the 3L as it is with the 3.
Other resins give mixed results as far as others reported it. May work, may not.

The 3L is still in beta in so many ways that it becomes irritating most of the times.


I too have ha issues with this. I actually tapped something under the sensor for resin level to get it to finish a print. When I did this it actually thought there was too much in the tank but allowed me to ignore the message.

I am not sure why it will still show printing when it is trying to refill but nothing happens. It should time up and give you options for canceling or pushing on.