Pre-fill tank


Anyone else frustrated when you start a print that should finish just a little before the end of the day, except it doesn’t finish in time because that the printer takes an hour to fill the tank before beginning the print? Or, you want to print a small part that should finish in 30 minutes and you know there’s plenty of resin in the tank, but the printer still takes an hour to fill first anyway? We’ve got a Form 3 now, but I remember a similar frustration with our old Form 2 as well.

Why fill at the beginning of the print? Why not fill after the previous print has finished and the printer is sitting idle, that way the tank is full and ready when you start a new print?

It sure would be nice to have at least one of these options to solve this:

  1. Add an on-demand tank fill option - maybe Prime does this?
  2. Pop up an option to refill the tank after the previous print has finished. (And maybe initiate this automatically if no user input and the printer is idle for a few minutes?)
  3. Add an option to skip filling when starting a new print (and preferably have this option pop up immediately, so we don’t have to wait for heating to complete)

I think this has been requested by others in the past, but those requests have been closed for years. If you would also like to see this feature, please like or reply to this thread.



I don’t have an issue with this. It makes sense to do it at print start.

If you want save some time you can always fill up the tank manually before you start.

I’d love if they could make this happen! I too hate that it takes forever to fill before a print. I end up just manually filling to about halfway of the mixer (maybe a tad bit less) and its good most of the time. If you do manually fill, do it after the first wipe pass or else there is a possible chance that it can overflow on the first wipe pass. Or you can trick the system by getting a stick and holding the resin level float up on the resin measure wipe (when wiper goes left during filling process). Although there are workarounds, I’d like to see a one touch fill and prime feature to prevent manual intervention and user errors. But sadly, this is more of a “nice to have but not needed” feature because I feel that many people don’t mind or think that its a big deal.

Thanks for the support Altavis!
I agree this is a “nice to have” feature since it wouldn’t affect printer capability. But I do believe that plenty of people care about this whether they realize it or not - I mean who doesn’t want their parts to print faster?

I think it’s more than nice-to-have… In fact I’d go as far as saying it’s pretty essential, that and not to abort filling and restarting filling all the time when the mixer arm moves. In a cool environment ( <20 deg C ) it can result in several DISPENSE ERRORs (and with no way to remotely resume) - clearly this is not as intended otherwise why error?

It should be triggered off the PRIME button. If you know you’re going to be printing, you should be able to prime the printer in advance. Priming should perform the pre-heat and then fill the resin tray and then hold temperature until you either cancel the priming or actually start a print.

I would leave my printer in this “primed” state all the time. Re-prime it every time a print completes. I don’t care about the few Watts of electricity that’d be needed to keep things warmed up. And my print jobs would start right away as opposed to 1.5-2 hours after I try to start them, as I wait for the printer to sloooowly bring its temperature up to target (the printer lives in a basement workshop that’s generally in the mid/low 60s) and then dribble in the resin to fill the tank…


I agree that the proper time to check resin level is at the end of a print, and to fill the tank then, or just a few layers before the print is finished. That way if you’ve got another platform ready to go, you’re printing immediately, instead of the best part of an hour later.

There’s always the case where you’re going to change the resin and tank after a print. So you’re lifting and storing a full tank rather than one that’s probably nearly full.

I can’t see the problem with that.

A “primed” printer should be just that; ready to start immediately.

ready to start immediately.

Pretty much the textbook definition of “Primed” right there. :slight_smile:

And don’t get me started on why the remote monitoring feature doesn’t actually tell you what the printer is doing until it has actually started to print. So the preheat and fill operations just look like the printer isn’t doing anything for an hour before each print starts. The dashboard does report when pre-heat and fill fail, but not when they’re underway. What’s up with that?

I’m an ex-software engineer. I know this stuff isn’t hard to do. I haven’t heard anyone from FL arguing that they’re bad ideas. I’d really be thrilled (hint hint) to actually see some of these recurring user suggestions implemented.

100% ack to dcaplan’s suggestion!

+1, this is a great suggestion

Im having loads of trouble with mine also, If the cartridge is below 1/3 full, it stops pouring, instead only dripping when the valve is open. I imagine this is because the low-cartridge head pressure isn’t enough to push the thick resin though the barely-open valve. There is definitely something amiss with the form-3 valve mechanic; my form 2 never had this problem

Thanks for the votes everyone!

I feel your pain with the Form 3 fill actuator. I just had a Draft print estimated at 30 minutes actually take 3 hours because it errored out during filling. When I pressed “retry” it just started printing immediately without filling any more anyway!

All the more reason to give us the (probably very easy) software option to fill on command.

That is absolutely a must. I am pretty new to 3D printing, but the first frustration I was hit with, is that I skipped the moment of pre-filling the tank with new resin. Then I started a new print and when I noticed, that resin, instead of lowing in nice stream, it started ‘dripping’ in. This would take few days for the tank to get filled!. What would be my frustration, if I wouldn’t actually look at this? I have seen the ‘prime’ option, but I don’t think this do much of priming really.
I am 100% for none messy, open the valve option during priming.

If the resin is dripping in then loosen the cap some to “burp” the cartridge. There’s an air lock in the bottle. This can happen a lot when it’s suggested that you shake the cartridge before putting into the machine.

Like “allonscale” suggested it’s beneficial to fill the tank some before starting your print. I have done this on most of my prints and they start very quickly.

Some bite valves appear to be a a little faulty. When I got one that didn’t flow, I jammed a Xacto #11 knife in to the slot to open it up a bit. You have to be careful that you don’t damage it so it doesn’t seal anymore so I don’t recommend this unless you’ve got no other choice. But done properly it does fix the dripping bite valve problem.

Also, if the cartridge was new and it was stored upright (valve down) , maybe it needed it some thorough shaking (like: viscosity at the bottom to high?)

Good idea, would love an option to force fill! It is annoying to have to wait extra long for a part when running a fresh tank of resin.

A workaround to this would be to manually pour a bunch of resin into the tank (by unscrewing the cap of the resin cartridge and holding it upside down over the tank) so that it spends less time automatically filling it with that skinny little stream of resin, but I’m not sure if this would completely throw off the “remaining resin” calculator which gives an estimate for how much resin you have left in the cartridge (sort of like printer ink cartridge levels). Not that the calculator does anything other than give you a visual estimate, but it’s still useful to know when you might be close to needing to reorder more resin.

Thanks everyone for the comments and suggestions!

For those that mentioned pouring resin into the tank manually, Formlabs actually recommends doing this for brand new tanks to reduce the fill time. Personally I’m on board with doing this one time for a new tank, but NOT before every print. First off, manual filling is too error/damage prone for a printer that has multiple users, especially when there are no markings for how much to fill. Second, FL has obviously invested significant resources into the the printer’s automatic fill system with level sensors, fill actuator, cartridge design and manufacturing, system design, programming, etc. If the users of this system are bypassing all of that by manually filling the tank then what is the point? The automatic fill system is a selling point for the machine - it should be programmed appropriately to meet the needs of the user. All the hard work has already been done, FL just needs to add a button for the user to manually trigger (or skip) filling.

I mostly use black so I keep the tank full from the last print and it only takes a few minuets to start the print. I wonder if your cartridge has a sticky valve. If you turn the cartridge over and squeeze the valve that may fix it. I have cleaned it one time with solvent when I did see it was stuck.

Don’t forget to close the top cap before inverting the cartridge.

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