I have been using the Formlabs Form 4 for nearly two years and have generally had a stable experience. However, I have encountered a recurring issue related to resin usage and print initiation.
The printer appears to manage resin levels by maintaining approximately 250 ml of resin in the tank during operation. Over multiple prints, this results in the cartridge being gradually drained while still leaving a usable amount of resin in the tank.
The issue arises when the cartridge becomes empty. Even when there is around 200 ml of resin remaining in the tank, and the next print requires only about 50 ml, the printer refuses to start. Instead, it throws Error 1.9.6 (Not enough resin to finish print) and Error 1.9.22(Cartridge is empty).
I have attempted the following troubleshooting steps:
Despite these changes, the issue persists.
I would like to know whether others have encountered similar behavior. If so, what methods were effective in resolving or working around this limitation?
1 Like
I had a similar issue trying to change a tank over from Tough 2000 V1.1 to V2: How to transition material version in a Form 4 tank
My workaround was to clip a small clamp to the top cap of my empty bottle so it weighed the same as a partially full bottle (be careful opening the lid if you do this - I kept hitting the clamp because I forgot it was attached). You still need to wait ages for the slow filling warnings to appear and eventually allow you to start printing despite slow filling being detected.
I think the logic that formlabs has is that you would just open a new bottle. We are printing regularly at the moment, so I don’t worry about resin sitting in the tank for extended periods but perhaps that’s what’s a concern for you? Perhaps if you share the reason for not opening a new bottle it might help identify a different solution.
1 Like
@smerrett Thank you for your response.
The core issue arises from resin utilization efficiency. When purchasing one liter of resin, it is reasonable to expect that at least 90% of it should be usable. It is understood that the machine must retain a minimum amount in the reservoir to prevent print failures.
However, the current behavior creates a constraint where effectively two bottles are required to fully utilize one. In practice, only about 75% of a single bottle can be used, even in cases where the remaining resin is sufficient for smaller print jobs. The system restricts usage despite technically viable print conditions as mentioned above where I am unable to print a model which takes 50 ml even when there is 200ml in the tank. .
This design appears less aligned with operational safety and more indicative of an unnecessarily restrictive or inefficient usage model.
Additionally, consider a material change scenario, such as switching from Grey V5 to Black V5. If approximately 200 ml of resin remains in the tank, the expected handling process is unclear. It is reasonable to ask whether this remaining resin can be safely transferred back into the original bottle for later reuse.
Even if that step is performed, the system behavior introduces another constraint. At the start of a new print, the printer drains the remaining 200 ml from the cartridge and triggers the same minimum-level error. This creates a loop where the residual resin cannot be practically utilized without introducing a new bottle, effectively forcing additional purchases to access material that has already been paid for.
The times where you need to change resins in a tank, such as between versions or resin types does create “overhead” wasted resin which cannot be used. The most efficient way to use the resin is to use a lot of it over time and never change the use of the tank from one resin to another. This is obviously costly in tanks and wipers which you ideally want to assign to one resin type and keep assigned to that resin.
I did manage to get down to a really low level of printing using the method of ignoring the warnings that eventually got displayed with my weighted bottle workaround. I ended up with a thin film of V1.1 resin on the bottom of the tank before switching over to V2. So you could definitely get down to around 100 ml or less with this approach. Just make sure your printer tank is really well levelled!
Hi everyone, thanks for bringing up the question!
I’ve checked in with our technical team to clarify the reason for this behavior. Generally, the printer requires a larger amount of resin than what is needed for the model itself to guarantee a successful print.
During the inter-layer routine (the peel and squish), the resin needs to flow back fully across the tank within a short window. When the resin level is too low, factors like surface tension and printer tilt can slow down the re-coating process or prevent it entirely. Keeping that extra volume in the tank ensures the recoating remains consistent throughout the build.
I hope this explanation is helpful!
Hi Sophia_M,
Thank you for the clarification.
If I understand correctly, approximately 200 ml of resin remains effectively unusable toward the end of a bottle. This occurs regardless of whether I switch materials or continue using the same resin, since the printer requires a minimum volume to ensure proper recoating during the inter-layer process.
From an operational standpoint, this creates a cost inefficiency. At a local price of about $127 per bottle, the unusable 200 ml translates to roughly $25.4 per cycle. When running a business, this loss has to be absorbed or passed on to customers, which makes pricing less competitive and introduces a recurring overhead that is difficult to justify.
I truly believe Form 4 is a wonderful machine and we have been able to get some excellent quality prints, but this specific constraint impacts cost control and scalability. It creates a situation where both the business and the end customer are indirectly penalized.
It may be worth considering a user-controlled override option for the low-resin warning at around the 200 ml threshold. This would allow operators to decide whether to proceed with a print based on their own risk assessment. If a print fails due to insufficient resin, the responsibility would rest with the user, but it would provide greater flexibility in managing material utilization.
I hope the team can explore potential solutions in this area.
I think Sophia is saying that you need some buffer amount. You have settled on 200 ml from your original post, so let’s use that in an example. Say you are planning to print the same resin and keep it in the same tank. You buy 1000 ml (1 litre) of resin in a bottle and insert it into the machine with an empty, new tank. The Form 4 assigns your resin type to the tank and fills it when you perform your first print. Let’s say you are printing your model which consumes 50 ml in solid volume. In fact, for ease of calculation, let’s say your solid model volume is 45 ml but you end up with 5 ml per model printed in liquid resin stuck to the build plate and the part-cured resin, bringing the Total Resin Per Model to 50 ml.
From your first bottle, you print as many of this model as you can. When the bottle is empty, the Form 4 lets you print until there is 200 ml left in the tank before it starts warning you that you can’t print because you have insufficient resin left. At this point, your first 1000 ml has only let you consume 800 ml because 200 ml is left in the tank. You have 16 prints of your model for this 800 ml. Ignoring the wasted resin that is liquid, the tank buffer is causing you 20% volumetric/cash loss on your first bottle purchase.
Now you need to keep printing your model, so you buy another 1000 ml of the same resin, put it in the Form 4 and keep printing. You don’t need to fill the tank this time because it already has resin left in it. So all 1000 ml is used in printing and you get 20 of your prints. Now you have 36 prints from 2000 ml, so your wastage due to the tank filling is now only 10%.
Then you buy your third bottle and keep printing the full 1000 ml from it - because there was still 200 ml in the tank when you finished the second bottle. The same goes for your fourth bottle. The wastage due to tank buffer is now 5% because you have been able to print 76 models from 4000 ml (against an ideal of 80 prints from that amount of resin). This continues if you are still using the same resin in the same tank until the wasted amount due to the tank buffer is a small percentage of your total costs and it ceases to be a significant concern.
You can complain that it is a loop and yes, you cannot use all of a new type of resin if you are putting it into an empty tank. It is expensive to “try before you buy (in bulk)” but once you know which resin you want to use, it only hurts if you print relatively little quantities of resin or happen to need just less than one bottle for all your printing. But I think this doesn’t apply to the majority of Form 4 users.
What are your current resin consumption rates like? How much resin does your printing typically consume over the course of a month or a year?
2 Likes
smerrett - I largely agree with your point, and I had overlooked the amortization aspect. That is mainly because, as a company, we do not use the Form 4 primarily for batch manufacturing. Our work is more along the lines of unique problems requiring unique solutions, so we need the flexibility to use multiple materials as and when required.
While I understand that some materials require a separate tank or even a separate ecosystem, for resins within the same family, such as White V5, Grey V5, and Black V5, we would prefer to use the same tank because it is more cost-effective.
Frankly, this issue tends to arise only when a particular resin is about to run out and we want to switch materials. That is why I said that, over the last two years, we have had very few issues with the Form 4 apart from this one.
It may be worth considering a user-controlled override option for the low-resin warning around the 200 ml threshold. That would allow operators to decide for themselves whether to proceed with a print based on their own risk assessment. If a print fails due to insufficient resin, the responsibility would rest with the user, but it would provide greater flexibility in managing material utilization.
In my experience described there is a user override option for the low resin warning - but I also combined this with a weight to trick the sensors into thinking I had resin left in my bottle but it was just dispensing slowly, rather than the actual case that it had run out of resin. You could try weighting your empty bottle and see if you get the prolonged (and tedious) period where it tries to fill, warns that dispensing is slow but eventually allows you to proceed at your own risk after clicking through perhaps a couple of screens to accept this.
I agree it would be far more convenient if this could be fast-tracked for someone deliberately trying to drain a tank through printing and is happy to bear the consequences. When I switched materials there was almost nothing left in the tank and I printed a cleaning sheet which took care of the thin layer of resin left on the film. So you can print down to quite low levels viably if you are careful.
1 Like
Thank you for the information.
If I maintain a constant baseline of ~200 mL of resin remaining in the tank, would that allow me to fully utilize a new 1,000 mL cartridge without risk of depletion during a print?
In other words, is this approach valid:
-
First cartridge: print ~800 mL and leave ~200 mL in the tank
-
Second cartridge: with that 200 mL baseline, print the full 1,000 mL from the new cartridge
Please confirm whether this method is reliable on the Form 4, or if there are still limitations that would prevent achieving full utilization of the second cartridge.
Thank you,
@Eluna32 Yes, generally this is correct - see the explanation @smerrett gave above. If you continue printing with the same resin, the extra amount of resin you need to have in your tank for a successful print process “carries over” to subsequent cartridges of resin, instead of you needing to reserve some resin from each cartridge.
Another small factor to take into account is that the build platform and printed parts are usually covered with some amount of liquid resin after printing, which then gets washed off, so this resin is technically not used to print parts. However, this is usually a negligible amount; to minimize it, you can leave the build platform in the printer a bit longer to ensure as much liquid resin as possible drips off.
Hope this helps!