Resin sensor error again and again!

the Form2 is running INSIDE a steel cabinet, inside my office space. while the temperature varies a little bit- from 68 to 77 during the course of the day, that is within the advertised operating range of the printer. The printer also has its own internal heater to maintain resin temperature. and being inside a cabinet ought to make it easier for it to maintain temperature.

While temperature was one of my first considerations, i have seen no correlation between its resin sensor error behavior and overall room temperature… its as likely to stop printing i the middle of the day when its moderately warmer, than it is in the middle of the night when its moderately cooler,

At no time is it at a temperature that is not comfortable for ME to be in the room with it.

And my position that any senor system that would require controlling the room temperature within a just a few degrees is STILL a design and engineering failure… not operator error.

if the thing can not reliably print in an office environment… then its not even up to the product standards of an inkjet printer.

so far their only answer has been to send me an instruction sheet on how to ‘tighten’ the sensor level plate screws on the bottom edge of the sensor plate.

but they were NOT loose. they were actually tighter than the level of torque the white paper recommended,

the intermittent and capricious nature of the errors leads them to believe that the sensor plate is not properly grounded.

And that would fit in with your temperature suspicion, as minor changes in temperature could be causing the ground being lost with slight expansion and contraction of metal parts.

however- others have reported that adjusting these screws had no effect… and I would point out that a bad solder joint or poorly made connector between electronic components could just as easily form a super temperature sensitive “switch” in the ground state of the sensor.

Either way… its a bad engineering design or a bad assembly.
Formlabs needs to address this as a great many users are affected.

out of 7 prints i have run since I bought the thing… I have had exactly 3 print without spurious sensor errors causing flaws in the print and major delays.
that is unacceptable for any productive tool.

I finally broke down and tried open mode, just for the purpose of trying to finish a print. It worked like a charm…PERFECT. That makes this sensor issue just that much more frustrating. Because of this error, I have wasted over half of my clear liter of resin due to failed prints. I attempted to allow the machine to try to correct the sensor error on my previous print. after nearly 24 hours, no luck. Every time the machine would try to resume, the error would kick it off again.

I have been able to complete 2 prints out of about 10 legitimate attempts. I’ve successfully used about 100mL of resin. Due to sensor errors, about 400 to 500mL have been wasted. Quite a pricey problem to have straight out of the box. I’m wondering if Formlabs would actually consider replacing my wasted liter of clear resin.

Touching the printer icon on the touchscreen will display the temperature the printer is working at.
Mine is inside a wooden box that is insulated for sound. It regularly works at 38-40C and has been known to go up to 44C. Given the time your printer takes to recover from the errors I would suggest that you cabinet is too well insulated and needs to have more ventilation. Perhaps running a print with the cabinet door left open might tell you whether the error is temperature related.

I had the exact same errors and experience. Did you back out the 2 grounding screws and re torque them?

How I fixed the resin sensor error (hopefully for long)

We had the same troubles with a 3 weeks old printer. First it happend just once, then after updating the firmware the error showed up more and more often. After the next (latest) firmaware update it suddenly worked but after 4h (of 9h) it stopped. Since then it didn’t want to start at all without the resin sensor error.
After asking my local support they sent me the instruction for tightening the screws, which where perfectly tight already.
BUT our printer is printing again because in the e-mail they also asked me to push down the frame (where the tank sits on) several times. There are 4 springs. So Push the two in the front down (where the black srews are) and the the ones in the back. You can push quite hard until you feel the stop.

And IT HELPED!
I haven’t seen this advice anywhere else so I hope this will also help others.

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Yes- but now my printer won’t print because the “cartridge” has " Worn Out"… despite still being 1/3 full. So I can’t run a test because I ALSO have not received the two additional LT tanks I ordered with the printer.
Waiting on a replacement cartridge of durable resin.

When you say you HAD the same error- do you mean you no longer have them? If so, how did you get rid of them?

I have tried it with the door open. I have tried it with the lights on and with them off.
I have had it stop at 20c and had it stop at 30 c.

the cabinet is steel, and has no insulation. its whatever temperature the room is.
The fan moves 120 cubic feet of air per minute thru a cabinet that is 26 cubic feet.
I have tried it with the fan on low and the fan on high.

But beyond that, I am not the only person having this problem. LOTS of users are suffering the same problems and they have their printers in all sorts of different setups.

this is a HARDWARE issue. EIther the sensor is faulty- its improperly installed, or there is some other sort of intermittent electrical fault in how its wired.

Or- its simply a bad engineering design.

And I realize I could probably make the problem go away with OPEN mode… but I run 15 and 20 hour prints- hand filling the tank with cartridges that are not designed for hand dispensing is NOT the printer that I paid for.

formlabs needs to FIX this problem.

If the screw thing fixes it, great.
if not I’ll try the spring thing Biogear suggests…

But just the same- those remedies are BOTH the result of assembly error on the part of Formlabs.
Or a design that is prone to maladjustment.

Thus far- my experience with the printer is One good print. Two flawed prints. and 6 failures.
I’ve gone thru a tank of resin and most of a tray, and all I’ve been offered is the advice to tighten two screws that were already tighter than they recommend.

By “HELPED” do you mean the sensor errors are GONE… or you mean they are less frequent?

I agree they need to do something about the little flag like sensors. I just got a replacment printer because my resin cartridge went “missing” nearly every single layer. I really think they need a “hold button” or something. where when you insert the tank, tray or whatever it does 2 things. presses on the actual contacts of what it is. and a momentary switch to be used as a HOLD button. so so long as that button is down it holds the fact the cartridge is still there. just my thoughts

FL sent me the sane instructions. The frame CPR didn’t work for me because I still got the error after I attempted it a few times. My grounding screws were torqued down from the factory tightly as well but I backed the 2 screws out and re torqued them and have never seen the error come back. I’ve been printing for about 2weeks every day since the grounding screw adjustment and haven’t had an issue since.

well- I retorqued mine, too.

I hope I have the same result

I cannot tell too much, whether the error is gone for ever. But considering that I couldn’t even start any print because of this error and I’ve really tried soooo many times, I’ve just finished an 8h job perfectly fine.
My guess is, that the sensor is either too sensitive to errors or it’s acceptance tolerance is programmed very tight, so that there is never an over- or underfill.
Because even tightening the screws is just a way to bring the sensor in the correct alignment to the tank as it is with the thing I did, pushing the frame until it’s back in the original position.
Might be wrong, but for me it’s currently the only explanation.

I have tried it with the door open. I have tried it with the lights on and with them off.
I have had it stop at 20c and had it stop at 30 c.

I don’t understand. The printer won’t start until its working temperature is above 31C. It is the working temperature of the printer that’s important here, not the ambient temperature of the room it is in.

I’m in the same boat as most here in this thread. I couldn’t resolve the resin sensor error. Your approach might be the solution, one question though: What “grounding” screws do you mean? The common ground contacts on the power supply? Do you mind taking a picture of those ground screws? Thank you!

No no, the grounding screws are something different. See the attached PDF:
LevelSense Grounding Screws, Reseating the LevelSense Grounding Screws.pdf (543.3 KB)

Another reason why I think it’s the sensitivity or tolerance of the sensor is, because there is also this instruction to insert the tank and rotating it a bit counterclockwise or inserting the tank until the printer says “Tank inserted” even if it did fully snapped into the frame. For me these things didn’t work, but it’s kind of the same thing, trying to align the tank to the sensor.

By the way: I’ve just started another 6h print with no sensor error :slight_smile:

Thanks for clarification. Tightening/retightening those screws didn’t help either. I share your opinion that it might be an issue with the sensitivity or the threshold of the level sensor. I did a firmware update a few weeks ago (i successfully printed parts after that though) but i think the error is now much more frequently. They might have changed the sensitivity in the firmware, since there were a lot of problems with overfills (in the forums) and FL wanted to get to the safer side with higher sensor sensitivity, causing more false-positives. I had an overfill issue myself, cleaned and reassembled everything and it still worked properly after the clean-up. Now i can not get a print to start because of the resin sensor error.

they send you a white paper showing you how to find them and adjust them.

The level sensor is this rectangular plate on the Z tower just behind the tank.
The top corners have two screws holding it on…
But below the level of the carrier- where you can’t see, are two more at the bottom corners.
These they are calling Level Sensor Grounding screws… But the name conflates it with Printer leveling screws that are on the bottom of the machine.

Anyway, you have to remove the tank - slide the tank carrier over and line up two holes with two other holes to even find them screws and then you have to scare up an OFF SIZE allen wrench of 1.3mm that has a long enough bit to reach thru the two sets of holes to get at the screws.

I went to a major electronics store and out or twenty different brands of small electronics tools, only ONE of them had a 1.3mm allen bit.

They tell you to Tighten the screws HAND TIGHT only- like screwing on a pen cap.
But the damn things are WAY tighter than that.

So I backed mine off and then retightened them to hand tight.

You want to be carefull with the operation because you are practically laying the wrench on the glass window for the laser… so they ask you to cover the entire window with a lens cleaning cloth.

So last night I ran my first print since doing this and it printed perfectly without error… but then again, I have had ONE OTHER print run perfectly despite the error problem,… Plus it was a new tank and Different resin- the clear resin, so I do not yet know if this solved the problem long term or if it was a problem only associated with the durable resin.

Hopefully, it solves it.

But, again, all the tips on the support FAQs center around operator error… when this is clearly a component or assembly error on formlab’s part.

it perhaps appeared in get worse with a firmware update to prevent overfill problems… but that, again indicates that the sensor they installed is simply not ideal.

I am going to ignore the rotating the tank thing, and stop combing my resin… the resin level sensor needs to WORK, as advertised.

I’ll report back on future prints in regards to whether the screw adjustment worked,

The printer is getting the RESIN up to temperature… but all it does is heat the resin, it does not heat the entire machine.
The temperature of the room/cabinet IS a consideration, because a very cold cabinet will take a lot longer to heat the resin… but more importantly , it causes metal parts to contract. And the material the sensor is made out of, itself, might have a different response based upon temperature.
A very hot room means the resin might already be hotter than is ideal… but more to the point it causes metal parts to expand- which in the case of a cracked solder joint, or loosely fitting coupling, could cause the loss of ground to the senor resulting in signal noise, like a turntable pickup that is not properly grounded induces a hum.

The specs on the Form2 specify a very narrow range of temperatures for the environment in which the machine is running,

okay- so far I have been running prints non-stop since I loosened and re-tightened the sensor ground screws.

I had a 10 hour print run without resin sensor error- and I am 10 hours into a 20 hour print without a single resin sensor error.
This is the longest i have been able to get the printer to run without pausing.
This is more like the machine I thought I was buying.

So For those still having the issue, try the above linked screw adjustment… but be prepared to first have to loosen the screws and then re-tighten them with less torque than they already have.

I wish I had more Durable resin because I have this nagging fear that the more viscous resins may be harder for the sensor to read… and I would like to rule out that the problem only went away because I am running Clear resin.

but thus far… I am encouraged.

I have a well ventilated area around the printer, no EMI sounds but I keep getting the resin sensor error again and again. Support have sent two different tanks to replace and I have sanded and cleaned all of the sensors but I have no idea why the problem keeps persisting. Sometimes it can go a whole print through several hours and be fine, then I try a new print and the resin tank is suddenly ‘missing’. What the heck is going on??