Printer Making Knocking Sound

My Form 2
is making a knocking sound when the resin tray is sliding to the right. The
sound happens as it’s getting to the far right. This started to happen after
using only 1/3 of the first 1l resin. I removed the tray and checked for some
parts that could offer some resistance to the movement of the tray. None was
found. I could replicate the sound if I manually shifted the tray to the far
right. Today I started a new print (11hours) and will see if the knocking
affects the print quality.

suggestions how to solve this?

Thanks in

1 Like

unleaded resin? :slight_smile:

edit: Doh! it was leaded gas that stopped knocking… NM.


My printer just started doing this. I can see the resin tray move a little to the right and then snap back coincident with the knocking sound. It does it a few times before the tray finally moves as expected.

I’m printing an object that requires a large base, that almost completely covers the build platform. The knocking occurred on every layer for the first 20 layers. It stopped doing it on the 21st layer.

My guess is that the printer is having a little trouble breaking the print away from the bottom of the resin tank, due to the large amount of surface area of the base. Whether this behavior is by design or an indication of something wearing out remains to be seen…

I have
printed 3 prints after I experienced this sound. In my case the sound persisted
through all layers. The last two prints the sound slowly (it was less and less
loud) disappeared. I hope I will stay like this.

Well, I opened a ticket and asked some questions. Will update here if I get any useful information.

From watching my printer while it was doing this, I’m guessing there’s a detent/spring type torque limiting clutch on the resin tray drive mechanism. I could hear the stepper running, and the tray moved right only very slowly and a tiny distance before it suddenly jumped back to the left coincident with the knock. The knock sound would be the clutch slipping to the next detent.

I’m guessing the build platform is under tension as part of the peel, because after 3 or 4 knocks, on the next cycle when the tray broke free and finally moved to the right, the platform would also pop up slightly.

After layer 20, the noise stopped. And the entire print (a 1500 layer job) completed fine and the print looks great. So I’m not too worried about this. It’s annoying but I suspect within the design parameters of the mechanism.

Hi Randy,

I had this problem also with a print with many parts and only a little empty room between the basements of the parts.

it`s a problem based on your big basment of your part.
The first 20 layers are the basement, in layer 21 the building of the supports starts and
these are only small points on the silicone.

The noise comes from the peeling when the silicone snaps back to the bottom of the tank.

My parts are also okay.
A absolutly new tank may help to solve this problem or a basement with some empty rooms.
Is this basement from the newest preform?


Hi, Kalle.

I know the problem is being caused by the large base of my print. But the noise is not from the peeling, there’s no snapping of the bottom of the tank. The peel doesn’t work that way. The problem is occurring because the print is stuck. The printer tries to move the resin tank to the right but it can’t because the print is too-well adhered to the bottom of the resin tank and the build platform. It moves a little as strain builds up in the mechanics, though I can’t tell if it’s the build platform that’s wracking or the PDMS is getting stretched out, probably it’s a little of both. The noise occurs because the stepper motor drive that’s trying to move the tank “slips”. When it does, the strain that’s been built up is released and the resin tank snaps back to where it was prior to the peel starting. When it does this, it makes a loud “bang”. The printer continues to try to move the resin tank so the cycle repeats.

It’s clear the printer knows the resin tank isn’t moving because the cycle repeats for much longer than it takes to move the resin tank normally. I’d assume there’s a limit to how long it’ll keep trying, and that at some point if the peel can’t complete the printer will throw an error code and give up on the print. But in my case, after maybe an average of 4 cycles (maybe 15-20 seconds of trying) the print finally breaks free and then the resin tank moves smoothly and the build platform rises up normally.

I did get a response from FL that based on my description this is not something they consider normal, and asking if I can get a video of it doing it, which I will try to do sometime this week.



yeah, that sounds more like it. sounds like (seriously, no puns intended) it’s pushing the envelope on what the machine can do. understanding what the fix is will be interesting. keep us all posted. hopefully it’s not simply ‘don’t print to the full printer’s build size’.

Like the old joke;
Man: Doctor! Doctor! I broke my leg in two places!
Doctor: Hmm, better stay out of those places!

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