AnyCubic Photon: either skipping layers or layers keep shrinking... (Page 1 of 2)

I'll try and print it this evening.

-Kevin

Huhi,

I loaded the .stl file and sliced it in Photon Slicer and ChiTuBox.  There doesn't seem to be any anomalies with the file, and it printed fine on my printer.

You mentioned that other files do the same thing...I think the problem is with your printer.  One thing comes to mind regarding the possible cause: check to see that the FEP film is tight across the bottom of the resin vat.  If you tap it with your finger, it should be as tight as a snare drum.  You can tighten it with the screws along the bottom perimeter.  If the screws are already tightened all the way and there is still slack...or if the film is stretched or distorted...replace the film.

A friend's printer started doing this once.  Tightening the film solved the problem.

Let us know what you find.

-Kevin

Could also be hazy film reducing the light and not giving a full cure time in that srea.

It should be very near optically clear like a clean window. If it is not it will reduce the light passing through which will affect the curing time. If the curing time is too low then the section will not cure enough and can be washed away during the alcohol rinse. I have a Wanhao D7 which uses the same technology so I can see this on mine when the film gets hazy/cloudy. I either have to replace the film or raise the curing time.

That looks hazy to me.  Like Carl said, it should be as clear as a window.  I have not yet had any problem with resin particles, and alcohol should readily evaporate without leaving residue (use alcohol with the least water content).  If it were me, I'd replace the film.

When cleaning the film, I use the alcohol-based glass cleaner, and just daub the excess off with a paper towel or soft cloth.  I then wipe it clean with a microfiber cloth.  Don't rub it with anything else, as even a paper towel seems to scuff it.

I've been printing like crazy since I got my Photon, and am still on my original film, so it appears they can last a while with care.

-Kevin

Hi guys. The explanation why the film may be scuffed and how bad exposure can cause my artifact made sense so I replaced my film!

The issue didn't go away. There seems to be a new issue now, or one I hadn't noticed due to the other issue. The prints come out as if the print bed is angled, lower towards the door and higher towards the other side. I am 100% confident the bed is homed and leveled perfectly. I payed good attention to how the pritner is printing and I found an issue: the bed moves lower than it should and bends slightly, and bends back as it goes up to move down again for the next layer. I have no idea why this happens. I have reset the Z=0 height several times now and the issue persists.

Note that I had replaced the motor of the printer but made sure to get the one with the same lead screw with the same pitch and lead (2mm) from Iverntech. Two of the pins had to be swapped for the motor to rotate the correct angle but other than that it seems to work fine. Not sure what the issue is.

I have updated the firmware with the latest official one as well with no difference.

yes

I can bend it (tilt) a degree or two, not move (shift) up or down. After releasing it returns to its original angle.
I'm talking about the whole gantry that slides on two rods and one lead screw the build plate is attached to, not the build plate alone. That part is actually very rigid by itself.

That's not good! 

Check to see that the eccentric nut is tightened correctly:

https://www.youtube.com/watch?v=f7gYTpBT3uk

-Keivn

The lever on your Z stop switch could have been bent over time so it allows the plate to move further down. I would redo the leveling and zeroing process.

Here is a forum where people are losing Z on your very machine..

https://www.thingiverse.com/groups/anyc … opic:32995

One guy did this which sounds very simple..

"I had this same issue... Its a bit unorthodox but I selected home, manually turned the z thread till it was nipping paper... Set z=0 and then pressed home again..."

I would read through all of those and see if any of them could apply to you.

And you are sure your sensor is not loose, has moved, or is dirty? The blade could also be loose, moved or bent.

The D7 uses a blade and sensor as well. Leveling is achieved by loosening the 4 screws that bolt the plate to the Z stage. This allows the plate to slide up or down 15mm with no regard to the Z stage.

You then lower the stage using the motor controls to the point where the sensor makes it stop. You then press the plate down on the film making sure it is down on all 4 corners.  While holding snugly against the film you tighten the 4 screws and your build platform is leveled and zeroed.

I can with 100% certainty claim the bed is leveled correctly. I can also 100% certainty say the blade is not bent and I also swapped the sensor just in case and there was no difference. I am also changing the FEP film for the 3rd time now, it is again extremely tight not hazy and there is no difference to my issues.
This is becoming a nightmare of an experience.

I fixed the "flex" but it fixed none of my issues. The flex was due to the sliding block with the 3 bearings on it getting angled when the screw holding the middle eccentric one becomes loose and you re-tighten it at a slight angle. Apparently that can happen. Took me disassembling and testing everything else to find the bugger. Now there is no flex (play) at all.

First print came up without nthe new issue I mentioned in post #12 that "the prints come out as if the print bed is angled" but it did have the issue with the upper layers as in the photo in the OP.
It did appear to me that the build plate is moving lower than it should again for the first layer. I'm worried perhaps the first layer(s) is too close to the FEP film this way and may cause the first layer to adhere to both the build palte and to the FEP film as well, among other issues such as mechanical stress on the mechanical components, very subtle bending and danger of cracking the LCD display.
This is the first issue.

It is very subtle but if you watch the video here, at 0:29 you can notice that especially the blue pieces of the build plate which connect to the aluminum slider block with the 3 bearings gets visibly bent a little from moving too low: https://www.youtube.com/watch?v=DN7SU_e … e=youtu.be

I also don't remember how it was before, but if my memory doesn't fail me the build plate shouldn't keep moving so much after the beep at 0:28. It almost feels like the motor is being instructed to do some extra steps which it shouldn't. Am I wrong?

Second issue. When I tried printing something bigger, the next print the other issue I had before with the built plate getting bent and the print coming out accordingly came back. So the flex was never the root issue for anything...

Here is the build plate during printing the second print: https://i.imgur.com/LAzWX8z.jpg

Here it is out of the printer with the printer part on it: https://i.imgur.com/DBsjBvn.jpg
As you can clearly see the bent build plate is what caused the print to be bent. Their angles are perfectly parallel to each other.

Here you see the build plate moving up then down for a new layer: https://youtu.be/0QFUF8WztSM
You can hear a clicking sound like when a stepper motor is turned on, although I don't know where the sound is coming from. Not sure if that is normal. At this point the build plate wasn't bent yet. Video starts at 0:35.

Here is the bent build plate moving up and down for a new layer. Not sure when it got bent but was after the first layers: https://youtu.be/ndEKoOee0t8

My only guess is because the build plate moves lower than it should, the print stick to both the build plate and FEP film. Initially the FEP film doesn't let go and flexes a little but eventualy does, but first pulls the build plate from the adjusted angle. This is the only logical explanation I can think of.

Any ideas? I am getting quite desparate here.