What is causing these stripes and tears?

[garethashenden]

I have a new Photon Mono 4K. I've been trying it out with some 2mm scale wagons and I've got some weird problems. The beginning of the print has some ripples and tears in it, then it sorts itself out and prints beautifully. I have the whole body angled upwards. Once it gets above the end of the wagon it looks great. I tried it at 20° and 30° with the same results. All the other settings are the same, 0.035mm layer height, 2 second exposure, and Anycubic Craftsman DLP resin. While I have been printing for a while I still don't really know how to fix things like this. My two ideas are either a 0.050mm layer height or increasing the exposure a bit, but I'm not sure how much a bit should be.





In the most recent batch I also printed a cattle wagon. It needs more supports in places, but doesn't have the ripples per say, but there are some gaps. There should be gaps, but they should be straight.

[John]

Some of it is not enough supports - and print angle ..

[garethashenden]

Ok, I can add more supports, but what do you think the angle should be?

[Chris333]

The only thing I print at an angle are round boilers.

Also if you put the support with just a hair space between them and the edge you won't have as much body work to do. Your supports are right on the edge and up the side.

[garethashenden]

Yeah, I'm coming around to the angle being the main problem. I added a sacrificial skirt on the sides and printed it at 5°. The skirt worked, but the sides are even uglier. I've got it printing flat now.

[Chris333]

Also you might need to take the roof off the one car. It will print better and you can skin it with styrene easy.

[bbussey]

You need a lot more supports. Also, I would calculate the arctan for your pixel size and slice layer thickness, and try that.

Also the model position above the build plate seems low. I set the model at least 6mm above the plate.

[garethashenden]

Also you might need to take the roof off the one car. It will print better and you can skin it with styrene easy.

Its not my model, I got the stl from the designer. The open one is my model though.

You need a lot more supports. Also, I would calculate the arctan for your pixel size and slice layer thickness, and try that.

Also the model position above the build plate seems low. I set the model at least 6mm above the plate.

The version currently printing is 5mm  above the build plate. The previous ones were only 2. I don't know why I thought that was high enough. I probably didn't think.

[garethashenden]

Now I don't know what to think. This was printed level starting 5mm above the build plate. The sacrificial skirt worked great, but the lines are even worse.

[Chris333]

It almost looks like there is something wrong with the lead screw, that or the FEP is very loose. I don't know.

I'm using 0.05mm layers for everything since I started printing. And right now at 4 seconds, but I'm using a different machine.

[C855B]

It almost looks like there is something wrong with the lead screw, that or the FEP is very loose. I don't know.

I was thinking FEP tension, as well.

[garethashenden]

The FEP feels tight, but I gave all the screws a quarter turn and now its definitely tight. Trying again. Haven't made any other changes.

[Erock482]

Looks like suction issues, see how once enough of the car printed in the sloped orientation the artifacts ended once the layer image was three sided instead of 4?

Is the bottom of the car facing down? with the walls being printed last?

Try either A flipping the car upside down allowing air to enter between the supports, or add some vent holes in the floor of the car so air can escape there.

[bbussey]

It seems to be lateral movement.   Tightening all the screws is the first step, including the build plate and the screws holding the resin vat.

I had similar problems and they were due to the magnetic build plate that I had installed.  The removable plate had started shifting on the magnet during builds and was causing the visible layering, which got progressively worse as the magnet weakened over time.  The magnet also was interfering with the controller board, causing the machine to lose the Z = 0 calibration regularly among other things.  I went back to the original rigid build plate and all those problems went away for me.

Based on your last Chitubox screen shot, your raft still appears thin.  I use a 1mm raft with a 1.5mm perimeter height and 60% slope.

[peteski]

Try either A flipping the car upside down allowing air to enter between the supports, or add some vent holes in the floor of the car so air can escape there.

I didn't realize that air could get trapped inside the printed part. I thought it was immersed in resin.