Prints are splitting around supports, any ideas why?

I’ve started having prints split around where supports attach to the print.
This is happening with clear resin V2 in a bath that’s no longer fresh (but no clouding and less than 1L of resin used in it). I also print in black and flexible and don’t see these issues.

I’m curious as to why this is happening. My guess is that, as with many other problems, it will go away if I swap out the tank and/or get new resin, but I kind of want to know what’s going on.

It looks like the support creates its own standalone structure that takes many layers to finally merge with the other structures.

My best guess is that – because we’re in a warehouse that experiences multiple temperature swings on the order of 10+F throughout the day – I’m seeing contractions in the printed material pulling the two sides of the print away from each other. I know there are internal heating elements but I can’t think of a better explanation.

Has anyone had similar issues? Any explanations?

Thanks

If this is a Form 2, I would think that the printer’s heater would be able to handle temperature swings like that, so it’s probably something else. But if you really do think it’s that, here’s one thing you could try. In the Advanced section of the Supports flyout, there’s a field called “Height Above Base”. If you turned that up a bit, then the supports would have a little more “flex”. That might reduce the stresses if it really is a temperature swing problem.

Or maybe you could knit a “printer cozy”.

Here are a few tips for thin walled parts

Always try to place the thicker sections next to the build platform and support them more heavily. If the printer starts with a thin section and goes to a thick section it puts more stress into the part. Starting with the thick end and ending with the thin end will put a lighter peal force at the end and less stress in the part. (for your print the highest point in your print is unsupported adding stress.)

If you have parts that fail try editing the supports manually and adding additional supports. You can use small point sizes to make removal easier.

Another tip for part quality and cleanup is to move support points off of the corners (just off the corner not far). This will be easier to get a nice clean edge on the print. The lowest point still needs to be on the corner to avoid unsupported areas but the rest can be on a flat surface.

It looks like you need more supports near the starting corner to keep the print stable while it prints, if you don’t have enough structure then the print can flex a bit while printing and become misaligned.

@FredB
“If the printer starts with a thin section and goes to a thick section it puts more stress into the part.”

I hadn’t thought about that, that’s good to keep in mind.

I’ll add more supports around failures on subsequent prints, it’s a little annoying because I don’t know where the failure will be until after I’ve printed it (obviously).

@Zachary_Brackin

This is likely what’s happening, I’ll just start adding more supports along the corner.
What’s weird/annoying about this type of failure is that it’s not restricted to corners or edges so it’s hard to predict what might be susceptible.

I’m throwing in another picture to illustrate what I mean (post support removal, though).
Each of the “teeth” is its own support contact point. They eventually merge back together but not before serious warping occurs. There is a large “tooth” on the edge but the other ones start independently of the edge one. (sorry, no Preform screenshot, this was printed a while ago)

@mgarrity

This is a good point, I always reduce the Height Above Base to bring down the print time but I’ll leave it a bit higher in light of these issues. I’m not sure why this problem would start popping up now since this is how I’ve been printing since I got the Form2, but old resin/old tank might be enough to explain the incidence of the issue.

Angle looked too low with the thicker part on the wrong pitch. Heaviest part low, steeper angle and a few more support if you need. Usually PF does a good job with supports.

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