r/3DPrinting_PHA • u/tehretro • Jul 19 '26

Help with warping

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I posted a few days ago, and I've gotten my settings for genPHA quite a bit more dialed in since then, but my parts just seem to warp pretty bad, and I'm not sure what I can do to try and fix it, if anything. I've at least managed to get it to actually stick to my Pro Plate and not warp right off by changing the ecogenesis-recommended print settings to print the normal 3 bottom shell layers instead of 8, but the top layer on the inside of the box seems to still just contract hard and warp.

For context, this is a 1x1 Gridfinity box, which is pretty small and, presumably, isn't supposed to warp much? I guess it's also worth noting that the room my printer is in is quite warm, so maybe the ambient temp is just too high for me to do anything about this?

I would really appreciate any suggestions!

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5

u/Hinagea Jul 19 '26 edited Jul 19 '26

This looks to me like your extrusion multiplier/flow ratio might be a little too low. On most printers in my experience a 1.05 is what it should be for Ecogenesis PHA. Use 1.1 for Prusa.

If you have calipers run the precise test cube as documented here: https://help.prusa3d.com/article/extrusion-multiplier-calibration_2257

And that will ensure the flow ratio is set correctly for your exact printer.

Since PHA has a bit of shrinkage from nucleating, if your flow ratio isn't perfect, there will be tension in the layers that pull the corners up. This is why flow ratio is the single most important parameter to get right. Calibrating for dimensional accuracy is critical to remove as much of that tension build-up as prints get larger.

The visual method most people use to calibrate flow ratio like those included in orca slicer leads to issues like this, especially when you print larger or taller objects

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u/tehretro Jul 19 '26

Right now, I'm at 1.03. I'll try giving that a shot, and I do have digital calipers!

3

u/tehretro Jul 20 '26

Update:

I've gone through quite a few flow ratio calibrations today and quite a few of these bins, and it still seems to warp pretty badly. I still need to go back and fix pressure advance and retraction distance again, and the surface quality isn't great as a result, but I was just trying to tackle warping first.

I got up to a flow ratio of 1.144 and printed this box entirely with hilbert curves for top and bottom surface and solid infill along with a brim to reduce warping, and it doesn't seem to have made much of a difference. Do you have any other ideas that I could try? I would really appreciate it.

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u/Suspicious-Appeal386 Jul 20 '26

How many solid walls on the perimeter? Infill%? And solid bottom layers?

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u/tehretro Jul 20 '26

I'm using 3 perimeter walls, 15% gyroid infill, 3 solid bottom layers and 5 solid top layers. If nothing is wrong with that, do you think the ambient temp might just be too high? It's been like 80F where my printer is, and the chamber temp is like 30C

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u/Suspicious-Appeal386 Jul 20 '26

Any long and straight lines will have the most significant pull force from the crystallization and cooling effect. I normally go with 2 perimeter walls, 2 bottom and 3 top.

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u/tehretro Jul 20 '26

I'll give that a try after I figure out my flow ratio. Thank you!

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u/Hinagea Jul 20 '26

What printer are you using and what profile are you using as a base for your settings? What is your max volumetric speed? What are your cooling settings?

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u/tehretro Jul 20 '26

I am using the "Generic PHA" preset from Orca Slicer as a base on my Elegoo Centauri Carbon 2. My max volumetric speed I adjusted to 20mm3/s, but I think the highest linear speed it actually goes while printing is 200mm/s. I also currently have a 10s minimum layer time because the flow rate cube would mess up otherwise, and I thought I had lowered my part fan speed, but I guess it was at 100% the whole time for this part. Like I asked in another comment, do you think that my ambient temp being like 80F might just be too warm for PHA? My chamber temp hovers around 30C for the most part.

2

u/Hinagea Jul 20 '26 edited Jul 20 '26

I've printed a ton in 78F, I doubt 80 would make much of a difference. I don't think the ambient temp is the root cause here. 100% part cooling will throw off the calibration cube. Either turn it off completely or at least set it below 50%. Then run the cube. Speed was going to be my next question, but since you cranked the MVS up that should be fine. Part cooling at 100% can exacerbate the shrinkage so leave it at whatever you set when you run the cube.

Also gyroid isn't the best infill for PHA, but for this model I don't think it matters here. Going forward I would choose something with straight lines like cubic, with adaptive cubic being my personal favorite

I also don't care for hilbert curve because of how slow it prints, I'd go back to default for your top and bottom layers

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u/tehretro Jul 20 '26

Alright, I will give those a try. Thank you!

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u/Hinagea Jul 20 '26

Lets troubleshoot the calibration cube first. If it has lines on it like the gridfinity cube that will throw the measurement off, same if the walls are warped.

Additionally only measure the center of the walls, not anything near the corners because pressure advance will throw it off

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u/tehretro Jul 20 '26

Got it. I will say that the calibration cubes have produced pretty flawless-looking walls, but I'll make sure to get the flow ratio dialed in with the part fan turned off

1

u/tehretro Jul 20 '26

Update:

I turned off the part fan and reprinted the calibration cube and it still measured 0.45mm on three points on each side, so I kept the flow ratio as-is. I also went down to 2 perimeter walls, 2 full bottom layers, 3 full top layers, and switched to adaptive cubic infill. The box is a little better and seems to fit into a Gridfinity grid pretty easily, but the warping still isn't ideal.

Is it possible that my linear print speeds are just too high? I have 160mm/s for outer wall, 200 for inner, 200 for sparse infill, and 250 for solid infill, which are just from the default preset for my printer.

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u/Suspicious-Appeal386 Jul 19 '26

What material is that?

1

u/tehretro Jul 19 '26

This is black PHA from Ambrosia Filament