Straight surfaces have weird lumps

Hello people,

I’m having some weird lumps showing up on straight vertical surfaces on models and I have no idea why. Any clues?

Do they only appear on one side? Like just the front side? or just the hinge side? etc?

In this case specifically, the sides of the tank are parallel to the front side, so perpendicular to the hinge side. And they appear on both the tank’s sides. My guess is that the peel is too strong due to the shallow angle and is deforming the layers, but I’m not certain.

I’ve had similar issues and I tilted the object 20-30 degrees to the side. In my case that worked.

  • Walt
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Try lowering the resolution. That looks like the resolution was 0.025mm which does that on some surfaces. More angle also helps. I don’t really understand what causes it so I don’t have much else to help.

If you are not in a conversation with support yet I would recommend sending in these pictures. They can help to determine the cause of the unwanted texture.

The resolution was 0.05. I’m currently printing another test, with a different orientation. Also cleaned the main mirror, the resin tank’s base and PDMS and replaced the resin. Will know something in the next 4 hours or so

Hi Melinda. I just did. I’m pretty sure it’s down to user error, but I have to cover all my bases

So, the print is now ready and there’s still some lumpyness showing, I’ve changed orientation but perhaps I still need to tilt the model even more. My guess is that the flat crosssection of these areas generate excessive strength during the peel process. Perhaps thickening the wall will help solve this or even further tilting. Btw, the wall thickness is 1.5mm, for a 50mm model

Just spit balling here but… If you have a bottle of another resin, try the same print and settings using it. I was having a lump issue not long ago and it turned out to be older material. I switched to a fresher bottle and it worked.

Okay, then I went back to basics. Using the older goo, it worked better when I:

  1. Shook the bottle for about 3~4 minutes.
  2. Cleaned the bottom (exterior) of the tank super clean
  3. Used the putty blade to search the bottom surface of the tank for lumps or old build junk.

A trick I have been using lately that seems to really improve my prints is, just before each print I use the putty knife to “wake up” the PDMS surface. (I’m probably nuts here, but it works) My putty knife edge is super smooth and sanded so the edges are round and not sharp. I use it like a paint brush back and forth on the PDMS surface with the tank still full of resin. I do this until the trail left behind the stroke of the blade is streak free and smooth and clear.

Carter, I don’t think you are nuts! I too use my putty knife to run along the PDMS, especially if I haven’t use the printer for a bit! I swear it helps! :slight_smile:
I am also working my way through several old bottles of resin that I suspect might be giving me issues from time to time. I shake them a lot, and always strain between each use.

Hello Carter.

I usually follow that method as well, enhanced by further combing through the resin with a small plastic comb to really filter the resin. I usually also move it around the tray with the putty knife to mix the components in the resin. I’ll try a print with another material to see it it’s the resin

I “stir” the resin in the tank every time I print even if I don’t add new resin. I make sure I go in all directions and even diagonally. I don’t use the metal blade but have a plastic one about the same size. I feel the plastic is a bit more kind to the silicone surface inside the tank. I probably do a “no no” in I scrape the blade off on the side of the tank to put what resin is on it back in the tank before wiping it off. I’ve had really good results this way and I’m on my third bottle of Grey V2 with the same resin tank. No clouding either of the bottom but then again, my builds are small and generally run around two hours average.

  • Walt

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