Hello Community,
my name is Peter and i am running a printing business.
I am fairly new to Formlabs printer because as sla-machines we have bigger printers from Prodways hoewever i do like our Form2’s.
So presently i am running in problems with a certain customer component.
The surface needs to be as smooth as possible so i am using Formlabs black with 0.025mm layer height. But it comes out almost like an FDM print.
i am not sure yet how to upload the file so please excuse me when i fail for the first try.
Thank you in advance for any help and/or input - settings?
This looks like an artefact of the resin. Both white and black resins have a gloss surface and any slight imperfection in the orientation of the layers will result in the sort of surface you have found. It’s a bit like a broken mirror giving a disjointed image. The grey resin has a matt surface and this will look smooth because it doesn’t reflect light in the same way.
You don’t say what the final finish is intended to be, but giving the piece a coat of primer paint plus a top coat of gloss should give an acceptable surface for anything other than a mirror finish.
thank you for your response. Your explanation makes sence to me.
Well this part is for a silikon mold and later on for chocolate pouring so the surface needs to be almost perfect smooth.
Due to the food application i can not paint or coat the part - unfortunately.
May i ask you for your advice on the orientation of the part?
Would you be so kind to provide me with your "print solution?
Well, if you need it smoother without any post processing, I’d try to print it directly flat on the build platform without any supports. The surface will be extremely smooth that way.
By the way, the 3D print material is not food safe. So coating the part with a food safe epoxy is highly recommended and will smoothen things out.
So there are a few things you could try here. As billb said, the glossy resins show every imperfection, so you’re probably going to need more than one.
The first thing is that I think you may actually have two types of lines here. If you look in the well around inner rectangle, you’ll see some lines which might actually be caused by the structure of your STL file.
What’s going on here is that your STL file has two separate shells. One is the outer frame and the other is the inner block with the text on it. Where the two meet (the bottom of that well) they appear to be coplanar. PreForm struggles with coplanar surfaces like that, and the result is often an artifact that looks like “layer lines”. I think that might be what we’re seeing here because of the way they’re heavier on one side than on the other. There are two ways to deal with this. If your CAD program allows, you can “union” the two shells together. If that’s not an option, then you can push one of them so that they actually overlap a little bit instead of just barely touching. That’ll make the bottom of the well easier for PreForm to slice correctly.
But that doesn’t explain the lines around the text because your next is all in the same shell as the rectangle around it. So these are real “layer lines” and we’ll need a different trick. One I would consider is to break the first rule of orientation and actually print this parallel to the build platform. There’s actually an optimization in the way we “paint” big flat areas which are parallel to the build platform, and they come out really well. We usually recommend that you don’t put your object parallel to the build platform like this because it will mean that the “peel” forces are pretty high. But in this case, you’ve got a model which looks nice and strong, so I think I would go for it. I printed the object at the bottom of this blog post that way, and it turned out really well. Note that I would only do this for the so-called “GP resins”. Resins like Flexible, Tough, and Durable have some “give” to them and need more support.
If you do print this parallel to the build platform, you might even be able to print it without supports. It will be a little tricky to get off the build platform because you won’t have a raft with that nice beveled edge, but I might give it a try. Someone on the forum can show you the “diagonal cutter” trick for getting it off.
So those are some of the things I would try. We’ll all be interested in seeing what works for you. Good luck!
Sure, one of the best examples was in this thread.
If you create a model that has two shells which exactly touch each other, then the math involved in generating a slice through the plane where they touch gets rather squirrely. Some raster lines will manage to sneak between the two shells, while neighboring ones won’t. The artifact you get looks a little bit like layer lines, but it is usually quite a bit worse, and it is often only on the “downwind” side of the coplanar section.
As I said earlier in this thread, you want to avoid this, even though it’s only going to bite you when a layer of your print happens to hit the coplanar section. The “best” way to avoid it is to union the shells together in your CAD program. That way there won’t be any ambiguity about what’s supposed to happen in that area. If you can’t do that, then the next best trick is to push the two objects closer so that one actually sticks a tiny way into the other. PreForm will do the right thing in this case. It will laser the area inside both shells exactly the same way it will the areas inside either one of the shells.
I looked for this in this case because I often see people make this type of object by setting the text characters exactly on the plaque. But that’s not the case here. In this case, the text is in the same shell as the flat area behind it. The only place in this model which has this issue is down in that gutter around the outside.
as i promised before here are some pictures of the final result.
i am am very happy with the print and so is my customer.
There is a little tiny hole in the outer frame of the mold but that doesn’t matter at all.
Again, thank you so muc for all your efforts and inputs in my issue. You solved it and saved my life
Protip you can fill that hole in with some uncured resin. What I do to fill a hole is take a toothpick, dip it in some resin and drip it into the hole. Then either using a UV pen light, or by putting it back in the UV chamber for a short bit. Depending on how thick the wall is, repeat a couple of times. (IMO don’t try to fill the hole in one go, it will cure better if you do little bits at a time.) Then if it bulges out a bit u can slice/sand it down and viola! It’s like the hole was never there!
Another pro tip is to prevent these holes from happening.
What you see is caused by pressurized air that is trying to get out while the part is in the tank. Drill a tiny hole somewhere at the beginning of the model for venting.
