Settings to create a negative form
Hello friends,
I am new to this wonderful world of 3D printing. I want to create a part made of concrete, basically two cylinders with the same inner size but different circumferences. I modelled it in 3D - so far, so good.
After that, I created in Tinkercad a negative form of that part. Because of its shape I think it is necessary to split the whole thing in two symmetric parts, one looks like this:
So, my idea is to mount the two halfs together, fill them up with my special liquid concrete. Because I suppose the concrete is very heavy which destroys my 3D negative, I think it is necessary to create a very solid negative form. After 2 tries with different infills, I came to the conclusion to print just the outline of the shape and do the infill with liquid epoxy.
And now, I am looking for the right settings. I found how to do top perimeters "0" so that I can fill in the epoxy from the top. But when I select "Infill 0%", the perimeters of the upper cylinders need support material - and although I was looking and trying several hours now, I did not find a way just to print "perpendicular supports", so supports that are exactly below the necessary area.
For example: this is layer #154. Zero infill so that I can do it with epoxy after printing.
But in layer #155, the green arch is printed "right in the air", Prusa does not create any supports, so this will not work:
So: what could I do to make Prusa create appropriate supports that are right underneath the arch? Same problem with inner arches, too. All three green arches shown in the image above should be supported directly from the bottom.
Any help appreciated. Thank you!
Heiko
RE: Settings to create a negative form
In addition: it seems to me that Prusa does not realize that the green arches need to be supported. Even with automatic supports activated, Prusa just creates the "unnecessary" supports, but not where they are desperately needed...
RE: Settings to create a negative form
Have you looked for 'dont support bridges'? In print settings support material settings.
It might be might be ticked ..
Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Settings to create a negative form
And what's stopping you from creating the necessary support structures directly when creating the mold, instead of relying on PrusaSlicer? Here you have to start by saying that the primary body will be a mold in which a cavity in the shape of the concrete casting will somehow "by the way" be created, not that the mold is a derivative of the casting. And at the very end: nowhere is it written and given that the half of the mold must be made of one piece. If you divide it cleverly, you won't need any supports.Just think.And I can say that such a simple form is a matter of about an hour of modeling.
RE: Settings to create a negative form
Upload your project as a zip-compressed 3mf project file, and we can take a look. There are many ways to adjust support settings. Save the project as 3mf, zip compress (or the forum software will choke on it), then use Attach file (below the text edit field) to attach it to your post.
Formerly known on this forum as @fuchsr -- https://foxrun3d.com/
RE: Settings to create a negative form
Thank you so much for your answers.
@miroslav.h4: Last night in bed, I had the same idea that you are talking about... splitting my model like this will not work, no matter how stable the casting will be. Thank you for pointing me to the right direction!
I will start a new way of cutting it differently and will be right back... the positive form that I need made of concrete is attached for your information.
Thank you!
RE: Settings to create a negative form
Ok, I thought about it again - now I cut the model in xy pane - I hope this a better way to fill the model and get the solid object without any problems.
But now, I am back at my filling problem: I wand to fill the two forms with epoxy. Therefore, a 0% would be ideal, but 5% is also ok so that the expoxy is able to get into.
But for the inner rings, no supports are created, the rings are printed "right in the air" here with 5% infill).
What I would love to have: 0% infill, the yellow cylinder walls (yellow arrows) should be fully supported until the bottom of the model, and the infill of the inner cylinder should have no infill at all.
So: ist there a way do it like this? Or am I still on the wrong way?
Here is the new 3mf model: flare-besser
Thank you for all your help!
RE: Settings to create a negative form
Answer to my question: after a lot of reading, I found the key to what I was looking for: I added a "modificator" which allows to individually change infill levels.
So I added 2 "rings" with 15% infill (should be enough I hope, it's just a supporter for the perimeters from layer #15 and obove) and a cylincric modifier with 0% infill for the inner cylinder that will be filled by epoxy.
I hope this will work now.
Let's see how this works.. 🙂