Forming a circle


I am trying to make a circular piece but I cannot get the printer to print the item out without the circle being a series of flats rather than a clean regular circle.

I’m using Sketchup to design the piece and it looks fine but when I export the STL file into Studio the image shows the item as being a series of flats, it also prints out with a series of flats.

I am also getting a raft which should not happen as that option is off.


The problem with you ‘flats’ is that you are not exporting your STL correctly. I use creo as my cad software and if I have anything with curves I set chord height to 0 and angle control to 1. This allows the stl to make the curve. I have also had the raft issue before and I just closed the software and reimported the file.
Google how to export curves with sketchup but the concept should still be the same.


This is called faceting, and it’s the nature of an STL file, actually. The surfaces of the models that we print are made up of a mesh of triangles. A perfect circle or curve or sphere will actually be made up of these tiny flat surfaces.

What CAD program are you using? There’s probably a way to have it increase the quality of the STL export. Some programs even let you specify how many segments would make up a cirlce. Sketchup starts somewhere around 16, and you can increase the number to get a higher resolution.


I use 3D builder as a quick tool for viewing STL files. See if it’s displayed the same in there or in another STL viewer.
As for your raft, is it the same using both slic3r and cura?


Thanks all for the info.
Having now played around with the STL parameters the “faceting” is much reduced.


I can’t say that I’m a fan of 3D builder.

It makes ridiculous shapes and facets out of very simple geometries.


You are right Jimustanguitar, I can’t defend 3D builder from that criticism. It is quick for viewing files however. I use it for cutting up Lithophanes and I will say that other free programs like Blender leave big holes in a cut pieces and 123Design takes forever and most often gives up after an hour. At least 3D builder does work and fixes it’s mistakes even if it leaves a horrible mess that takes twice as long to process the next cut. It’s free and I like the way it snaps one object to the center line of another which makes it really quick to use. I suppose you could call it the “cut and shut” app for 3D printing!


It’s not stupid if it works :slight_smile: As long as you’re getting the convenience and results that you want, that’s what really matters.