Ultimaker Community of 3D Printing Experts

# Walls vs top and bottom layers

## Recommended Posts

Posted · Walls vs top and bottom layers

When rotating a design for printing,  does it change what Cura considers the outer walls and top/bottom layers?  For example, if I take a box and rotate it on its side for printing, will the side of the box that now sits on the build plate, be considered the bottom layers by Cura?

##### Share on other sites
Posted · Walls vs top and bottom layers
4 hours ago, Rvalecruz said:

will the side of the box that now sits on the build plate, be considered the bottom layers by Cura?

Yes.

Cura does multiple steps.  One of the early steps is to "slice" which means cura takes each of the layers and represents a plane and intersects that plane with all the triangles in the STL file (an STL file is an unordered collection of triangles - there is no information in there that says which triangle goes with which).  This is done *after* the rotation that you specified so the triangles are already rotated into their new postitions.

At this point (for each slice) cura has a huge list of straight lines in 2 dimensional space (because we intersected with a plane.  Those randomly ordered lines are then linked up into loops.  The edges of those loops are considered the WALLS even if they are "holes" inside the part.  At the same time cura tries to figure out which side of these loops are inside versus outside.

The TOP/BOTTOM areas are figured out differently - obviously everything printed in the very first slice is "bottom" but there can be "bottom" portions half way up the print as well.  TOP/BOTTOM is figured out in 3 dimensions.  Walls are figured out in a single 2 dimensional slice.

## Create an account or sign in to comment

You need to be a member in order to leave a comment

## Create an account

Sign up for a new account in our community. It's easy!

Register a new account

• ### Our picks

• Why should we be the only ones asking questions? Join us and ask Jabil all your questions on September 22nd 5pm CET
• 3 replies
• Save your seat for either broadcast on September 23.
What will you learn?
· Best practices for iterative print preparation and every lesson you should learn from each print
· The right way to use per-object settings and when they are most useful
· Easy-to-use resources for anyone who wants to develop their own printer definitions, plugins, or print profiles
· How to optimize print profile settings and whether to “keep” or “discard” changes
· When is the right time to export your drawing from CAD? (Based on Ultimaker Cura’s surprising power as 3D control software)
· And a whole lot more tips and tricks!

How can I join?
This free masterclass will take place twice:
1. 11am CEST (5pm SGT, 5am EDT)
2. 5pm CEST (11am EDT, 8am PDT, 11pm SGT)
• 0 replies
• It doesn't matter if you are using 1 Ultimaker or 10, there is inspiration in everything. We're looking for ...